Abstract
BackgroundShort stems have become more and more popular for cementless total hip arthroplasty in the past few years. While conventional, uncemented straight stems for primary total hip arthroplasty (THA) have shown high survival rates in the long term, it is not known whether uncemented short stems represent a reasonable alternative. As cortical hypertrophy has been reported for short stems, the aim of this study was to determine the radiographic prevalence of cortical hypertrophy and to assess the clinical outcome of a frequently used short, curved hip stem.MethodsWe retrospectively studied the clinical and radiographic results of our first 100 consecutive THAs (97 patients) using the Fitmore® hip stem. Mean age at the time of index arthroplasty was 59 years (range, 19 – 79 years). Clinical outcome and radiographic results were assessed with a minimum follow-up of 2 years, and Kaplan-Meier survivorship analysis was used to estimate survival for different endpoints.ResultsAfter a mean follow-up of 3.3 years (range, 2.0 – 4.4 years), two patients (two hips) had died, and three patients (four hips) were lost to follow-up. Kaplan-Meier analysis estimated a survival rate of 100 % at 3.8 years, with revision for any reason as the endpoint. No femoral component showed radiographic signs of loosening. No osteolysis was detected. Cortical hypertrophy was found in 50 hips (63 %), predominantly in Gruen zone 3 and 5. In the cortical hypertrophy group, two patients (two hips; 4 %) reported some thigh pain in combination with pain over the greater trochanter region during physical exercise (UCLA Score 6 and 7). There was no significant difference concerning the clinical outcome between the cortical hypertrophy and no cortical hypertrophy group.ConclusionsThe survival rate and both clinical and the radiographic outcome confirm the encouraging results for short, curved uncemented stems. Postoperative radiographs frequently displayed cortical hypertrophy but it had no significant effect on the clinical outcome in the early follow-up. Further clinical and radiographic follow-up is necessary to detect possible adverse, long-term, clinical effects of cortical hypertrophy.
Highlights
Short stems have become more and more popular for cementless total hip arthroplasty in the past few years
Cortical hypertrophy was found in 50 hips (63 % of the 79 hips with radiological review), predominantly in Gruen zone 3 and 5 (Fig. 8)
There was no significant difference in postoperative UCLA, Tegner, and McMaster Universities Osteoarthritis index questionnaire (WOMAC) scores between the cortical hypertrophy and no cortical hypertrophy groups
Summary
Short stems have become more and more popular for cementless total hip arthroplasty in the past few years. Uncemented, straight titanium stems are widely used for total hip arthroplasty (THA) and have shown good to excellent long-term survival rates [1,2,3,4,5,6,7] Based on their design, there are accepted disadvantages of conventional straight stems, such as proximal stress shielding and loss of bone stock, risk of fracture of the greater trochanter, and a challenging implantation procedure by using a minimally invasive approach [8]. Gustke [14] published an experience report of 500 Fitmore® hip stems, with a mean follow-up of 1.3 years He reported a survival rate of 99.4 % with femoral revision for any reason as the endpoint and about 29 % cortical hypertrophy of his first 100 cases. The radiological finding of cortical hypertrophy has been shown in the past to possibly compromise clinical outcome at both short- and long-term follow-up
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