Dorsal radioulnar ligament
Description[edit | edit source]
The dorsal radioulnar ligament (DRUL) is comprised of parallel collagen bundles dividing into deep and superficial limbs, which attach into the fovea and ulnar styloid, spanning across the radius and ulna and forming ,among other structures, the triangular fibrocartilage complex (TFCC) located on the ulnar aspect of the wrist joint between the lunate, triquetrum, and ulnar head. 
Attachment[edit | edit source]
The DRUL connects the posterior margin of the ulnar notch at the distal radius to the posterior portion of the head of the ulna. The ligament is innervated by the anterior and posterior interosseous nerves and the anterior interosseous artery provides her blood supply.
Function[edit | edit source]
DRUL acts along with the palmar(volar) radioulnar ligament as a primary stabilizer of the dorsal radioulnar joint (DRUJ) and as a shock absorber across the ulna-carpal joint.  However, in pronation DRUL is more critical in stabilizing the DRUJ than the palmar radioulnar ligament. 
Clinical Relevance[edit | edit source]
Traumatic or degenerative injuries can occur for several reasons including aging, due to the complexity of the anatomical structure and the way load transmission takes place around the ulnar aspect of the wrist joint. Injury often occurs under forced ulnar deviation. Repetitive forearm rotation, in particular, leads to overuse of DRUL which leads to degenerative changes. The second most common injury mechanism involving the DRUL is forced forearm rotation. The injury prevalence in patients aged 70 or older is 49% and 27% in patients aged 30 or younger.  The DRUL injuries are associated with damage involving the TFCC or other radioulnar ligaments resulting from distal radius fractures, fractures of the ulnar styloid, and eponymous Galeazzi or Essex Lopresti fractures. Injury to the interosseous membrane (IOM) can also put a lot of strain on the DRUL and may consequently can cause injury to the DRUL. 
Assessment[edit | edit source]
The latest study is reports that computed tomographic arthrography is the most sensitive and specific diagnostic tool to detect TFCC lesions. 
Subjective[edit | edit source]
Patients may complain of dull ulnar-sided wrist pain often worsening with activity, particularly during forearm rotation. However, difficulty carrying loads is the hallmark of injury to the DRUL. As brevity and simplicity is beneficial in the clinical environment, wrist pain and disability can be measured with the PRWE questionnaire.
Physical Examination[edit | edit source]
Pain is accompanied by clicking or tender points between the pisiform and the ulnar head. The physical examination reveals Muscle weakness in the grip, supination and pronation, which can indicate wrist instability. 
There is no specific test for the DRUL but several physical exams testing the TFCC can possibly indicate injury to the DRUL and rule out the possibility of fractures .
- TFCC compression test: Pain is reproduced with ulnar deviation whilst forearm is in the neutral position.
- TFCC stress test: Pain is reproduced whilst applying force across the ulnar while the wrist in ulnar deviation .
- Press test: Pain is reproduced when the patient lifts themselves out of a chair using the wrists is in an extended position.
- Supination test: Pain is reproduced when the patient grabs the underside of a table with the forearms supinated.
- Piano key test: Pain and excessive movement are reproduced whilst the wrist in pronation, stabilizing the wrist and the radius in one hand and at the same time pressing anteroposterior with the other hand on the distal ulnar styloid process.
Treatment[edit | edit source]
- It is important to identify the daily activities aggravating the pain and modify them with the help of professionals such as physiotherapists.
- Allow rest and completely avoid sports activities that consist of full weight bearing on the wrist while performing manoeuvre movements such as Yoga poses etc.
- Application of temporary splint or cast.
- The use of NSAIDs.
- Administration of corticosteroid injection in conjunction with physical therapy in extremely symptomatic patients.
- Patient should consult an occupational therapist or hand therapist to improve range of motion and strengthen muscles. 
- Arthroscopy or open surgical procedure is performed when conservative treatment fails to alleviate symptoms, or in cases presenting initially with instability of the DRUJ, unstable and displaced fractures or changes in the ulna length. In most, if not all conditions involving TFCC, surgical management can be conducted successfully. 
References[edit | edit source]
- Pulos N, Bozentka DJ. Carpal ligament anatomy and biomechanics. Hand Clinics. 2015 Aug 1;31(3):381-7.
- Jawed A, Ansari MT, Gupta V. TFCC injuries: How we treat?. Journal of Clinical Orthopaedics and Trauma. 2020 Jul 1;11(4):570-9.
- Moore KL, Dalley AF, Agur AMR. Clinically oriented anatomy. Lippincott Williams and Wilkins. ISBN:0781775256. Read it at Google Books - Find it at Amazon
- MIKIC Ž. The blood supply of the human distal radioulnar joint and the microvasculature of its articular disk. Clinical Orthopaedics and Related Research®. 1992 Feb 1;275:19-28.
- Casadei K, Kiel J. Triangular Fibrocartilage Complex.
- Moritomo H. Advantages of open repair of a foveal tear of the triangular fibrocartilage complex via a palmar surgical approach. Tech Hand Upper Extrem Surg. 2009;13:176–81. doi: 10.1097/BTH.0b013e3181bd8319
- Kihara H, Short WH, Werner FW, Fortino MD, Palmer AK. The stabilizing mechanism of the distal radioulnar joint during pronation and supination. The Journal of hand surgery. 1995 Nov 1;20(6):930-6.
- Moritomo H, Masatomi T, Murase T, Miyake JI, Okada K, Yoshikawa H. Open repair of foveal avulsion of the triangular fibrocartilage complex and comparison by types of injury mechanism. The Journal of hand surgery. 2010 Dec 1;35(12):1955-63.
- Werner FW, LeVasseur MR, Harley BJ, Anderson A. Role of the interosseous membrane in preventing distal radioulnar gapping. Journal of Wrist Surgery. 2017 May;6(02):097-101.
- Thomas BP, Sreekanth R. Distal radioulnar joint injuries. Indian journal of orthopaedics. 2012 Oct;46(5):493-504.
- Srinivasan RC, Shrouder-Henry JJ, Richard MJ, Ruch DS. Open and Arthroscopic Triangular Fibrocartilage Complex (TFCC) Repair. JAAOS-Journal of the American Academy of Orthopaedic Surgeons. 2021 Jun 15;29(12):518-25.
- Altman E. The ulnar side of the wrist: clinically relevant anatomy and biomechanics. Journal of Hand Therapy. 2016 Apr 1;29(2):111-22.
- MacDermid JC, Turgeon T, Richards RS, Beadle M, Roth JH. Patient rating of wrist pain and disability: a reliable and valid measurement tool. Journal of orthopaedic trauma. 1998 Nov 1;12(8):577-86.