Double Pelvic Osteotomy for Hip Dysplasia

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Double Pelvic Osteotomy for Hip Dysplasia

Matthew D. Barnhart

The triple pelvic osteotomy (TPO) was first described as a surgical treatment for juvenile canine hip dysplasia in 1969, and its efficacy has been well proven in numerous publications since. The original stair‐step osteotomy procedure has undergone a number of iterations over time to ultimately become the current technique that involves pubic, ischial, and ilial osteotomies stabilized by a dedicated TPO plate and an ischial interfragmentary wire. While this TPO is effective at producing acetabular ventroversion and thereby reducing hip subluxation by improving femoral head coverage and articular surface contact, it has reported complication rates of 35–70% [13].

Screw loosening is the most common TPO complication, with reported rates of 30–62.5%, which is likely due to a combination factors including the low density of juvenile bone, minimal load sharing between osteotomy ends, and the high amount of motion generated at the ilial osteotomy site [25]. While screw loosening can be an incidental finding on routine postoperative radiographs, the potential for catastrophic loss of internal fixation and need for additional surgery is a real concern. Contradictory information exists regarding whether principles aimed at preventing screw loosening, including the use of cancellous screws, trans‐sacral screw placement and ischial wiring, offer any benefit at all [2]. Other reported remedies for screw loosening include retightening of screws via open or fluoroscopic assisted approaches, ilial hemicerclage wire placement, and application of a ventral ilial plate [6, 7]. Clearly, any technique or implant that could reduce or prevent screw loosening would be very valuable in this application.

Arguably, there are few other veterinary surgical techniques that have been as positively impacted and improved by the introduction of locking implants as has the TPO. The use of locking TPO plates has dramatically reduced the reported overall complications rates to 5–7% and nearly eliminated screws loosening as a complication [8, 9]. Between two reports in which 371 screws were used in pre‐angled seven‐hole locking TPO plates (New Generation Devices, Glen Rock NJ), only a single loosened screw was documented (Rose). Noteworthy is that a combination of locking and nonlocking screws was used in the cases. The lack of loosening of the nonlocking screws can likely be attributed to the single beam construct formed by the locking components, which eliminates motion between the plate, screws, and bone. An in vitro report also found that screw loosening was significantly reduced by the use of locking TPO plates [10]. Perhaps as importantly, locking TPO plates have truly made the double pelvic osteotomy (DPO) a viable alternative with distinct advantages over its predecessor.

In 2006, P.H. Haudiquet and J.F. Guillon presented the results from an in vitro study evaluating the feasibility of achieving sufficient acetabular ventroversion when only the ilium and pubic bones are osteotomized [11] (Figure 21.1). The goal of sparing the ischium was to simplify the TPO and maintain a more biomechanically stable construct that could reduce postoperative complications and morbidity. Segmental rotation was in fact possible because the intact ischium deformed through bending of the open pubic symphysis. Ironically, this same “soft plastic” juvenile bone, which is necessary to achieve rotation, is also what contributes to the aforementioned screw‐loosening complications.

Image described by caption.

Figure 21.1 (a, b) Approximately six‐week postoperative double pelvic osteotomy (DPO) and triple pelvic osteotomy (TPO) radiographs. Note lack of a ischial osteotomy and hemicerclage wire with the DPO.

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Jun 13, 2021 | Posted by in SUGERY, ORTHOPEDICS & ANESTHESIA | Comments Off on Double Pelvic Osteotomy for Hip Dysplasia

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