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SPRAIN, MP JOINT

Introduction

Injuries to the metacarpophalangeal (MP) joints of the fingers—particularly those involving the collateral ligaments—are less common than those occurring in the thumb MP joint and proximal interphalangeal (PIP) joints. MP joint sprains typically result from a volar-to-dorsal force, ulnarly or radially directed at the joint when it is in some degree of flexion, and these injuries are most frequently seen in individuals aged 30-39 years. Most partial ligament tears can be treated conservatively with a period of immobilization, but complete tears, chronic injuries, and those that fail to respond to conservative interventions typically require surgery. Although MP joint sprains are relatively uncommon, they do require an accurate diagnosis and prompt treatment to prevent the long-term loss of function.1-4

Pathophysiology

  • The mechanism of injury in MP joint sprains is usually a volar-to-dorsal force that is either radially- or ulnarly-directed while the joint is in some degree of flexion.5
  • If the collateral ligament ruptures, it typically tears from its insertion, while tears from the origin occur less frequently. In these cases there is typically an accompanying overlying transverse or oblique tear of the adjacent sagittal band of the extensor hood.6
  • MP joint sprains are less common than PIP joint sprains because the joint is well protected from extreme stress due to its proximal position within the web space.4

Related Anatomy7,8

  • Ulnar collateral ligament (UCL): proper and accessory
  • Radial collateral ligament (RCL): proper and accessory
  • Dorsal capsule
  • Volar plate
  • The MP joint is a synovial condyloid joint that allows circumduction and movements in the sagittal and coronal planes.1
  • The static stabilizers of the MP joint include the collateral ligament/volar plate complex and the pulley system, while the deep transverse metacarpal ligament and extensor hoods also reinforce the MP joint capsule. Intrinsic and extrinsic muscles and tendons serve as the dynamic stabilizers.1
    • The proper and accessory collateral ligaments are the primary soft tissue stabilizers of the MP joint, and together they form a reciprocal force couple that provides lateral stability and guides the joint throughout its range of flexion and extension.6
    • The proper collateral ligament of the MP joint inserts proximally into the posterior tubercle and adjacent pit on the side of the metacarpal heads.1
  • Ligamentous injuries of the MP joint are typically classified using the following system:
    • Grade 1: involves asymmetric swelling and tenderness over the collateral ligament without instability on the lateral stress test
    • Grade 2: involves complete disruption of the collateral ligament, but the volar plate remains intact. There is some instability, but stress testing reveals a definite soft tissue endpoint indicating that the collateral is not completely torn.
    • Grade 3: involves total collateral ligament disruption and volar plate rupture, with clinical examination depicting evidence of subluxation or dislocation on active extension9,10 Stress testing reveals no soft tissue endpoint indicating that the collateral is completely torn.

Incidence and Related Conditions

  • One study found that finger injuries accounted for 38% of 3.5 million upper extremity injuries in the U.S. About 16% of these injuries were sprains and strains, while dislocations only accounted for ~5%.11
  • The incidence of finger sprains is 37.3 per 100,000 person/years, and the PIP joint is the most commonly injured joint of the hand, followed by the thumb MP joint and MP joint of the fingers. Due to their infrequency, statistics are lacking on the specific occurrence rates of sprains to the distal interphalangeal (DIP) joint of the fingers and thumb interphalangeal (IP) joint.11
  • The collateral ligaments of the MP joints are damaged in approximately 1 out of every 1,000 hand injuries. Of these, 61% involve the thumb MP joint and 39% involve the MP joints of the fingers.12
  • Collateral ligament injuries of the finger MP joints are most common between the ages of 30-39 years and they affect men and women nearly equally. The incidence is highest in the long finger, where UCL and RCL injuries occur at similar frequencies.6 RCL injuries are more common in the ring and little fingers, while UCL injuries are more likely in the index finger.5
    • It has been proposed that the true frequency of MP joint injuries may be underestimated due to lack of clinical awareness and consequent missed diagnoses.2

Differential Diagnosis

  • Collateral ligament tear
  • Volar plate tear
  • Extensor tendon avulsion
  • MP joint dislocation
  • Proximal phalanx fracture
  • Metacarpal fracture
ICD-10 Codes

  • SPRAIN

    Diagnostic Guide Name

    SPRAIN

    ICD 10 Diagnosis, Single Code, Left Code, Right Code and Bilateral Code

    DIAGNOSISSINGLE CODE ONLYLEFTRIGHTBILATERAL (If Available)
    - WRIST    
     - CARPAL JOINT S63.512_S63.511_ 
     - RADIOCARPAL JOINT S63.522_S63.521_ 
     - OTHER SPECIFIED SPRAIN OF WRIST S63.592_S63.591_ 
    - METACARPOPHALANGEAL (MCP)    
     - INDEX S63.651_S63.650_ 
     - MIDDLE S63.653_S63.652_ 
     - RING S63.655_S63.654_ 
     - LITTLE S63.657_S63.656_ 
     - THUMB S63.642_S63.641_ 
    - INTERPHALANGEAL (DIP, PIP)    
     - INDEX S63.631_S63.630_ 
     - MIDDLE S63.633_S63.632_ 
     - RING S63.635_S63.634_ 
     - LITTLE S63.637_S63.636_ 
    - CARPOMETACARPAL OF THUMB (CMC) S63.8X2_S63.8X1_ 

    Instructions (ICD 10 CM 2020, U.S. Version)

    THE APPROPRIATE SEVENTH CHARACTER IS TO BE ADDED TO EACH CODE FROM CATEGORY S63
    A - Initial Encounter
    D - Subsequent Routine Healing
    S - Sequela

    ICD-10 Reference

    Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208

Symptoms
History of finger trauma with MP joint instability and/or deformity
Pain, swelling, and ecchymosis over the MP joint
Decreased finger motion and impaired grip
Typical History

A typical patient is a 35-year-old, right-handed woman who injured her hand in a snowboarding accident. The woman was riding downhill and navigating through a thick patch of trees when she lost her balance and could not avoid hitting an approaching tree. She placed her hand out to brace her for the impact, and the long finger of her left hand absorbed the brunt of the collision. The tree created an ulnarly-directed, volar-to-dorsal force on the MP joint of the long finger, which was slightly flexed, causing a sprain of its UCL. The woman experienced moderate pain right away and later noticed swelling and tenderness over the MP joint, leading her to sit out for the rest of the day.

Positive Tests, Exams or Signs
Work-up Options
Images (X-Ray, MRI, etc.)
MP Joint Imaging
  • Left long finger MP joint sprain with UCL avulsion fracture (arrow). Expect fracture to heal with scar not bone.
    Left long finger MP joint sprain with UCL avulsion fracture (arrow). Expect fracture to heal with scar not bone.
Treatment Options
Treatment Goals
  • Control pain and swelling
  • Maintain stability, motion and strength, i.e. maintain function
Conservative
  • The goal of injury management for MP joint sprains is to obtain a strong, stable, and pain-free joint with an optimum ROM.13
  • Treatment decisions should be based on the injury pattern, joint stability, and level of chronicity, but the majority of grade 1 MP joint sprains can be effectively managed conservatively with a period of immobilization.5 Grade 2 sprains in which the MP joint is stable can usually be treated conservatively, but those with marked instability and most grade 3 sprains require surgery.6
  • Grade 1 and stable Grade 2 sprains should be splinted in 30° of flexion for 3 weeks and reassessed.
  • Nonsteroidal anti-inflammatory drugs should only be used cautiously and for short period of time.9
  • Steroid injections may reduce pain and inflammation, but can be detrimental to healing. Most experts therefore caution against their use for acute MP joint sprains.9
Operative
  • Ligamentous MP joint injuries require surgical intervention when a ligament is completely ruptured, in chronic injuries with persistent pain and laxity after 12 weeks of conservative treatment and when joint instability manifests during the course of treatment, particularly in grade 2 injuries.6,9
  • Surgical options for the MP joint include primary repair, direct repair to bone with suture anchors or pullout sutures, and ligament reconstruction with autologous grafts.5Pullout or bone anchor sutures have been especially effective in achieving ligament repair at the origin or insertion of the ligament.6
  • Surgical repair of a MP joint collateral ligament is typically performed through a dorsolateral approach with opening of the extensor apparatus at the junction between the extensor tendon and sagittal band. 
    • Ligament fixation techniques include direct suture, minisuture anchor, and 1.5-mm screws, and the attachment should be performed with the MP joint at a minimum of 45° of flexion to set the correct tension.5
    • RCL injuries of the index finger are usually approached through a midaxial incision, while central digits may be approached dorsally. An intact sagittal band must be incised to expose the collateral ligament and any associated lesions.6
  • The re-establishment of RCL stability is particularly important for the MP joint of the index finger because of the considerable forces placed on the joint during pinch and grasp. A single transarticular K-wire may therefore be used at the surgeon’s discretion for tenuous repairs or in potentially noncompliant patients.6
  • After surgery, the finger should be immobilized in 30° flexion for ~3 weeks to avoid excessive tension, and an additional 2 weeks of buddy taping or splinting may also be needed. Hand therapy is typically initiated 4-6 weeks after surgery, and patients are generally able to return to work in 11 weeks with near normal MP joint ROM.5,15
CPT Codes for Treatment Options

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Common Procedure Name
MP joint contracture release
CPT Description
Capsulectomy or capsulotomy; metacarpophalangeal jonit, each joint
CPT Code Number
26520
Common Procedure Name
Ulnar collateral ligament repair
CPT Description
Repair of collateral ligament, metacarpophalangeal or interphalangeal joint
CPT Code Number
26540
Common Procedure Name
Gamekeeper's repair
CPT Description
Primary repair collateral ligament metacarpophalangeal joint
CPT Code Number
26542
CPT Code References

The American Medical Association (AMA) and Hand Surgery Resource, LLC have entered into a royalty free agreement which allows Hand Surgery Resource to provide our users with 75 commonly used hand surgery related CPT Codes for educational promises. For procedures associated with this Diagnostic Guide the CPT Codes are provided above. Reference materials for these codes is provided below. If the CPT Codes for the for the procedures associated with this Diagnostic Guide are not listed, then Hand Surgery Resource recommends using the references below to identify the proper CPT Codes.

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CPT 2021 Professional Edition: Spiralbound

Complications

Infection

  • Stiffness
  • MP flexion deformity 
  • Osteoarthritis
  • Swan neck deformity
  • MP joint contracture
  • Pseudo-boutonniere deformity
  • According to some authors, most complications associated with MP sprains are due to over-treatment—such as excessive immobilization—rather than the absence of treatment.14
  • Failure to initially repair a completely torn collateral ligament of the MP joint may result in chronic pain, instability, deformity, weakness, and/or osteoarthritis. Late ligament repair or reconstruction may be needed to resolve these cases.6
Outcomes
  • MP joint sprains typically have an excellent prognosis, and most patients will eventually regain full finger ROM; however, some patients will continue to experience pain, stiffness, and disability up to 3 months after the injury.1,6 The prognosis often depends of the promptness of treatment, as injuries managed early are typically associated with more positive outcomes.14
  • In general, most patients with acute complete ligament tears or unstable injuries report full or nearly full recovery of motion and strength within 12 weeks if they undergo surgery early.6
  • One study reported on 12 complete collateral ligament tears of the MP joints in 10 patients, most of which underwent surgical repair. Most patients regained full mobility within an average of 10 weeks, had no residual instability or pain, and remained asymptomatic at a 2-year follow-up.12
  • Another study reported satisfactory results following repair of complete collateral ligament tears of the MP joints in 10 patients.16
Key Educational Points
  • Many patients present several weeks or months after injury, at which point they still experience pain, swelling, and stiffness. This can lead some patients to protect the finger excessively, which results in additional stiffness and hinders their recovery.17
  • Patients, athletic trainers, and coaches often overlook MP joint injuries, and delayed or improper treatment often occurs as a result, which can lead to permanent deformities of the affected digit.10
  • Patient should be counseled that even with a stable MP joint, pain with maximal MP flexion and forceful gripping may continue for one year.
  • A complete RCL tear and instability of the index finger may have particularly devastating consequences if not diagnosed and repaired.6
  • MP joint stability - important to check for lateral instability of the MP joint in both the extended and flexed positions.4
  • Routine X-rays - some experts recommend taking radiographs before stress testing.6
  • Radiographic evaluation should include a Brewerton view to look for avulsed bone fragments.3
  • Lateral stress test - performed with the MP joint in full extension to test the integrity of the accessory collateral ligament.  Pain without laxity may indicate ligament attenuation or a grade 1 injury, while pain with laxity and an end point may indicate a grade 2 injury, and laxity and lack of an end point are indicative of a grade 3 injury.6
  • Ultrasound - has become increasingly effective at imaging the articular surface and associated soft tissues of the fingers, in part because it allows for dynamic evaluation.5  Collateral ligaments normally appear as thick fibrillar or echoic bands, while sprains appear as a diffusely swollen hypoechoic ligament with loss of normal ligament fibrous structure.1,9. Other findings for ligamentous injuries include frank ligament discontinuity or detachment, ligament thickening, and extracapsular leakage of joint fluid.5
  • MRI
    • For MP joint ligamentous injuries, MRI can confirm if a collateral ligament is damaged, but its sensitivity for distinguishing between partial and complete ruptures appears to be low. Patient history and the physical examination should therefore be relied upon more heavily for accurately diagnosing these injuries.2,6
References

New and Cited Articles

  1. Draghi, F, Gitto, S and Bianchi, S. Injuries to the Collateral Ligaments of the Metacarpophalangeal and Interphalangeal Joints: Sonographic Appearance. J Ultrasound Med 2018;37(9):2117-2133. PMID: 29480577
  2. Lutsky, K, Levi, D and Beredjiklian, P. Utility of MRI for diagnosing complete tears of the collateral ligaments of the metacarpophalangeal joints of the lesser digits. Hand (N Y) 2014;9(1):112-6. PMID: 24570647
  3. Peterson, JJ, Bancroft, LW, Kransdorf, MJ, et al. Evaluation of collateral ligament injuries of the metacarpophalangeal joints with magnetic resonance imaging and magnetic resonance arthrography. Curr Probl Diagn Radiol 2007;36(1):11-20. PMID: 17198888
  4. Ishizuki, M. Injury to collateral ligament of the metacarpophalangeal joint of a finger. J Hand Surg Am 1988;13(3):444-8. PMID: 3379287
  5. Prucz, RB and Friedrich, JB. Finger joint injuries. Clin Sports Med 2015;34(1):99-116. PMID: 25455398
  6. Lourie, GM, Gaston, RG and Freeland, AE. Collateral ligament injuries of the metacarpophalangeal joints of the fingers. Hand Clin 2006;22(3):357-64. PMID: 16843801
  7. Bowers, WH, Wolf, JW, Jr., Nehil, JL, et al. The proximal interphalangeal joint volar plate. I. An anatomical and biomechanical study. J Hand Surg Am 1980;5(1):79-88. PMID: 7365222
  8. Bowers, WH. The proximal interphalangeal joint volar plate. II: a clinical study of hyperextension injury. J Hand Surg Am 1981;6(1):77-81.PMID: 7204922
  9. Rozmaryn, LM. The Collateral Ligament of the Digits of the Hand: Anatomy, Physiology, Biomechanics, Injury, and Treatment. J Hand Surg Am 2017;42(11):904-915. PMID: 29101974
  10. Kamnerdnakta, S, Huetteman, HE and Chung, KC. Complications of Proximal Interphalangeal Joint Injuries: Prevention and Treatment. Hand Clin 2018;34(2):267-288. PMID: 29625645
  11. Ootes, D, Lambers, KT and Ring, DC. The epidemiology of upper extremity injuries presenting to the emergency department in the United States. Hand (N Y) 2012;7(1):18-22. PMID: 23449400
  12. Delaere, OP, Suttor, PM, Degolla, R, et al. Early surgical treatment for collateral ligament rupture of metacarpophalangeal joints of the fingers. J Hand Surg Am 2003;28(2):309-15. PMID: 12671864
  13. Joyce, KM, Joyce, CW, Conroy, F, et al. Proximal interphalangeal joint dislocations and treatment: an evolutionary process. Arch Plast Surg 2014;41(4):394-7. PMID: 25075363
  14. Adi, M, Hidalgo Diaz, JJ, Salazar Botero, S, et al. Results of conservative treatment of volar plate sprains of the proximal interphalangeal joint with and without avulsion fracture. Hand Surg Rehabil 2017;36(1):44-47.PMID: 28137442
  15. Carlo, J, Dell, PC, Matthias, R, et al. Collateral Ligament Reconstruction of the Proximal Interphalangeal Joint. J Hand Surg Am 2016;41(1):129-32. PMID: 26614593
  16. Schubiner, JM and Mass, DP. Operation for collateral ligament ruptures of the metacarpophalangeal joints of the fingers. J Bone Joint Surg Br 1989;71(3):388-9. PMID: 2722926
  17. Bot, AG, Bekkers, S, Herndon, JH, et al. Determinants of disability after proximal interphalangeal joint sprain or dislocation. Psychosomatics 2014;55(6):595-601. PMID: 25034813

Reviews

  1. Rozmaryn, LM. The Collateral Ligament of the Digits of the Hand: Anatomy, Physiology, Biomechanics, Injury, and Treatment. J Hand Surg Am 2017;42(11):904-915. PMID: 29101974
  2. Lourie, GM, Gaston, RG and Freeland, AE. Collateral ligament injuries of the metacarpophalangeal joints of the fingers. Hand Clin 2006;22(3):357-64. PMID: 16843801

Classics

  1. Robins RH. Injuries of the metacarpophalangeal joints. Hand1971;3(2):159-63. PMID: 5127924
  2. Wolfe, S. W., Hotchkiss, R. N., & Green, D. P. (2011). Greens operative hand surgery(6th ed., Vol. 1). Elsevier Churchill Livingstone.
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