Volar locking plate fixation is now the most common surgical treatment of distal radius fractures. This approach typically involves incision of the pronator quadratus (PQ) muscle, and whether it’s necessary to repair the PQ after fixation is controversial.
Surgeons in the Department of Orthopaedic Surgery at Brigham and Women’s Hospital recently reviewed the evidence for and against PQ repair. Dafang Zhang, MD, Maximilian A. Meyer, MD, Brandon E. Earp, MD, and Philip Blazar, MD, published their findings in the Journal of the American Academy of Orthopaedic Surgeons and say how it has influenced their practice.
The PQ has a role in the dynamic stabilization of the distal radioulnar joint and contributes to forearm pronation. Therefore, some authors advocate for PQ repair as a way to maximize postoperative function. Others believe PQ-splitting or PQ-sparing approaches are needed to minimize trauma to the PQ and preserve its function.
The case for PQ repair—Studies of PQ repair have demonstrated early postoperative improvements in pain, range of motion, and strength compared with no repair. This evidence comes from a retrospective study, a randomized study, and a meta-analysis of 11 randomized, nonrandomized and case–control studies.
The case against PQ repair—In theory, an unrepaired PQ will not destabilize the distal radioulnar joint because the deep head of the PQ attaches along the ulnar border of the distal radius and is generally not detached during volar locking plate fixation.
In a nonrandomized prospective trial, there were no differences between repair and no-repair treatment arms in function or pain at most time points through one year of follow-up. Results were similar in a randomized trial, and the unrepaired group had higher pronation strength.
Preventing Flexor Tendon Irritation
Aside from potentially restoring function, PQ repair might provide a biological barrier between the volar locking plate and the flexor tendons, minimizing the risk of tendon irritation. Previous research has clearly associated flexor tendon rupture, a devastating complication, with volar plate prominence.
The case for PQ repair—In a six-month trial in the European Journal of Orthopaedic Surgery & Traumatology, 65 patients received implants that were Soong grade 0 (did not extend volar to the most volar extent of the volar rim of the distal radius). The patients were randomized to PQ repair or no PQ repair. At all postoperative time points studied, the sonographic distance between the flexor pollicis longus (FPL) tendon and the volar rim was higher in the PQ repair group. This supports the idea that an intact PQ may serve as an effective biologic buffer.
The case against PQ repair—A retrospective study of 509 patients, which had an average 3.7-year follow-up, found PQ repair was not associated with implant removal, revision surgery for flexor tendon pathology, or other need for revision. In the Goorens trial, there was no case of direct contact between the FPL tendon and the volar rim in either treatment group, calling into question the importance of PQ repair with ideally positioned implants.
The Authors’ Practice
The authors have drawn separate conclusions about the importance of PQ repair:
Function—The preponderance of high-level evidence demonstrates no long term benefit of PQ repair for pain relief, range of motion, strength, or function.
Preventing tendon irritation—Current evidence neither conclusively supports nor refutes PQ repair for this purpose. PQ repair seems to increase the distance between the FPL tendon and the bone and plate, but it’s unclear whether this translates to fewer cases of tendon pathology.
Considering the limited evidence, the authors repair the distal edge of the PQ over the volar locking plate, not as an anatomic reconstruction but to serve as a biological buffer between the FPL tendon and the implant.