Choice of surgical approach influences the combined anteversion needed for a stable and impingement-free total hip arthroplasty.

BACKGROUND: Accurate component positioning is the key for successful outcome after total hip arthroplasty (THA). Positioning acetabular and femoral components in a safe zone of 25°-50° on the basis of combined anteversion (CA) has shown to reduce instability and impingement. This safe zone was described for THAs performed through the posterior approach and has not been validated for other surgical approaches. METHODS: Seventy patients who underwent unilateral uncemented THA were included in the study; 35 patients-using posterior approach and the remaining 35-using trans-gluteal approach. All patients included had a stable and impingement-free THA at a mean follow-up of 39.2 ± 9.5 months. CT scan was performed to assess component positioning by calculating CA. The values were compared between the two groups to study possible differences. RESULTS: CA in the trans-gluteal group was significantly lower (32° ± 3.7° vs 38.4° ± 4.6°, P < .001) compared to posterior group. The difference in CA was due to the differences in acetabular anteversion, which was significantly low in the trans-gluteal group than the posterior group (22.1° ± 3.6° vs 27.8° ± 4.2°, P < .001). The mean femoral anteversion was similar in both groups. All trans-gluteal hips fell within the safe zone of 20°-40°, and all posterior hips fell within the safe zone of 25°-50°. CONCLUSION: A safe zone of 25°-50° is valid for THAs performed from the posterior approach but not universally applicable. For trans-gluteal approach, a safe zone of 20°-40° is better to provide a stable and impingement-free THA. CA varies with the surgical approach. THAs performed through the trans-gluteal approach can be stable and impingement-free with lesser CA compared to THAs performed through the posterior approach.

Volar hook plate stabilization of volar marginal fragments in intra-articular distal radius fractures.

BACKGROUND: In the setting of intra-articular distal radius fractures, the volar lunate facet (VLF) is the only articular segment that resists volar carpal subluxation. So, it is important to achieve a stable fixation of this key fragment. The VLF, when small (also called as volar marginal fragment, VMF) is located distal to the watershed line making fixation with the conventional volar locking plates difficult or impossible. METHODS: 18 patients with either an AO: 2R3B3 or a C3 fracture consisting of a VMF underwent surgical repair through a volar approach. The VMF was stabilised using a anatomical volar hook plate. Remaining fracture components were stabilised using 2.4/ 2.0 mm locked plates. Fracture healing, ability of the hook plate to maintain reduction of the VMF and complications were assessed during follow up. Functional outcome was evaluated using Mayo score and patient rated wrist evaluation questionnaires. RESULTS: All fractures united at follow up. Reduction of the VMF was maintained through healing with a stable radiocarpal and distal radioulnar joint. The mean flexion - extension wrist arc was 105° ± 10.2° The mean grip strength reached 74.6 ± 6% of the opposite side. The mean Mayo wrist score was 75 ± 5.3 and the mean patient rated wrist evaluation (PRWE) score was 15.2 ± 4.3 indicating recovery of wrist function. CONCLUSION: It is important to identify VMFs in intra-articular distal radius fractures. Anatomically designed volar hook plate achieves excellent low-profile stable fixation of this key fragment to allow early mobilisation without fearing loss of reduction and volar carpal subluxation.