HandLab Clinical Pearls

September 2020 No. 64

Hands Down: Scapholunate Instability Treatment

Karol Young, OTD, OTR/L, CHT

 

A 73-year-old man [H.W.] presented in our clinic after twisting his right dominant wrist as he caught himself while falling. Diagnosed with a probable scapholunate [SL] ligament tear, H.W. could not undergo further diagnostic testing or surgery because of comorbidities.  H.W. complained of localized dorsoradial wrist pain [6/10], had a positive scaphoid shift test (1), mild dorsal wrist edema, a weak and painful grip [20 lbs. as compared to 60 lbs. on contralateral side], and right proximal forearm muscle wasting. [See Figure 1.] My co-worker asked, “How should we treat this patient?”

Figure 1. Wasting of the right proximal forearm muscles.

To reduce the persistent pain [6/10] H.W. had experienced for 2-3 months, he wore a wrist immobilization orthosis for two weeks. After two weeks of immobilization, his pain was reduced to 1/10, and he began a program of stabilization exercises to control his SL instability.

Stabilization exercises are based on kinesiological rationale. When SL instability is present, the pull of the extensor carpi ulnaris [ECU] causes scaphoid collapse.

This may seem illogical since the ECU tendon inserts on the base of the fifth metacarpal which is on the opposite side of the wrist. But the ECU pronates the distal carpal row, which pulls the scaphoid into flexion, pronation, and slight radial deviation.

The extensor carpi radialis longus [ECRL], extensor carpi radialis brevis [ECRB], and the abductor pollicis longus [APL] tendons on the other side of the wrist, supinate the distal carpal row which pulls the scaphoid into extension and supination: the normal anatomical position.

Volarly, the flexor carpi radialis [FCR] tendon lies over the scaphoid and when it contracts, the tension assists in scaphoid stabilization (2-4).

Therefore, in the presence of SL ligament insufficiency, the goal is to inhibit ECU activity [prevent distal row pronation] and activate ECRL, APL and FCR activity [encourage distal row supination] to maintain scaphoid stability, thus minimizing stress to the scapholunate ligament.

As H.W. began weaning from his orthosis he initiated active range of motion focusing on wrist flexion with ulnar deviation and wrist extension with radial deviation [called dart thrower’s motion]. [See Figure 2.] This exercise not only uses wrist motion required for activities of daily living, but also maximizes the biomechanical advantage of the ECRL and APL (4).

Figure 2. Dart thrower’s motion facilitates a functional movement pattern

Isometric exercises to activate the FCR, ECRL, and ECRB were begun to promote stability of the distal carpal row, with close monitoring to prevent pain exacerbation.  With his pain under control, the patient progressed to isotonic exercises with the forearm in pronation, to inhibit ECU activation. [See Figure 3.]

Figure 3: Isometric and isotonic activities in pronation inhibit use of the extensor carpi ulnaris

Because H. W. had not used his wrist in several months, sensorimotor activities including mirror feedback, closed chain exercises, and perturbation exercises were implemented to improve his joint position sense (4). Improving joint position sense helps avoid re-injury. [See Figure 4.]

Figure 4. Activities for improving wrist joint position sense

Current evidence of SL ligament biomechanics guided H.W.’s non-surgical treatment.  At the time of discharge, H.W. used his cane in his right hand, brushed his teeth, and drove without pain. His grip strength increased by 12 lbs. and his pain level remained 0/10 both at rest and with activity. As a precaution, he continued to use a wrist support while doing yard work and heavy lifting.

 

  1. Watson HK, Ashmead DIV, Makhlouf MV. Examination of the scaphoid. J Hand Surg. 1988;13: 675-660.
  2. Esplugas M, Garcia-Elias M, Lluch A, Pérez ML. Role of muscles in the stabilization of ligament-deficient wrists. J Hand Ther. 2016;29: 166-174
  3. Eraktas I, Ayhan C, Hayran M, Soylu AR. Alterations in forearm muscle activation patterns after scapholunate interosseous ligament injury: A dynamic electromyography study. J Hand Ther. 2020; xxx:1-11. https://doi.org/10.1016/j.jht.2020.03.018.
  4. Wolff AL, Wolfe SW. Rehabilitation for scapholunate injury: Application of scientific and clinical evidence to practice. J Hand Ther. 2016;29: 146-153.

 

Download Clinical Pearl No. 64, Hands Down: Scapholunate Instability Treatment, September 2020

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Disclaimer: BraceLab Clinical Pearls are intended to be an informal sharing of practical clinical ideas; not formal evidence-based conclusions of fact.

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