The importance of pronator quadratus repair in the treatment of distal radius fractures with volar plating

Abstract

Background Open reduction internal fixation (ORIF) of distal radius fractures via a volar approach involves surgical release of the overlying pronator quadratus (PQ) muscle. Complete repair of the PQ, defined as full and stable replacement of the periphery of the PQ back to its original anatomic location, is not always possible upon conclusion of the operation. Postoperative consequences of incomplete PQ repair with regards to range of motion (ROM), grip strength, and complications are not well documented. It was hypothesized that the completeness of PQ repair would yield no significant difference in the postoperative ROM, grip strength, and incidence of complications. Methods A retrospective review was performed of 110 repairs of distal radius fractures with ORIF via placement of a volar locking plate. The following clinical data were extracted: complete or incomplete PQ repair, patient age, gender, follow-up ROM/grip strength, and incidence of postoperative complications. Results and conclusions No significant difference in ROM, grip strength, and postoperative complications was detected between the complete and incomplete PQ repair groups. Complications consisted of two incidences of malunion requiring revision surgery and one occurrence of complex regional pain syndrome. There were no tendon ruptures. No statistical difference in ROM/grip strength or incidence of postoperative complications was detected between the complete and incomplete PQ repair groups. Regardless of the level of injury sustained by the PQ, surgeons should make an effort to cover the distal aspect of the volar plate during closure following distal radius fracture ORIF. Coverage of the distal aspect of the plate with the PQ (at a minimum) provides adequate results in ROM and grip strength, as well as protection against flexor tendon injury. Level of evidence Therapeutic Level III: Retrospective Comparative Study.

Sonographic Quantification of Pronator Quadratus Activity During Gripping Effort

“…Changes in the forearm position change kinetics and muscle activities, which largely determine the strength and stamina of power grips 5 , 21 , 35 . In accord with previous studies, 25 , 36 , 37 the average grip strength in the healthy adults in this study was greatest at the neutral position.…”

“…On the contrary, biomechanical studies 3 , 4 suggested that the pronator quadratus acts as a crucial distal radioulnar stabilizer rather than a prime agonist for forearm pronation, which indicates that the pronator quadratus is an important contributor to forceful gripping effort 2 . In fact, several clinical studies 5 – 7 reported that the volar approach through detachment of the pronator quadratus or the degree of pronator quadratus injury did not affect pronation and grip strength. This conflicting information has led to the disparity related to the true function of the pronator quadratus muscles involved in gripping and forearm rotation 2 .…”

Distal radial fractures

“…19 Tosti and Ilyas 20 prospectively assigned 60 patients to repair or no repair, and found no improvement in postoperative range of motion, grip strength, reoperation rate, DASH score, or visual analog scale (VAS) score at 1 yr. Reapproximation of the PQ during closure is controversial.…”

Interpretations of the Term “Watershed Line” Used as Reference for Volar Plating

“…Two retrospective studies and one prospective study analyzed the outcome after volar plating for distal radius fractures. 17,32,39 Four clinical studies directly analyzed the relation between volar plates and flexor tendons. 11,33,46 Four publications were expert opinions on the anatomy of the distal radius or volar plating of distal radius fractures.…”

“…In general, after comparing all descriptions, "the watershed line" could be divided into the following categories: (1) interpretations that are based on soft tissue landmarks 22,[30][31][32][33] and (2) interpretations using bony landmarks as the main anatomic reference. 11,17,[19][20][21]23,24,[26][27][28][34][35][36][37][38][39][40][41] Within these two categories, we found eight different interpretations of the term "watershed line."…”