Unfortunately, there's a pay wall and the full text is not available. So I don't know if my biggest immediate question is addressed: if MMN causes weakness and disability because of motor nerve impairment, how does replacing tendons fix anything?
Second question: it sounds like there was some physical therapy involved. Might this have caused the improvement in strength rather than the surgery?
I realize this is just a single instance. If anyone knows of any similar cases of tendon replacement, I'm all ears.
Multifocal motor neuropathy is a progressive motor nerve disorder characterized by muscle weakness in the extremities. Muscle imbalance and weakness can become so severe that the involved extremity can be rendered nonfunctional. The purpose of this case report is to describe the physical therapy postoperative management of a patient who underwent a multiple tendon transfer to correct the loss of digital/wrist extension of the right upper extremity.
A 38-year-old woman with a medical diagnosis of multifocal motor neuropathy, which caused muscle imbalance and weakness in the right hand, underwent a multiple tendon transfer to correct the loss of digit and wrist extension. The pronator teres was transferred and attached to the extensor carpi radialis longus and brevis. The palmaris longus was transferred and attached to the extensor pollicis longus. The flexor carpi radialis was transferred and attached to the extensor digitorum communis. The patient underwent static and dynamic splinting and a modified tendon transfer protocol starting at 3 weeks and ending at 16 weeks postsurgery. The patient attended therapy 1 to 3 times a week, depending on protocol stage and need for skilled therapy intervention.
Patient-reported outcome measures included the Disabilities of the Arm, Shoulder and Hand (DASH) survey to monitor the return of function and the numeric pain-rating scale to assess pain. At the initial evaluation (3 weeks postsurgery), the patient's DASH score was 87.5 and her pain score was 7/10. At discharge (16 weeks postsurgery), the patient's DASH score was 37.5 and her pain score was 0/10. Strength impairment was monitored with hydraulic hand dynamometers and manual muscle testing. At discharge, her hand grip strength was 4.5 kg, her key pinch strength was 4.1 kg, and her 3-jaw pinch strength was 2.3 kg. Manual muscle testing grades were 5/5 for elbow extension/flexion, 4/5 for forearm pronation/supination, 2/5 for wrist extension, 1/5 for wrist radial deviation, 4−/5 for wrist ulnar deviation, 3/5 for extension from digits 2 through 4, 3+/5 for thumb extension, 5/5 for wrist flexion, and 5/5 for flexion from digits 1 through 5. At 1 year postsurgery, the DASH survey was sent to the patient for completion, at which time she reported a DASH score of 24.17.
This case demonstrated good outcomes for a patient who underwent a multiple tendon transfer to correct digital/wrist extension loss caused by multifocal motor neuropathy. This report provides guidance on the postoperative management of a fairly rare neurological disorder with an established orthopaedic surgery.