Biomechanics of Hand and Wrist Deformities in Rheumatoid Arthritis: Difference between revisions

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== Overview ==
== Overview ==


The structure of the hand provides a great deal of insight into its function.  Its multi-joint structure allows the hand to convey forces while simultaneously allowing for intricate movements at the fingers.  The carpal tunnel in the wrist allows a large range of motion to finely position the hand in space, without crushing the tendons that are transmitting forces from the large forearm muscles to the hand.  As these structures are damaged by rheumatoid arthritis, their capacity to perform their function decreases, severely limiting a person’s ability to adequately complete activities of daily living.
The structure of the [https://physio-pedia.com/Wrist_and_Hand?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal hand] provides a great deal of insight into its [https://physio-pedia.com/Hand_Function?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal function].  Its multi-[[Joint Classification|joint]] structure allows the hand to convey forces while simultaneously allowing for intricate movements at the fingers.  The carpal tunnel in the wrist allows a large range of motion to finely position the hand in space, without crushing the [https://physio-pedia.com/Tendon_Biomechanics?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal#stq=Tendon&stp=1 tendons] that are transmitting forces from the large forearm muscles to the hand.  As these structures are damaged by [https://physio-pedia.com/Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal rheumatoid arthritis], their capacity to perform their function decreases, severely limiting a person’s ability to adequately complete activities of daily living.


Rheumatoid Arthritis is a systemic, inflammatory disease that can severely compromise hand and wrist function.  It is caused by the inflammation of the synovium, which not only lines the many synovial joints in the hand, leading to stiffness and deformity, but also surrounds the tendons that transmit force from the forearm to the fingers.  This can cause tendon rupture and inflammation, leading to further weakness and deformity in the hand.
[https://physio-pedia.com/Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal Rheumatoid Arthritis] is a systemic, inflammatory disease that can severely compromise hand and wrist function.  It is caused by the inflammation of the synovium, which not only lines the many [https://physio-pedia.com/Joint_Classification?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal synovial joints] in the hand, leading to stiffness and deformity, but also surrounds the [https://physio-pedia.com/Tendon_Biomechanics?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal tendons] that transmit force from the forearm to the fingers.  This can cause tendon rupture and inflammation, leading to further weakness and deformity in the hand.


This article examines the biomechanics of the hand in patients with rheumatoid arthritis.  It explores the pathogenesis of a variety of hand deformities caused by rheumatoid arthritis, before briefly outlining how this changes hand function.
This article examines the biomechanics of the [https://physio-pedia.com/Hand_Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal hand in patients with rheumatoid arthritis].  It explores the pathogenesis of a variety of hand deformities caused by rheumatoid arthritis, before briefly outlining how this changes hand function.


== Radial Deviation and Ulnar Drift ==
== Radial Deviation and Ulnar Drift ==
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Radial deviation of the wrist and ulnar drift at the carpometacarpal joint tend to happen simultaneously<ref>Pahle JA, Raunio P. The influence of wrist position on finger deviation in the rheumatoid hand. A clinical and radiological study. ''J Bone Joint Surg Br''. 1969;51(4):664-676.</ref>.  The more that the wrist is deviated radially, the more the fingers deviate in the ulnar direction<ref>Dibenedetto MR, Lubbers LM, Coleman CR. Relationship between radial inclination angle and ulnar deviation of the fingers. ''The Journal of Hand Surgery''. 1991;16(1):36-39. doi:10.1016/s0363-5023(10)80009-7</ref>.  This is thought to be due to the biomechanics of the hand as an intercalated segment.  The muscles pull the distal bones proximally, causing a collapse into a zig-zag deformity<ref name=":0">Read GO, Solomon L, Biddulph S. Relationship between finger and wrist deformities in rheumatoid arthritis. Annals of the Rheumatic Diseases. 1983;42(6):619-625. doi:10.1136/ard.42.6.619</ref>.  Typically this deviation gets more extreme as the disease worsens<ref name=":0" />.  Other prominent theories of the mechanism of ulnar drift include collateral ligament laxity allowing the drift, increased intra-articular pressure causing deformity, and muscle imbalance<ref name=":1">Morco S, Bowden A. Ulnar drift in rheumatoid arthritis: a review of biomechanical etiology. ''Journal of Biomechanics''. 2015;48(4):725-728. doi:10.1016/j.jbiomech.2014.12.052 Morco S, Bowden A. Ulnar drift in rheumatoid arthritis: a review of biomechanical etiology. ''Journal of Biomechanics''. 2015;48(4):725-728. doi:10.1016/j.jbiomech.2014.12.052</ref>.  Many activities of daily living also pull the fingers in the ulnar direction, such as holding a cup of coffee<ref>Bielefeld T, Neumann DA. The Unstable Metacarpophalangeal Joint in Rheumatoid Arthritis: Anatomy, Pathomechanics, and Physical Rehabilitation Considerations. ''Journal of Orthopaedic and Sports Physical Therapy''. 2005;35(8):477-549. doi:10.2519/jospt.2005.35.8.502</ref>.  These activities may increase ulnar drift, especially if rheumatoid arthritis is already causing joint laxity<ref name=":1" />.
Radial deviation of the wrist and ulnar drift at the carpometacarpal joint tend to happen simultaneously<ref>Pahle JA, Raunio P. The influence of wrist position on finger deviation in the rheumatoid hand. A clinical and radiological study. ''J Bone Joint Surg Br''. 1969;51(4):664-676.</ref>.  The more that the wrist is deviated radially, the more the fingers deviate in the ulnar direction<ref>Dibenedetto MR, Lubbers LM, Coleman CR. Relationship between radial inclination angle and ulnar deviation of the fingers. ''The Journal of Hand Surgery''. 1991;16(1):36-39. doi:10.1016/s0363-5023(10)80009-7</ref>.  This is thought to be due to the biomechanics of the hand as an intercalated segment.  The muscles pull the distal bones proximally, causing a collapse into a zig-zag deformity<ref name=":0">Read GO, Solomon L, Biddulph S. Relationship between finger and wrist deformities in rheumatoid arthritis. Annals of the Rheumatic Diseases. 1983;42(6):619-625. doi:10.1136/ard.42.6.619</ref>.  Typically this deviation gets more extreme as the disease worsens<ref name=":0" />.  Other prominent theories of the mechanism of ulnar drift include collateral ligament laxity allowing the drift, increased intra-articular pressure causing deformity, and muscle imbalance<ref name=":1">Morco S, Bowden A. Ulnar drift in rheumatoid arthritis: a review of biomechanical etiology. ''Journal of Biomechanics''. 2015;48(4):725-728. doi:10.1016/j.jbiomech.2014.12.052 Morco S, Bowden A. Ulnar drift in rheumatoid arthritis: a review of biomechanical etiology. ''Journal of Biomechanics''. 2015;48(4):725-728. doi:10.1016/j.jbiomech.2014.12.052</ref>.  Many activities of daily living also pull the fingers in the ulnar direction, such as holding a cup of coffee<ref>Bielefeld T, Neumann DA. The Unstable Metacarpophalangeal Joint in Rheumatoid Arthritis: Anatomy, Pathomechanics, and Physical Rehabilitation Considerations. ''Journal of Orthopaedic and Sports Physical Therapy''. 2005;35(8):477-549. doi:10.2519/jospt.2005.35.8.502</ref>.  These activities may increase ulnar drift, especially if rheumatoid arthritis is already causing joint laxity<ref name=":1" />.


The main casualty of this deformity is the loss of a range of motion at the wrist<ref name=":1" />.  Although patients can still carry out activities of daily living, they may have to compensate for the lack of wrist motion in other ways<ref name=":1" />.  
The main casualty of this deformity is the loss of a range of motion at the wrist<ref name=":1" />.  Although patients can still carry out [https://physio-pedia.com/ADLs?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal activities of daily living], they may have to compensate for the lack of wrist motion in other ways<ref name=":1" />.  


== Z Deformity of the Thumb ==
== Z Deformity of the Thumb ==


Synovitis of the joint capsule at the metacarpophalangeal (MCP) joint of the thumb causes weakening of the capsule and its ligament<ref name=":2">Dyer GSM, Simmons BP. Rheumatoid Thumb. ''Hand Clinics''. 2011;27(1):73-77. doi:10.1016/j.hcl.2010.10.001</ref>.  The resulting stretching of Extensor Pollicis Brevis (EPB) allows the Extensor Pollicis Longus (EPL) tendon to sublax<ref name=":3">Okita S, Nishida K, Ohtsuka A, Ozaki T. A high incidence of extensor pollicis brevis insertion into the distal phalanx in rheumatoid arthritis patients who required the surgical reconstruction for thumb boutonnière deformity. ''Mod Rheumatol''. 2019;29(6):954-958. doi:10.1080/14397595.2018.1532484</ref>.  It has also been suggested that the insertion point of EPB may contribute to this disorder<ref name=":3" />.  The new volar placement of the tendon forces the MCP joint into flexion, secondarily causing the interphalangeal (IP) joint to hyperextend<ref name=":2" />.
Synovitis of the joint capsule at the metacarpophalangeal (MCP) joint of the thumb causes weakening of the capsule and its ligament<ref name=":2">Dyer GSM, Simmons BP. Rheumatoid Thumb. ''Hand Clinics''. 2011;27(1):73-77. doi:10.1016/j.hcl.2010.10.001</ref>.  The resulting stretching of [https://physio-pedia.com/Extensor_Pollicis_Brevis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal Extensor Pollicis Brevis (EPB)] allows the [https://physio-pedia.com/Extensor_Pollicis_Longus?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal Extensor Pollicis Longus (EPL)] tendon to sublax<ref name=":3">Okita S, Nishida K, Ohtsuka A, Ozaki T. A high incidence of extensor pollicis brevis insertion into the distal phalanx in rheumatoid arthritis patients who required the surgical reconstruction for thumb boutonnière deformity. ''Mod Rheumatol''. 2019;29(6):954-958. doi:10.1080/14397595.2018.1532484</ref>.  It has also been suggested that the insertion point of EPB may contribute to this disorder<ref name=":3" />.  The new volar placement of the tendon forces the MCP joint into flexion, secondarily causing the interphalangeal (IP) joint to hyperextend<ref name=":2" />.


Z deformity of the thumb prevents pinching because the force of the tendons causes the thumb to collapse into MCP flexion and IP hyperextension<ref name=":2" />.  Thumb function is important for opposition, which is essential for pinches and grips<ref>Duncan SF, Saracevic CE, Kakinoki R. Biomechanics of the Hand. ''Hand Clinics''. 2013;29(4):483-492. doi:10.1016/j.hcl.2013.08.003</ref><ref>Imaeda T, An KN, Cooney WP 3rd. Functional anatomy and biomechanics of the thumb. ''Hand Clin''. 1992;8(1):9-15.</ref>.  This deformity, therefore, can severely interrupt activities of daily living requiring opposition.
Z deformity of the thumb prevents pinching because the force of the tendons causes the thumb to collapse into MCP flexion and IP hyperextension<ref name=":2" />.  Thumb function is important for opposition, which is essential for [https://physio-pedia.com/Sporting_Hand_and_Wrist_-_Why_Power_and_Pinch_Grips_Matter?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal pinches and grips]<ref>Duncan SF, Saracevic CE, Kakinoki R. Biomechanics of the Hand. ''Hand Clinics''. 2013;29(4):483-492. doi:10.1016/j.hcl.2013.08.003</ref><ref>Imaeda T, An KN, Cooney WP 3rd. Functional anatomy and biomechanics of the thumb. ''Hand Clin''. 1992;8(1):9-15.</ref>.  This deformity, therefore, can severely interrupt [https://physio-pedia.com/ADLs?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal activities of daily living] requiring opposition.


== Swan Neck Deformity ==
== Swan Neck Deformity ==


Swan neck deformity can either be caused by flexion at the Distal Interphalangeal (DIP) joint, or by hyperextension at the Proximal Interphalangeal (PIP) joint<ref name=":4">Nalebuff EA. The Rheumatoid Swan-Neck Deformity. ''Hand Clinics''. 1989;5(2):203-214.</ref>.  In the former, arthritic weakening of the extensor tendon at the DIP causes either stretching or rupture, and the tendon is unable to extend the distal segment<ref name=":4" />.  In the former, rheumatoid arthritis causes inflammation at the PIP joint.  This leads to laxity and weakness of the ligaments, joint capsule and structures designed to provide stability to the joints, allowing the PIP to be hyperextended<ref name=":5">Fox PM, Chang J. Treating the Proximal Interphalangeal Joint in Swan Neck and Boutonniere Deformities. ''Hand Clin''. 2018;34(2):167-176. doi:10.1016/j.hcl.2017.12.006</ref><ref name=":6">Dreyfus JN, Schnitzer TJ. Pathogenesis and differential diagnosis of the swan-neck deformity. ''Semin Arthritis Rheum''. 1983;13(2):200-211. doi:10.1016/0049-0172(83)90007-0</ref>.  An alternate cause of hyperextension is that the flexor tendon becomes ruptured<ref name=":4" />.  As the PIP joint becomes hyperextended, the extensor tendon becomes shortened and is less able to extend other joints.  The resulting tendon laxity leads to an inability to extend the DIP joint<ref name=":5" /><ref>Ridley WE, Xiang H, Han J, Ridley LJ. Swan neck deformity. ''J Med Imaging Radiat Oncol''. 2018;62 Suppl 1:159-160. doi:10.1111/1754-9485.31_12786</ref>.  The hyperextension of the PIP also stretches the flexors on the opposite side of the finger, causing them to pull more strongly on the distal segment.  This also leads to DIP flexion<ref name=":6" />.
[https://physio-pedia.com/Swan-Neck_Deformity?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal Swan neck deformity] can either be caused by flexion at the [https://physio-pedia.com/Interphalangeal_Joints_of_the_Hand?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal Distal Interphalangeal (DIP)] joint, or by hyperextension at the [https://physio-pedia.com/Interphalangeal_Joints_of_the_Hand?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal Proximal Interphalangeal (PIP)] joint<ref name=":4">Nalebuff EA. The Rheumatoid Swan-Neck Deformity. ''Hand Clinics''. 1989;5(2):203-214.</ref>.  In the former, arthritic weakening of the extensor tendon at the DIP causes either stretching or rupture, and the tendon is unable to extend the distal segment<ref name=":4" />.  In the former, [https://physio-pedia.com/Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal rheumatoid arthritis] causes inflammation at the PIP joint.  This leads to laxity and weakness of the ligaments, joint capsule and structures designed to provide stability to the joints, allowing the PIP to be hyperextended<ref name=":5">Fox PM, Chang J. Treating the Proximal Interphalangeal Joint in Swan Neck and Boutonniere Deformities. ''Hand Clin''. 2018;34(2):167-176. doi:10.1016/j.hcl.2017.12.006</ref><ref name=":6">Dreyfus JN, Schnitzer TJ. Pathogenesis and differential diagnosis of the swan-neck deformity. ''Semin Arthritis Rheum''. 1983;13(2):200-211. doi:10.1016/0049-0172(83)90007-0</ref>.  An alternate cause of hyperextension is that the flexor tendon becomes ruptured<ref name=":4" />.  As the PIP joint becomes hyperextended, the extensor tendon becomes shortened and is less able to extend other joints.  The resulting tendon laxity leads to an inability to extend the DIP joint<ref name=":5" /><ref>Ridley WE, Xiang H, Han J, Ridley LJ. Swan neck deformity. ''J Med Imaging Radiat Oncol''. 2018;62 Suppl 1:159-160. doi:10.1111/1754-9485.31_12786</ref>.  The hyperextension of the PIP also stretches the flexors on the opposite side of the finger, causing them to pull more strongly on the distal segment.  This also leads to DIP flexion<ref name=":6" />.


The hyperextension of the PIP joint prevents the formation of a fist, impairing the person’s ability to grasp objects<ref>Elzinga K, Chung KC. Managing Swan Neck and Boutonniere Deformities. ''Clin Plast Surg''. 2019;46(3):329-337. doi:10.1016/j.cps.2019.02.006</ref>.
The hyperextension of the PIP joint prevents the formation of a fist, impairing the person’s ability to grasp objects<ref>Elzinga K, Chung KC. Managing Swan Neck and Boutonniere Deformities. ''Clin Plast Surg''. 2019;46(3):329-337. doi:10.1016/j.cps.2019.02.006</ref>.
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== Boutonniere Deformity ==
== Boutonniere Deformity ==


In Boutonniere Deformity, synovitis of the PIP joint causes joint flexion.  This may be due in part to damage to the central slip of the extensor tendon, which prevents the joint from extending<ref name=":7">Grau L, Baydoun H, Chen K, Sankary S, Amirouche F, Gonzalez M. Biomechanics of the Acute Boutonniere Deformity. The Journal of Hand Surgery. 2018;37(8):80.e1-80.e6. doi:10.1016/j.jhsa.2017.07.011</ref>.  Further destruction to the joint tissues by rheumatoid arthritis causes subluxation of the lateral bands<ref name=":7" /><ref>Ferlic DC. Boutonniere deformities in rheumatoid arthritis. ''Hand Clin''. 1989;5(2):215-222.</ref>.  The changed position  of the lateral bands means that they pull the joint into flexion, rather than extension<ref name=":7" />.  This causes secondary changes in the nearby joints, pulling the DIP joint into extension, due to tightness of the extensor tendon and the shortened flexor tendon<ref name=":8">Nalebuff EA, Millender LH. Surgical treatment of the boutonniere deformity in rheumatoid arthritis. ''Orthop Clin North Am''. 1975;6(3):753-763.</ref>.  At first the finger may be passively straightened out, but eventually it gets stuck in this position<ref name=":8" />.
In [https://physio-pedia.com/Boutonniere_Deformity?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal Boutonniere Deformity], synovitis of the [https://physio-pedia.com/Interphalangeal_Joints_of_the_Hand?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal PIP] joint causes joint flexion.  This may be due in part to damage to the [https://physio-pedia.com/Central_Slip_Extensor_Tendon_Injuries?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal central slip of the extensor tendon], which prevents the joint from extending<ref name=":7">Grau L, Baydoun H, Chen K, Sankary S, Amirouche F, Gonzalez M. Biomechanics of the Acute Boutonniere Deformity. The Journal of Hand Surgery. 2018;37(8):80.e1-80.e6. doi:10.1016/j.jhsa.2017.07.011</ref>.  Further destruction to the joint tissues by rheumatoid arthritis causes subluxation of the lateral bands<ref name=":7" /><ref>Ferlic DC. Boutonniere deformities in rheumatoid arthritis. ''Hand Clin''. 1989;5(2):215-222.</ref>.  The changed position  of the lateral bands means that they pull the joint into flexion, rather than extension<ref name=":7" />.  This causes secondary changes in the nearby joints, pulling the [https://physio-pedia.com/Interphalangeal_Joints_of_the_Hand?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal DIP] joint into extension, due to tightness of the extensor tendon and the shortened flexor tendon<ref name=":8">Nalebuff EA, Millender LH. Surgical treatment of the boutonniere deformity in rheumatoid arthritis. ''Orthop Clin North Am''. 1975;6(3):753-763.</ref>.  At first the finger may be passively straightened out, but eventually it gets stuck in this position<ref name=":8" />.


A person with a boutonniere deformity might also extend their MCP joints to compensate for PIP joint flexion<ref name=":8" />.  As rheumatoid arthritis progresses, and the deformity becomes severe, hand function can become severely limited as they cannot extend their fingers<ref name=":8" />.  However, the MCP joint arc of motion is not affected<ref>Chetta M, Burns PB, Kim HM, et al. The effect of swan neck and boutonniere deformities on the outcome of silicone metacarpophalangeal joint arthroplasty in rheumatoid arthritis. ''Plast Reconstr Surg''. 2013;132(3):597-603. doi:10.1097/PRS.0b013e31829ad1c1</ref>.
A person with a boutonniere deformity might also extend their MCP joints to compensate for [https://physio-pedia.com/Interphalangeal_Joints_of_the_Hand?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal PIP] joint flexion<ref name=":8" />.  As [https://physio-pedia.com/Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal rheumatoid arthritis] progresses, and the deformity becomes severe, hand function can become severely limited as they cannot extend their fingers<ref name=":8" />.  However, the MCP joint arc of motion is not affected<ref>Chetta M, Burns PB, Kim HM, et al. The effect of swan neck and boutonniere deformities on the outcome of silicone metacarpophalangeal joint arthroplasty in rheumatoid arthritis. ''Plast Reconstr Surg''. 2013;132(3):597-603. doi:10.1097/PRS.0b013e31829ad1c1</ref>.


== Flexor Tenosynovitis and Trigger Finger ==
== Flexor Tenosynovitis and Trigger Finger ==


Flexor tenosynovitis occurs when the synovial tendon sheath is inflamed by rheumatoid arthritis<ref>Rogier C, Hayer S, van der Helm-van Mil A. Not only synovitis but also tenosynovitis needs to be considered: why it is time to update textbook images of rheumatoid arthritis. ''Ann Rheum Dis''. 2020;79(4):546-547. doi:10.1136/annrheumdis-2019-216350</ref>.  It occurs in 55% of patients with rheumatoid arthritis<ref>Gray RG, Gottlieb NL. Hand flexor tenosynovitis in rheumatoid arthritis. Prevalence, distribution, and associated rheumatic features. ''Arthritis Rheum''. 1977;20(4):1003-1008. doi:10.1002/art.1780200414</ref>.  The inflammation and thickening of the tendon sheath can lead to secondary pathologies such as carpal tunnel syndrome<ref>Sternbach G. The carpal tunnel syndrome. ''J Emerg Med''. 1999;17(3):519-523. doi:10.1016/s0736-4679(99)00030-x</ref>.  Thickening of the tendon pullies, where the flexor tendons pass through in their hands, can lead to a condition known as trigger finger<ref name=":9">Akhtar S, Bradley MJ, Quinton DN, Burke FD. Management and referral for trigger finger/thumb. Bmj. 2005;331(7507):30-33. doi:10.1136/bmj.331.7507.30</ref><ref>Vasiliadis AV, Itsiopoulos I. Trigger Finger: An Atraumatic Medical Phenomenon. J Hand Surg Asian Pac Vol. 2017;22(2):188-193. doi:10.1142/S021881041750023X</ref>.  Patients may feel a “grinding” sense, as the flexor tendons pass through the pullies.  In earlier stages of the disease, the stronger flexors will still be able to pull the hand into flexion, but the weaker extensors will not be able to extend the fingers, as the flexor tendons are stuck in flexion.
Flexor tenosynovitis occurs when the synovial tendon sheath is inflamed by [https://physio-pedia.com/Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal rheumatoid arthritis]<ref>Rogier C, Hayer S, van der Helm-van Mil A. Not only synovitis but also tenosynovitis needs to be considered: why it is time to update textbook images of rheumatoid arthritis. ''Ann Rheum Dis''. 2020;79(4):546-547. doi:10.1136/annrheumdis-2019-216350</ref>.  It occurs in 55% of patients with [https://physio-pedia.com/Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal rheumatoid arthritis]<ref>Gray RG, Gottlieb NL. Hand flexor tenosynovitis in rheumatoid arthritis. Prevalence, distribution, and associated rheumatic features. ''Arthritis Rheum''. 1977;20(4):1003-1008. doi:10.1002/art.1780200414</ref>.  The inflammation and thickening of the tendon sheath can lead to secondary pathologies such as carpal tunnel syndrome<ref>Sternbach G. The carpal tunnel syndrome. ''J Emerg Med''. 1999;17(3):519-523. doi:10.1016/s0736-4679(99)00030-x</ref>.  Thickening of the [https://physio-pedia.com/Hand_Pulleys?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal tendon pullies], where the flexor tendons pass through in their hands, can lead to a condition known as [https://physio-pedia.com/Trigger_Finger?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal trigger finger]<ref name=":9">Akhtar S, Bradley MJ, Quinton DN, Burke FD. Management and referral for trigger finger/thumb. Bmj. 2005;331(7507):30-33. doi:10.1136/bmj.331.7507.30</ref><ref>Vasiliadis AV, Itsiopoulos I. Trigger Finger: An Atraumatic Medical Phenomenon. J Hand Surg Asian Pac Vol. 2017;22(2):188-193. doi:10.1142/S021881041750023X</ref>.  Patients may feel a “grinding” sense, as the flexor tendons pass through the pullies.  In earlier stages of the disease, the stronger flexors will still be able to pull the hand into flexion, but the weaker extensors will not be able to extend the fingers, as the flexor tendons are stuck in flexion.


In trigger finger, the condition will cause difficulty in finger flexion and extension, and the hand may eventually become stuck in flexion<ref name=":9" />.  Flexor tenosynovitis can lead to hand weakness, especially in grasps requiring strong flexion<ref name=":9" />.  Bone spurs may cause tendon rupture, leading to further hand weakness and an inability to flex the fingers impacted<ref>Mannerfelt L, Norman O. Attrition ruptures of flexor tendons in rheumatoid arthritis caused by bony spurs in the carpal tunnel. A clinical and radiological study. ''J Bone Joint Surg Br''. 1969;51(2):270-277.</ref><ref>Ertel AN, Millender LH, Nalebuff E, McKay D, Leslie B. Flexor tendon ruptures in patients with rheumatoid arthritis. ''J Hand Surg Am''. 1988;13(6):860-866. doi:10.1016/0363-5023(88)90260-2</ref>.
In [https://physio-pedia.com/Trigger_Finger?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal trigger finger], the condition will cause difficulty in finger flexion and extension, and the hand may eventually become stuck in flexion<ref name=":9" />.  Flexor tenosynovitis can lead to hand weakness, especially in grasps requiring strong flexion<ref name=":9" />.  Bone spurs may cause tendon rupture, leading to further hand weakness and an inability to flex the fingers impacted<ref>Mannerfelt L, Norman O. Attrition ruptures of flexor tendons in rheumatoid arthritis caused by bony spurs in the carpal tunnel. A clinical and radiological study. ''J Bone Joint Surg Br''. 1969;51(2):270-277.</ref><ref>Ertel AN, Millender LH, Nalebuff E, McKay D, Leslie B. Flexor tendon ruptures in patients with rheumatoid arthritis. ''J Hand Surg Am''. 1988;13(6):860-866. doi:10.1016/0363-5023(88)90260-2</ref>.


== Extensor Tendon Rupture ==
== Extensor Tendon Rupture ==


Extension tendon rupture can occur when rheumatoid arthritis causes synovial inflammation of the tendon sheaths<ref name=":10">Biehl C, Rupp M, Kern S, Heiss C, ElKhassawna T, Szalay G. Extensor tendon ruptures in rheumatoid wrists. ''Eur J Orthop Surg Traumatol''. 2020;30(8):1499-1504. doi:10.1007/s00590-020-02731-1</ref>.  This weakens the tendons, and they eventually rupture.  It can also be caused by attrition of the tendons on the ulnar head<ref>Vaughan-Jackson OJ. Rupture of extensor tendons by attrition at the inferior radio-ulnar joint; report of two cases. ''J Bone Joint Surg Br''. 1948;30B(3):528-530.</ref>.  Typically the Extensor Digiti Minimi (EDM) tendon ruptures first (excluding the thumb), so by testing for EDM function, clinicians can prevent the ruptures of the remaining tendons<ref>Williamson L, Mowat A, Burge P. Screening for extensor tendon rupture in rheumatoid arthritis. ''Rheumatology (Oxford)''. 2001;40(4):420-423. doi:10.1093/rheumatology/40.4.420</ref>.
[https://physio-pedia.com/Extensor_Tendon_Injuries_of_the_Hand?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal Extension tendon rupture] can occur when [https://physio-pedia.com/Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal rheumatoid arthritis] causes synovial inflammation of the tendon sheaths<ref name=":10">Biehl C, Rupp M, Kern S, Heiss C, ElKhassawna T, Szalay G. Extensor tendon ruptures in rheumatoid wrists. ''Eur J Orthop Surg Traumatol''. 2020;30(8):1499-1504. doi:10.1007/s00590-020-02731-1</ref>.  This weakens the tendons, and they eventually rupture.  It can also be caused by attrition of the tendons on the ulnar head<ref>Vaughan-Jackson OJ. Rupture of extensor tendons by attrition at the inferior radio-ulnar joint; report of two cases. ''J Bone Joint Surg Br''. 1948;30B(3):528-530.</ref>.  Typically the Extensor Digiti Minimi (EDM) tendon ruptures first (excluding the thumb), so by testing for EDM function, clinicians can prevent the ruptures of the remaining tendons<ref>Williamson L, Mowat A, Burge P. Screening for extensor tendon rupture in rheumatoid arthritis. ''Rheumatology (Oxford)''. 2001;40(4):420-423. doi:10.1093/rheumatology/40.4.420</ref>.


Extensor tendon rupture can lead to malpositioning of the fingers and painful movement, eventually causing stiffness as motion is limited<ref name=":10" />.  However, patients learn to adapt as the function degenerates, and it may not be as obvious as an acute rupture<ref name=":10" />.
Extensor tendon rupture can lead to malpositioning of the fingers and painful movement, eventually causing stiffness as motion is limited<ref name=":10" />.  However, patients learn to adapt as the function degenerates, and it may not be as obvious as an acute rupture<ref name=":10" />.
Line 46: Line 46:
== Opera Glass Hand ==
== Opera Glass Hand ==


In extreme cases, rheumatoid arthritis can lead to bone reabsorption and shortening.  This starts at the articular surfaces, and as it progresses, bones become shorter<ref name=":11">Nalebuff EA, Garrett J. Opera-glass hand in rheumatoid arthritis. ''J Hand Surg Am''. 1976;1(3):210-220. doi:10.1016/s0363-5023(76)80040-8</ref>.  In a healthy hand, the flexor and extensor tendons pull the distal segments into the proximal segments, creating stability, along with the shear force that they produce that causes rotation around the joint.  In the opera glass hand, this compressive force pulls the shortened bones into the hand, leading to collapse of the fingers in a manner similar to how an opera glass might be collapsed into itself.  The combination of the bone reabsorption, and external and internal forces can also lead to dislocation<ref name=":11" />.
In extreme cases, [https://physio-pedia.com/Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal rheumatoid arthritis] can lead to bone reabsorption and shortening.  This starts at the [https://physio-pedia.com/Joint_Classification?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal articular surfaces], and as it progresses, bones become shorter<ref name=":11">Nalebuff EA, Garrett J. Opera-glass hand in rheumatoid arthritis. ''J Hand Surg Am''. 1976;1(3):210-220. doi:10.1016/s0363-5023(76)80040-8</ref>.  In a healthy hand, the flexor and extensor tendons pull the distal segments into the proximal segments, creating stability, along with the shear force that they produce that causes rotation around the joint.  In the opera glass hand, this compressive force pulls the shortened bones into the hand, leading to collapse of the fingers in a manner similar to how an opera glass might be collapsed into itself.  The combination of the bone reabsorption, and external and internal forces can also lead to dislocation<ref name=":11" />.


This deformity causes significant disability.  The collapse shortens the span of the fingers, creating a smaller arc of grasp, but unequal shortening between the fingers can also make it difficult to use them<ref name=":11" />.  The bone reabsorption at the joint causes profound instability, and also angular deformity<ref name=":11" />.  All of these factors make it difficult to complete activities of daily living.
This deformity causes significant disability.  The collapse shortens the span of the fingers, creating a smaller arc of grasp, but unequal shortening between the fingers can also make it difficult to use them<ref name=":11" />.  The bone reabsorption at the joint causes profound instability, and also angular deformity<ref name=":11" />.  All of these factors make it difficult to complete [https://physio-pedia.com/ADLs?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal activities of daily living].


== Conclusion and Further Resources ==
== Conclusion and Further Resources ==


Without the appropriate intervention, deformities caused by rheumatoid arthritis will continue to worsen and cause functional issues for the person suffering from the disease.  Fortunately there continues to be a great deal of research and development of interventions for both rheumatoid arthritis and each deformity individually.  Furthermore, physical therapy can improve the hand function that each person requires to complete their activities of daily living, and also introduce behavioral modifications to decrease joint loading (H.R.A on Physiopedia).  For more information on rheumatoid arthritis and its rehabilitation, consider the following resources:
Without the appropriate intervention, deformities caused by [https://physio-pedia.com/Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal rheumatoid arthritis] will continue to worsen and cause functional issues for the person suffering from the disease.  Fortunately there continues to be a great deal of research and development of interventions for both rheumatoid arthritis and each deformity individually.  Furthermore, physical therapy can improve the hand function that each person requires to complete their activities of daily living, and also introduce behavioral [https://physio-pedia.com/Hand_Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal modifications to decrease joint loading].  For more information on [https://physio-pedia.com/Hand_Rheumatoid_Arthritis?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal hand rheumatoid arthritis and its rehabilitation], consider the following resources:
* The American College of Rheumatology<ref>American College of Rheumatology. rheumatology.org. <nowiki>https://www.rheumatology.org/</nowiki>. Accessed April 13, 2021.</ref>
* [https://www.rheumatology.org/ The American College of Rheumatology]
* Kelley and Firestein’s Textbook of Rheumatology<ref>Firestein GS, Budd RC, Gabriel SE, McInnes IB, O'Dell JR, eds. ''Kelley and Firestein's Textbook of Rheumatology''. 10th ed. Elsevier; 2017.</ref>
* Kelley and Firestein’s Textbook of Rheumatology<ref>Firestein GS, Budd RC, Gabriel SE, McInnes IB, O'Dell JR, eds. ''Kelley and Firestein's Textbook of Rheumatology''. 10th ed. Elsevier; 2017.</ref>
* Essentials of Physical Medicine and Rehabilitation<ref>Frontera WR, Silver JK, Rizzo TD. ''Essentials of Physical Medicine and Rehabilitation''. 4th ed. Elsevier; 2020.</ref>
* Essentials of Physical Medicine and Rehabilitation<ref>Frontera WR, Silver JK, Rizzo TD. ''Essentials of Physical Medicine and Rehabilitation''. 4th ed. Elsevier; 2020.</ref>

Revision as of 19:43, 13 April 2021

Overview[edit | edit source]

The structure of the hand provides a great deal of insight into its function. Its multi-joint structure allows the hand to convey forces while simultaneously allowing for intricate movements at the fingers. The carpal tunnel in the wrist allows a large range of motion to finely position the hand in space, without crushing the tendons that are transmitting forces from the large forearm muscles to the hand. As these structures are damaged by rheumatoid arthritis, their capacity to perform their function decreases, severely limiting a person’s ability to adequately complete activities of daily living.

Rheumatoid Arthritis is a systemic, inflammatory disease that can severely compromise hand and wrist function. It is caused by the inflammation of the synovium, which not only lines the many synovial joints in the hand, leading to stiffness and deformity, but also surrounds the tendons that transmit force from the forearm to the fingers. This can cause tendon rupture and inflammation, leading to further weakness and deformity in the hand.

This article examines the biomechanics of the hand in patients with rheumatoid arthritis. It explores the pathogenesis of a variety of hand deformities caused by rheumatoid arthritis, before briefly outlining how this changes hand function.

Radial Deviation and Ulnar Drift[edit | edit source]

Radial deviation of the wrist and ulnar drift at the carpometacarpal joint tend to happen simultaneously[1]. The more that the wrist is deviated radially, the more the fingers deviate in the ulnar direction[2]. This is thought to be due to the biomechanics of the hand as an intercalated segment. The muscles pull the distal bones proximally, causing a collapse into a zig-zag deformity[3]. Typically this deviation gets more extreme as the disease worsens[3]. Other prominent theories of the mechanism of ulnar drift include collateral ligament laxity allowing the drift, increased intra-articular pressure causing deformity, and muscle imbalance[4]. Many activities of daily living also pull the fingers in the ulnar direction, such as holding a cup of coffee[5]. These activities may increase ulnar drift, especially if rheumatoid arthritis is already causing joint laxity[4].

The main casualty of this deformity is the loss of a range of motion at the wrist[4]. Although patients can still carry out activities of daily living, they may have to compensate for the lack of wrist motion in other ways[4].

Z Deformity of the Thumb[edit | edit source]

Synovitis of the joint capsule at the metacarpophalangeal (MCP) joint of the thumb causes weakening of the capsule and its ligament[6]. The resulting stretching of Extensor Pollicis Brevis (EPB) allows the Extensor Pollicis Longus (EPL) tendon to sublax[7]. It has also been suggested that the insertion point of EPB may contribute to this disorder[7]. The new volar placement of the tendon forces the MCP joint into flexion, secondarily causing the interphalangeal (IP) joint to hyperextend[6].

Z deformity of the thumb prevents pinching because the force of the tendons causes the thumb to collapse into MCP flexion and IP hyperextension[6]. Thumb function is important for opposition, which is essential for pinches and grips[8][9]. This deformity, therefore, can severely interrupt activities of daily living requiring opposition.

Swan Neck Deformity[edit | edit source]

Swan neck deformity can either be caused by flexion at the Distal Interphalangeal (DIP) joint, or by hyperextension at the Proximal Interphalangeal (PIP) joint[10]. In the former, arthritic weakening of the extensor tendon at the DIP causes either stretching or rupture, and the tendon is unable to extend the distal segment[10]. In the former, rheumatoid arthritis causes inflammation at the PIP joint. This leads to laxity and weakness of the ligaments, joint capsule and structures designed to provide stability to the joints, allowing the PIP to be hyperextended[11][12]. An alternate cause of hyperextension is that the flexor tendon becomes ruptured[10]. As the PIP joint becomes hyperextended, the extensor tendon becomes shortened and is less able to extend other joints. The resulting tendon laxity leads to an inability to extend the DIP joint[11][13]. The hyperextension of the PIP also stretches the flexors on the opposite side of the finger, causing them to pull more strongly on the distal segment. This also leads to DIP flexion[12].

The hyperextension of the PIP joint prevents the formation of a fist, impairing the person’s ability to grasp objects[14].

Boutonniere Deformity[edit | edit source]

In Boutonniere Deformity, synovitis of the PIP joint causes joint flexion. This may be due in part to damage to the central slip of the extensor tendon, which prevents the joint from extending[15]. Further destruction to the joint tissues by rheumatoid arthritis causes subluxation of the lateral bands[15][16]. The changed position of the lateral bands means that they pull the joint into flexion, rather than extension[15]. This causes secondary changes in the nearby joints, pulling the DIP joint into extension, due to tightness of the extensor tendon and the shortened flexor tendon[17]. At first the finger may be passively straightened out, but eventually it gets stuck in this position[17].

A person with a boutonniere deformity might also extend their MCP joints to compensate for PIP joint flexion[17]. As rheumatoid arthritis progresses, and the deformity becomes severe, hand function can become severely limited as they cannot extend their fingers[17]. However, the MCP joint arc of motion is not affected[18].

Flexor Tenosynovitis and Trigger Finger[edit | edit source]

Flexor tenosynovitis occurs when the synovial tendon sheath is inflamed by rheumatoid arthritis[19]. It occurs in 55% of patients with rheumatoid arthritis[20]. The inflammation and thickening of the tendon sheath can lead to secondary pathologies such as carpal tunnel syndrome[21]. Thickening of the tendon pullies, where the flexor tendons pass through in their hands, can lead to a condition known as trigger finger[22][23]. Patients may feel a “grinding” sense, as the flexor tendons pass through the pullies. In earlier stages of the disease, the stronger flexors will still be able to pull the hand into flexion, but the weaker extensors will not be able to extend the fingers, as the flexor tendons are stuck in flexion.

In trigger finger, the condition will cause difficulty in finger flexion and extension, and the hand may eventually become stuck in flexion[22]. Flexor tenosynovitis can lead to hand weakness, especially in grasps requiring strong flexion[22]. Bone spurs may cause tendon rupture, leading to further hand weakness and an inability to flex the fingers impacted[24][25].

Extensor Tendon Rupture[edit | edit source]

Extension tendon rupture can occur when rheumatoid arthritis causes synovial inflammation of the tendon sheaths[26]. This weakens the tendons, and they eventually rupture. It can also be caused by attrition of the tendons on the ulnar head[27]. Typically the Extensor Digiti Minimi (EDM) tendon ruptures first (excluding the thumb), so by testing for EDM function, clinicians can prevent the ruptures of the remaining tendons[28].

Extensor tendon rupture can lead to malpositioning of the fingers and painful movement, eventually causing stiffness as motion is limited[26]. However, patients learn to adapt as the function degenerates, and it may not be as obvious as an acute rupture[26].

Opera Glass Hand[edit | edit source]

In extreme cases, rheumatoid arthritis can lead to bone reabsorption and shortening. This starts at the articular surfaces, and as it progresses, bones become shorter[29]. In a healthy hand, the flexor and extensor tendons pull the distal segments into the proximal segments, creating stability, along with the shear force that they produce that causes rotation around the joint. In the opera glass hand, this compressive force pulls the shortened bones into the hand, leading to collapse of the fingers in a manner similar to how an opera glass might be collapsed into itself. The combination of the bone reabsorption, and external and internal forces can also lead to dislocation[29].

This deformity causes significant disability. The collapse shortens the span of the fingers, creating a smaller arc of grasp, but unequal shortening between the fingers can also make it difficult to use them[29]. The bone reabsorption at the joint causes profound instability, and also angular deformity[29]. All of these factors make it difficult to complete activities of daily living.

Conclusion and Further Resources[edit | edit source]

Without the appropriate intervention, deformities caused by rheumatoid arthritis will continue to worsen and cause functional issues for the person suffering from the disease. Fortunately there continues to be a great deal of research and development of interventions for both rheumatoid arthritis and each deformity individually. Furthermore, physical therapy can improve the hand function that each person requires to complete their activities of daily living, and also introduce behavioral modifications to decrease joint loading. For more information on hand rheumatoid arthritis and its rehabilitation, consider the following resources:

References[edit | edit source]

  1. ↑ Pahle JA, Raunio P. The influence of wrist position on finger deviation in the rheumatoid hand. A clinical and radiological study. J Bone Joint Surg Br. 1969;51(4):664-676.
  2. ↑ Dibenedetto MR, Lubbers LM, Coleman CR. Relationship between radial inclination angle and ulnar deviation of the fingers. The Journal of Hand Surgery. 1991;16(1):36-39. doi:10.1016/s0363-5023(10)80009-7
  3. ↑ 3.0 3.1 Read GO, Solomon L, Biddulph S. Relationship between finger and wrist deformities in rheumatoid arthritis. Annals of the Rheumatic Diseases. 1983;42(6):619-625. doi:10.1136/ard.42.6.619
  4. ↑ 4.0 4.1 4.2 4.3 Morco S, Bowden A. Ulnar drift in rheumatoid arthritis: a review of biomechanical etiology. Journal of Biomechanics. 2015;48(4):725-728. doi:10.1016/j.jbiomech.2014.12.052 Morco S, Bowden A. Ulnar drift in rheumatoid arthritis: a review of biomechanical etiology. Journal of Biomechanics. 2015;48(4):725-728. doi:10.1016/j.jbiomech.2014.12.052
  5. ↑ Bielefeld T, Neumann DA. The Unstable Metacarpophalangeal Joint in Rheumatoid Arthritis: Anatomy, Pathomechanics, and Physical Rehabilitation Considerations. Journal of Orthopaedic and Sports Physical Therapy. 2005;35(8):477-549. doi:10.2519/jospt.2005.35.8.502
  6. ↑ 6.0 6.1 6.2 Dyer GSM, Simmons BP. Rheumatoid Thumb. Hand Clinics. 2011;27(1):73-77. doi:10.1016/j.hcl.2010.10.001
  7. ↑ 7.0 7.1 Okita S, Nishida K, Ohtsuka A, Ozaki T. A high incidence of extensor pollicis brevis insertion into the distal phalanx in rheumatoid arthritis patients who required the surgical reconstruction for thumb boutonnière deformity. Mod Rheumatol. 2019;29(6):954-958. doi:10.1080/14397595.2018.1532484
  8. ↑ Duncan SF, Saracevic CE, Kakinoki R. Biomechanics of the Hand. Hand Clinics. 2013;29(4):483-492. doi:10.1016/j.hcl.2013.08.003
  9. ↑ Imaeda T, An KN, Cooney WP 3rd. Functional anatomy and biomechanics of the thumb. Hand Clin. 1992;8(1):9-15.
  10. ↑ 10.0 10.1 10.2 Nalebuff EA. The Rheumatoid Swan-Neck Deformity. Hand Clinics. 1989;5(2):203-214.
  11. ↑ 11.0 11.1 Fox PM, Chang J. Treating the Proximal Interphalangeal Joint in Swan Neck and Boutonniere Deformities. Hand Clin. 2018;34(2):167-176. doi:10.1016/j.hcl.2017.12.006
  12. ↑ 12.0 12.1 Dreyfus JN, Schnitzer TJ. Pathogenesis and differential diagnosis of the swan-neck deformity. Semin Arthritis Rheum. 1983;13(2):200-211. doi:10.1016/0049-0172(83)90007-0
  13. ↑ Ridley WE, Xiang H, Han J, Ridley LJ. Swan neck deformity. J Med Imaging Radiat Oncol. 2018;62 Suppl 1:159-160. doi:10.1111/1754-9485.31_12786
  14. ↑ Elzinga K, Chung KC. Managing Swan Neck and Boutonniere Deformities. Clin Plast Surg. 2019;46(3):329-337. doi:10.1016/j.cps.2019.02.006
  15. ↑ 15.0 15.1 15.2 Grau L, Baydoun H, Chen K, Sankary S, Amirouche F, Gonzalez M. Biomechanics of the Acute Boutonniere Deformity. The Journal of Hand Surgery. 2018;37(8):80.e1-80.e6. doi:10.1016/j.jhsa.2017.07.011
  16. ↑ Ferlic DC. Boutonniere deformities in rheumatoid arthritis. Hand Clin. 1989;5(2):215-222.
  17. ↑ 17.0 17.1 17.2 17.3 Nalebuff EA, Millender LH. Surgical treatment of the boutonniere deformity in rheumatoid arthritis. Orthop Clin North Am. 1975;6(3):753-763.
  18. ↑ Chetta M, Burns PB, Kim HM, et al. The effect of swan neck and boutonniere deformities on the outcome of silicone metacarpophalangeal joint arthroplasty in rheumatoid arthritis. Plast Reconstr Surg. 2013;132(3):597-603. doi:10.1097/PRS.0b013e31829ad1c1
  19. ↑ Rogier C, Hayer S, van der Helm-van Mil A. Not only synovitis but also tenosynovitis needs to be considered: why it is time to update textbook images of rheumatoid arthritis. Ann Rheum Dis. 2020;79(4):546-547. doi:10.1136/annrheumdis-2019-216350
  20. ↑ Gray RG, Gottlieb NL. Hand flexor tenosynovitis in rheumatoid arthritis. Prevalence, distribution, and associated rheumatic features. Arthritis Rheum. 1977;20(4):1003-1008. doi:10.1002/art.1780200414
  21. ↑ Sternbach G. The carpal tunnel syndrome. J Emerg Med. 1999;17(3):519-523. doi:10.1016/s0736-4679(99)00030-x
  22. ↑ 22.0 22.1 22.2 Akhtar S, Bradley MJ, Quinton DN, Burke FD. Management and referral for trigger finger/thumb. Bmj. 2005;331(7507):30-33. doi:10.1136/bmj.331.7507.30
  23. ↑ Vasiliadis AV, Itsiopoulos I. Trigger Finger: An Atraumatic Medical Phenomenon. J Hand Surg Asian Pac Vol. 2017;22(2):188-193. doi:10.1142/S021881041750023X
  24. ↑ Mannerfelt L, Norman O. Attrition ruptures of flexor tendons in rheumatoid arthritis caused by bony spurs in the carpal tunnel. A clinical and radiological study. J Bone Joint Surg Br. 1969;51(2):270-277.
  25. ↑ Ertel AN, Millender LH, Nalebuff E, McKay D, Leslie B. Flexor tendon ruptures in patients with rheumatoid arthritis. J Hand Surg Am. 1988;13(6):860-866. doi:10.1016/0363-5023(88)90260-2
  26. ↑ 26.0 26.1 26.2 Biehl C, Rupp M, Kern S, Heiss C, ElKhassawna T, Szalay G. Extensor tendon ruptures in rheumatoid wrists. Eur J Orthop Surg Traumatol. 2020;30(8):1499-1504. doi:10.1007/s00590-020-02731-1
  27. ↑ Vaughan-Jackson OJ. Rupture of extensor tendons by attrition at the inferior radio-ulnar joint; report of two cases. J Bone Joint Surg Br. 1948;30B(3):528-530.
  28. ↑ Williamson L, Mowat A, Burge P. Screening for extensor tendon rupture in rheumatoid arthritis. Rheumatology (Oxford). 2001;40(4):420-423. doi:10.1093/rheumatology/40.4.420
  29. ↑ 29.0 29.1 29.2 29.3 Nalebuff EA, Garrett J. Opera-glass hand in rheumatoid arthritis. J Hand Surg Am. 1976;1(3):210-220. doi:10.1016/s0363-5023(76)80040-8
  30. ↑ Firestein GS, Budd RC, Gabriel SE, McInnes IB, O'Dell JR, eds. Kelley and Firestein's Textbook of Rheumatology. 10th ed. Elsevier; 2017.
  31. ↑ Frontera WR, Silver JK, Rizzo TD. Essentials of Physical Medicine and Rehabilitation. 4th ed. Elsevier; 2020.
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