Introduction and Aims: Currently, multiple femoral component types and sizes exist for primary total hip arthroplasty. However, component sizes for small femoral geometry are generally not available. The purpose of this study is to present the short-term use of a femoral component with sizes that extend into small femoral morphometry applications.

Method: Between November 2001 and December 2003, 20 primary THA cases and three revision THA cases were performed utilising a non-cemented, dual threaded, cone shaped (DTCS) modular femoral component manufactured in off-the-shelf sizes, which include those sizes for small femora. The components are made of CoCr and include a size ‘Z’ (19mm proximal, 9mm distal) and a size ‘Y’ (17mm proximal, 8mm distal). Both components have hydroxyapatite coating for stimulating increased bone on-growth and a modular neck allowing intra-operative adjustments of leg length, version, offset and neck length.

Results: The average patient follow-up was 10 months (range 64 days to 27 months). There were 19 (83%) hips in which the ‘Z’ component was used, and four (17%) hips with the ‘Y’ component. Radiographic evaluation revealed well-fixed and positioned components with evidence of bone densing in areas in intimate contact with the DTCS component. Radiographic evidence of minor stress shielding was observed in the greater trochanter (Gruen Zone 1) and the proximal calcar/neck cut region (Gruen Zone 7). Two revision cases (8%) required the additional use of a 6cm modular extension component (MEC) to bridge a proximal femoral deficiency. Two cases (8%) required adjunctive strut allografting at the time of surgery to protect a thin or deficient femoral cortex. There were no reported postoperative complications related to the femoral component. There was no disassociation of the modular neck from the femoral stem and there was no incidence of femoral component fracture.

Conclusion: While expanding component profile offerings into larger sizes is common, developing similar component designs for abnormally small femora is uncommon, beyond the scope of the materials used and only done as a ‘custom’ order. The DTCS modular femoral component used affords a versatile option when presented with cases involving small femoral morphometry. We conclude that the DTCS component in smaller sizes is promising and warranted for continued use.

Introduction and Aims: The incidence and technical complexity of revision total hip arthroplasty (THA) has and will continue to increase dramatically. We report the results of revision THA using a non-cemented, dual threaded, cone shaped, (DTCS) modular femoral component.

Method: Between June of 1999 and July of 2003, 41 revision THAs using a DTCS modular femoral component. Fifty-four percent of the patients were male and 46% were female with an average weight of 84kg (std dev: 30kg, range 57–60 kg), an average height of 170cm (sdt dev: 9cm, range: 155–182 cm) and an average body mass index (BMI) of 26 (std dev: 4, range: 18–31). The average patient age was 71 years (std dev: 12 years, range: 39–85 years).

Results: The average patient follow-up was 16 months (range 6–49 months). The average Harris hip score (HHS) at the most recent time to follow-up was 76. Broken into the HHS component parts, the average pain score was 40 of a possible 44, average motion was nine of a possible nine, and average function was 28 of a possible 47. Radiographic evaluation revealed wellfixed and positioned components with evidence of bone densing in areas in intimate contact with the DTCS component. Radiographic evidence of minor stress shielding was observed in the greater trochanter (Gruen Zone 1) and the proximal calcar/neck cut region (Gruen Zone 7). Post-operative complications included recurrent infection in four (10%), subsequently resolved with IV antibiotics; dislocation in three (7%), successfully treated by closed reduction and protective bracing; aseptic loosening in one (2%), with femoral component revision to a larger size; intra-operative periprosthetic fracture in one (2%), treated with ORIF (bone, plate and screws); and a non-union of a pre-revision fracture with subsequent component loosening in one (2%). Regardless of the degree of femoral deficiency, there was no incidence of component disassociation or component fracture.

Conclusion: Revision THA is a demanding undertaking and involves multivariate technical challenges that may include mechanical and material considerations such as prosthetic loosening, prosthetic and periprosthetic fracture. We show that the use of a DTCS modular femoral component affords the surgeon results equal to those reported for revision THA and allows intra-operative versatility independent of bone quality.