The survivorship and factors affecting the outcome of the use of spring plates in multifragmentary posterior wall acetabular fractures at a single academic institution.

Background: Multifragmentary posterior wall fractures are not uncommon after posterior hip fracture-dislocation. They can be elementary but are commonly associated with transverse acetabular fractures. Specific technical challenges are encountered when managing these fracture patterns. The loss of the posterior landmarks due to the associated comminution may render achieving an anatomical reduction and stable fixation difficult. The application of spring plates can provide a good buttress with multiple anchor points and creates a new cortex for the bridging plate.

Purpose Of The Study: -To assess the outcome and survivorship of the use of spring plates for the fixation of multi-fragmentary posterior wall fractures. -To analyse the factors affecting the outcome of the fixation of these challenging injuries.

Patients And Methods: We retrospectively reviewed all the patients who underwent posterior wall acetabular fixation using a spring plate between December 2009 and March 2020 at our institution. Forty-seven patients had a minimum follow-up of 1 year and were included in the study with a mean age of 36 ± 10 years (range:17-60) and a mean follow-up period of 4.4 ± 3.5 years. Seventeen patients had an associated transverse acetabular fracture, and an anterior columnar screw was used for additional fixation. Functional outcome was assessed using the Oxford hip score (OHS). Radiological assessment was undertaken for the images done immediately post-operatively and at the last follow-up. Patients with advanced post-traumatic arthritis and complications such as avascular necrosis (AVN), nerve injuries, non-union, heterotopic ossification and fixation failure were identified. The hazard rate of re-operation on the native hip was estimated using the life tables. Kaplan Meier analysis was used to assess survival with THR or excision arthroplasty as an endpoint.

Results: Six patients underwent a total hip replacement: secondary to AVN in four and infection in two patients. The hazard of THR was estimated at 6% (SE = 0.02) during the first three years, then decreased dramatically afterwards. The five-year survival of native hip was 83% (SE = 0.06). Native hip was expected to survive for 10.67 years (95% CI 9.49-11.83) without joint replacement. The mean OHS in our cohort was 33.66 (3-48), and 29 patients (61.70%) had an OHS of more than 30.

Conclusion: The use of spring plates to fix multifragmentary posterior wall fractures has excellent mid-term results, high survivorship and a low complication rate. Combining an anterior columnar screw and a posterior spring plate has shown to be a suitable fixation construct in selected patients with associated transverse acetabular fractures. A longer-term follow-up with a larger cohort using this fixation construct is needed.