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Continuous Passive Motion (CPM)

Original Editor - Angeliki Chorti Top Contributors - Nupur Smit Shah, Angeliki Chorti, Alexandra Stead, Vidya Acharya and Lucinda hampton

Introduction

Continuous passive movement (CPM) involves applying machine assisted regular movement to a joint. The machine moves the joint passively and repetitively through a specified range of motion, with the patient contributing no active effort during the treatment.[1] CPM machines are most commonly applied to the knee, though can be used for other joints such as the hip, shoulder and elbow and is typically introduced at an early stage of rehabilitation.[2] Machine use also accelerates the reduction of pain and swelling postoperatively. [3]

Indications

CPM is most commonly used after joint surgery, such as total knee arthroplasty or articular cartilage repair, to help manage thromboprophylaxis and promote the recovery of normal joint range of motion (ROM) in the early postoperative stage.[2] It is also used in paediatric orthopaedic surgeries or injuries for maintaining hip and knee range of motion.[4] CPM does not interfere with open wounds, nursing care or external fixation.[4]

CPM is also indicated following other surgical interventions, which may include:[5][6]

  • Open reduction internal fixation of fractures
  • Synovectomy
  • Ligament reconstruction
  • Total joint replacement
  • Release of extraarticular contractures

Application of CPM

CPM has been reported to reduce swelling, promote faster return of joint mobility and reduce the need for analgesic medication.

Joint stiffness after surgery or injury is reported to progress through four stages: bleeding, oedema, granulation tissue, and fibrosis.[7] When applied during the first two stages, CPM can enable the maintenance of normal periarticular soft tissue compliance and prevent the development of stiffness by helping pump blood and oedema fluid away from the joint and periarticular tissue.[7] [8] CPM is thought to have a positive biological effect on healing of the tissue, oedema and hematoma.[2] Vasileiadis et al. suggested that CPM is also useful to stop the growth of heterotopic ossification and improve the joint mobility.[9] Moreover, whilst majority of studies have found some benefit in early rehabilitation, CPM should not be used as a substitute to physiotherapy treatment or the only intervention as part of a management plan, as it may only lead to short term gains range of movement without long term functional benefits.[10]

Duration

The timing of CPM initiation, the duration of each session, the total period of CPM application and its effect on long-term outcomes remains controversial.[2][8] [11] A 2014 Cochrane review states that short-term use of CPM offers greater short-term ROM benefits, but long-term improvements are yet to be demonstrated to justify its routine use.[1] A more recent systematic review by Yang et al., also suggested that evidence favouring the routine use of CPM machines is still lacking.[12] Within the limited evidence base, it is suggested that short-term use is sufficient at achieving short term gain in range of motion, though prolonged CPM may also lead to short term gains.[13] However, when weighing up clinical application of CPM, it is important to consider factors such as the preoperative ROM of the patient, postoperative day of CPM initiation, daily ROM increment, and total number of sessions.[10]

Contraindications

When considering using CPM machines, there are a number of contraindications to be aware of:[10][14]

  • Deep Vein Thrombosis
  • Acute inflammation
  • Severe osteoporosis
  • Cardiovascular disease or neuromuscular disease
  • Cognitive deficits
  • Severe obesity - BMI>35 kg/m2
  • Severe pain
  • Spastic Disorders
  • Bleeding disorders or the use of anticoagulants

Clinical Relevance

Patient selection

CPM is usually used for patients at high risk of stiffness or unable to mobilise early on actively,such as those with poor pre-operative range of motion, history of arthrofibrosis or restricted weight bearing after complex surgical intervention.[1]

Protocol Specific Considerations

After cartilage repair, the rationale is that motion supports repair tissue during the non-weight bearing period. But only four studies were available in one systematic review due to which authors were unable to draw definitive conclusions despite strong basic science support.[15]

Evidence Gaps

Optimal start time, duration, speed and range of motion progression remain unstandardised.[2] A 2025 pilot study developed a robotic CPM device for frozen shoulder that also measures joint stiffness during use. Passive ROM exercise is widely used for frozen shoulder, but it depends on therapist time and cost. A CPM device that delivers a comparable effect could widen access, particularly for patients who cannot attend frequent sessions.The authors state that validation in home settings is still needed.[16]Further studies should also focus on consistent protocols and long term reporting of the function rather than range of motion alone.

Summary

Continuous Passive Motion (CPM) is a rehabilitation technique in which a motorised device moves a joint passively through a controlled range of motion, most commonly used after knee surgery such as total knee arthroplasty. The rationale is that early, controlled movement in the immediate post-operative period may reduce stiffness, limit scar tissue formation, and support tissue healing during the phase when patients cannot yet move the joint actively on their own.

References

  1. ↑ 1.0 1.1 1.2 Harvey L.A., Brosseau L., Herbert R.D. Continuous passive motion following total knee arthroplasty in people with arthritis. Cochrane Database Syst Rev. 2014 Feb 6;(2):CD004260.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 He M.L., Xiao Z.M., Lei M., Li TS.., Wu H., Liao J. Continuous passive motion for preventing venous thromboembolism after total knee arthroplasty. Cochrane Database Syst Rev. 2014 Jul 29;(7):CD008207.
  3. ↑ Wang X, Liu Q, Tan J, Wu J, Yang H, Xiong F, Ying Q, Mi J. Optimizing continuous passive motion duration following arthroscopic release of elbow contracture: a retrospective study. BMC Musculoskeletal Disorders. 2024 Nov 26;25(1):965.
  4. ↑ 4.0 4.1 Guidera K.J., Hontas R., Ogden J.A. Use of continuous passive motion in pediatric orthopedics. J Pediatr Orthop. 1990 Jan-Feb;10(1):120-3.
  5. ↑ O'Driscoll SW, Giori NJ. M Affairs. Journal of Rehabilitation Research & Development. 2000;37(2):179-88.
  6. ↑ Wang X, Liu Q, Tan J, Wu J, Yang H, Xiong F, Ying Q, Mi J. Optimizing continuous passive motion duration following arthroscopic release of elbow contracture: a retrospective study. BMC Musculoskeletal Disorders. 2024 Nov 26;25(1):965.
  7. ↑ 7.0 7.1 O'Driscoll SW, Giori NJ. Continuous passive motion (CPM): theory and principles of clinical application. J Rehabil Res Dev. 2000 Mar-Apr;37(2):179-88. Erratum in: J Rehabil Res Dev 2001 Mar-Apr;38(2):291.
  8. ↑ 8.0 8.1 Gil-González S., Barja-Rodríguez R., López-Pujol A., Berjaoui H., Fernández-Bengoa J., Erquicia J., Leal-Blanquet J., Pelfort X. Continuous passive motion not affect the knee motion and the surgical wound aspect after total knee arthroplasty. J Orthop Surg Res. 2022 Jan 15;17(1):25.
  9. ↑ Vasileiadis GI, Varvarousis DN, Manolis I, Ploumis A. The impact of continuous passive motion on heterotopic ossification maturation. American Journal of Physical Medicine & Rehabilitation. 2021 Dec 1;100(12):e194-7.
  10. ↑ 10.0 10.1 10.2 Liao C., Tsauo J., Huang S., Chen H., Chiu Y., Liou T. Preoperative range of motion and applications of continuous passive motion predict outcomes after knee arthroplasty in patients with arthritis. Knee Surg Sports Traumatol Arthrosc. 2019 Apr;27(4):1259-1269.
  11. ↑ Lenssen T.A., van Steyn M.J., Crijns Y.H., Waltjé E.M., Roox G.M., Geesink R.J., van den Brandt P.A., De Bie R.A. Effectiveness of prolonged use of continuous passive motion (CPM), as an adjunct to physiotherapy, after total knee arthroplasty. BMC Musculoskelet Disord. 2008 Apr 29;9:60.
  12. ↑ Yang X., Li G., Wang H., Wang C. Continuous Passive Motion After Total Knee Arthroplasty: A Systematic Review and Meta-analysis of Associated Effects on Clinical Outcomes. Arch Phys Med Rehabil. 2019 Sep;100(9):1763-1778.
  13. ↑ Lenssen TA, van Steyn MJ, Crijns YH, Waltjé EM, Roox GM, Geesink RJ, Brandt PA, De Bie RA. Effectiveness of prolonged use of continuous passive motion (CPM), as an adjunct to physiotherapy, after total knee arthroplasty. BMC Musculoskeletal Disorders. 2008 Apr 29;9(1):60.
  14. ↑ Lee BC, Moon CW, Choi WS, Kim YM, Joo YB, Lee DG, Lee SJ, Choi E, Ji JH, Suh DW, Cho KH. Clinical evaluation of usefulness and effectiveness of sitting-type continuous passive motion machines in patients with total knee arthroplasty: a dual-center randomized controlled trial. BMC musculoskeletal disorders. 2024 Dec 19;25(1):1039.
  15. ↑ Fazalare JA, Griesser MJ, Siston RA, Flanigan DC. The use of continuous passive motion following knee cartilage defect surgery: a systematic review. Orthopedics. 2010;33(12):878
  16. ↑ Lee J, Yun S-S, Oh KR, Chung SG, Hwang W, Kim K, Cho K-J. Development and validation of a sliding type continuous passive motion automation device for evaluation and rehabilitation of frozen shoulder: a pilot study. Front Rehabil Sci. 2025;6:1639249. doi: 10.3389/fresc.2025.1639249
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