Digital Collateral Ligament Injury



Digital Collateral Ligament Injury


Steven T. Lanier

Michael S. Gart



INTRODUCTION



  • Thumb metacarpophalangeal (MP) ulnar collateral ligament (UCL) (note: thumb radial collateral ligament [RCL] injuries are managed similarly and are far less common, thus they are not discussed separately in this chapter)



    • Mechanism of injury



      • Acute—radial-directed force on abducted thumb, for example, fall with ski pole in hand (Skier’s thumb)


      • Chronic—attritional weakening leading to rupture (Gamekeeper’s thumb)


    • Normal anatomy



      • Proper collateral ligament (CL)—originates on ulnar aspect of thumb metacarpal (MC) head and inserts onto volar aspect of proximal phalanx



        • Under tension when metacarpophalangeal (MP) joint in 30° of flexion


      • Accessory CL—originates on ulnar aspect of thumb MC head (volar to proper CL) and inserts onto volar plate



        • Under tension when MP in full extension


      • Adductor pollicis (AddP) inserts into thumb MP joint extensor mechanism dorsal (superficial) to the UCL


      • CLs important for MP joint stability—resist valgus stress and volar subluxation of proximal phalanx with respect to MC



        • Tear results in instability, pain, diminished grip and pinch strength, and eventual arthritis


        • Static MP stabilizers—proper and accessory CL, volar plate, dorsal capsule



          • ▲ Proper CL and dorsal capsule taught in 30° of flexion


          • ▲ Accessory CL and volar plate taught in extension


        • Dynamic stabilizers



          • ▲ Thumb extrinsics—extensor pollicis longus (EPL), extensor pollicis brevis (EPB), flexor pollicis longus (FPL)



          • ▲ Thumb intrinsics—abductor pollicis longus (APB), flexor pollicis brevis (FPB), AddP


    • Pathoanatomy



      • UCL usually torn from distal insertion onto the proximal phalanx


      • Stener lesion—distally ruptured UCL retracts proximally and around the AddP insertion onto the extensor mechanism and comes to lie superficial to adductor insertion, making spontaneous healing of the cut ligament ends impossible


    • Epidemiology



      • Incidence is 50 per 100 000


      • UCL 9× more common than RCL injury


      • 60% to 90% of complete UCL tears associated with Stener lesion


    • Evaluation



      • History



        • History of fall onto abducted thumb or other traumatic injury


        • Acute injuries—pain, swelling, and ecchymosis over ulnar aspect of thumb MP joint


        • Chronic injuries—instability and resultant weakness of pinch or grip will be more prominent in chronic injuries


      • Physical examination



        • Swelling and ecchymosis over ulnar aspect of thumb MP joint


        • Pain with palpation over site of UCL avulsion, usually at the proximal phalanx insertion


        • Palpable nodule on ulnar aspect of thumb MC neck/head may represent a Stener lesion


        • Chronic UCL injuries may present with a supination deformity of the proximal phalanx


        • Check joint range of motion (ROM)


        • Obtain imaging before stress testing



          • ▲ Valgus testing contraindicated with thumb MP or proximal phalanx shaft fracture


        • Valgus stress testing



          • ▲ May require block of joint with local anesthesia to overcome guarding because of pain


          • ▲ Grasp thumb MC neck with one hand and control proximal phalanx rotation with the other hand


          • ▲ Test thumb against valgus stress in both full extension (accessory CL) and in 30° of flexion (proper CL)


          • ▲ Normal valgus laxity—6° in extension and 12° in flexion


          • ▲ Examination findings diagnostic of complete UCL tear:




            • image No definitive endpoint to mobility under stress


            • image Greater than 30° of mobility


            • image Greater than 15° difference in mobility from uninjured side


            • image If examination is unclear, can perform under fluorography or obtain stress radiographs


          • ▲ Instability in flexion alone—proper collateral ligament tear


          • ▲ Instability in both flexion and extension—proper and accessory collateral ligament tears


      • Imaging



        • X-ray (XR) series of thumb



          • ▲ Assess for avulsion fracture at site of UCL insertion onto proximal phalanx, present in 40%



            • image Two patterns—avulsion fracture with or without UCL injury


            • image If avulsion fracture associated with UCL injury will displace further with valgus stress


          • ▲ Assess for MP joint subluxation with radial and volar translation of the proximal phalanx


          • ▲ Osteoarthritis (OA) may be present in chronic injuries


        • Ultrasound or MRI can diagnose UCL tear and evaluate for Stener lesion if equivocal examination findings



          • ▲ US—sensitivity 76%, specificity 81%, positive predictive value 74%, negative predictive value 87%


          • ▲ MRI—sensitivity and specificity approach 100%


    • Classification



      • Grade I—partial UCL tear, no laxity with stress testing


      • Grade II—partial UCL tear, laxity but firm endpoint to stress testing


      • Grade III—complete UCL tear, laxity and no endpoint with stress testing


    • Acute management



      • Thumb immobilization with spica splint


      • Nonsteroidal anti-inflammatory drugs for pain relief


    • Definitive treatment



      • Nonoperative treatment—Grade I, II, or III without Stener lesion (protocol can be varied by severity of sprain vs partial tear)



        • Weeks 0 to 4—full-time immobilization in thumb spica splint


        • Weeks 4 to 6—therapy working on flexion and extension without valgus stress to joint; immobilization for high-risk activities



        • Weeks 6 to 8—begin grip strengthening


        • Week 12—return to full activities


      • Surgical indications—Grade III with Stener lesion; continued pain and instability following nonoperative management of Grade III injury



        • Contraindications—chronic UCL injuries with thumb MP arthritis are better treated with MP arthrodesis


      • Surgical approach

May 7, 2019 | Posted by in ORTHOPEDIC | Comments Off on Digital Collateral Ligament Injury
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