Ulnar Nerve Translocation Following a Routine Distal Radius Fracture.

A 35-year-old right hand dominant male sustained a high energy closed right distal radius fracture with associated generalized paresthesias. Following closed reduction, the patient was found to have an atypical low ulnar nerve palsy upon outpatient follow-up. After continued symptoms and an equivocal wrist MRI the patient underwent surgical exploration. Intraoperatively, the ulnar nerve as well as the ring and small finger flexor digitorum superficialis tendons were found to be translocated around the ulnar head. The nerve and tendons were reduced, the median nerve was decompressed, and the fracture was addressed with volar plating. Post-operatively, the patient continued to have sensory deficits and stiffness of the ring and small fingers. After one year, he reported substantial improvements as demonstrated by full sensation (4.0 mm two-point discrimination) and fixed flexion contractures at the proximal and distal interphalangeal joints of the small finger. The patient returned to work without functional limitations. This case highlights a unique case of ulnar nerve and flexor tendon entrapment following a distal radius fracture. History, physical examination, and a high index of clinical suspicion is essential for proper management of this rare injury. Level of Evidence: V.

Role of Dynamic Stabilizers of the Elbow in Radiocapitellar Joint Alignment: A Prospective In Vivo Study.

PURPOSE: To investigate the effect of dynamic stabilizers of the elbow on radiocapitellar joint alignment, before and after the administration of regional anesthesia. METHODS: At a single institution, 14 patients were prospectively enrolled in a study using a within-subjects control design. Before performing a supraclavicular regional block, 10 fluoroscopic images (1 anteroposterior and 9 lateral views) of the elbow were obtained for each patient. The lateral images were obtained with the forearm in maximal supination, neutral rotation, and maximal pronation, and these forearm positions were repeated for 3 elbow positions: (1) full extension; (2) flexion to 90°, with 0° of shoulder internal rotation; and (3) flexion to 90°, with 90° of shoulder internal rotation. After obtaining the 10 initial images, a block was performed to achieve less than 3/5 motor strength of the imaged extremity, followed by obtaining the same 10 images in each patient. Radiocapitellar ratio, defined as the minimal distance between the right bisector of the radial head and the center of the capitellum divided by the diameter of the capitellum, was measured in each image. RESULTS: The 14 patients had a mean age of 47.8 ± 15.7 years, and 10 (71.4%) patients were women. A difference between radiocapitellar ratios measured before and after the regional block administration was observed for all lateral images (-1.0% ± 7.2% to -2.2% ± 8.0%), although this difference was less than the minimum clinically important difference. CONCLUSIONS: Paralysis of the dynamic stabilizers of the elbow produces a difference in the radiocapitellar joint alignment, but this did not reach the minimum clinically important difference. CLINICAL RELEVANCE: Paralysis of the dynamic stabilizers of the elbow via a supraclavicular nerve block produces no clinically relevant effect on the radiocapitellar alignment of uninjured elbows.

Zone 2 Flexor Tendon Repair Location and Risk of Catching on the A2 Pulley.

PURPOSE: To determine the region of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons in zone 2 that, when involved by a laceration repair, will reliably catch on the A2 pulley after surgery. METHODS: Using fresh-frozen cadavers (5 hands, 20 digits), excursions of the FDP and FDS tendons were measured in relation to the A2 pulley. The C1, A3, and C2 pulleys were resected. The digit was maximally flexed by applying traction to the flexor tendon in the forearm. An 8-0 suture tag was placed in the flexor tendons immediately distal to the A2 pulley. The digit was then passively fully extended to measure tendon excursion. Measurements were repeated with 50% venting and 100% release of the A4 pulley. Reference points such as tendon insertions and flexion creases were obtained. This protocol was repeated sequentially for the index, middle, ring, and little fingers. RESULTS: For all 20 fingers, the suture placed into the FDP just distal to the A2 pulley with the finger fully flexed traveled 1.6 ± 1.9 mm distal to the proximal edge of the A4 pulley with passive extension of the finger. The mean excursion for the FDP was 24.6 ± 3.2 mm, and 16.9 ± 3.1 mm for the FDS. The mean A2 pulley length was 16.2 ± 3.5 mm, and the mean distance between the distal edge of the A2 pulley and the proximal edge of the A4 pulley was 23.0 ± 3.3 mm. Venting the A4 pulley 50% and 100% increased FDP excursion a maximum of 0.9 and 1.9 mm, respectively. CONCLUSIONS: An FDP repair proximal to the A4 pulley will slide under the A2 pulley with full active digital flexion after surgery. If the distal FDP stump lies underneath the A4 pulley with the digit fully extended, the FDP repair will not likely engage the A2 pulley with full flexion after surgery. The FDP excursion can be reliably predicted as a percentage of the A2 (distal) to the A4 (distal) pulley distance. Most importantly, the distance between the repair site and the A4 pulley approximately equals the length of the A2 pulley that requires release to avoid postoperative triggering. CLINICAL RELEVANCE: Knowledge of this high-risk region of flexor tendon repair will guide surgeons regarding the potential need for partial release of the A2 pulley.