Varus will have varus; a radiological study to assess and predict varus stem placement in uncemented femoral stems.

BACKGROUND: Varus inclination of the uncemented stem is not necessarily a technical error. The proximal femoral anatomy of hips with a coxa vara deformity frequently predisposes varus inclination. METHODS: We reviewed a series of 200 patients undergoing primary uncemented THA with the Corail® hip system. Preoperative data were based on patient demographics, diagnosis, and radiographic information (preoperative templating-CT measurements), and compared postoperative alignment for each stem and type of stem used. Proximal femoral traits which can alert surgeons, when templating preoperatively, to potential varus alignment were noted. RESULTS: All stems were inserted either in neutral or varus alignments. Low neck shaft angle is strongly predictive of increased varus stem alignment (p<0.001). Stems inserted with higher varus alignment were associated with the preoperative morphological traits associated with coxa vara hip deformities - increased femoral offset (p<0.001), greater trochanteric overhang (p<0.001), greater trochanteric height (p<0.046), and a lower canal flare index (p<0.046). CONCLUSIONS: Varus stem alignment is neither unexpected nor necessarily a technical failure when using this particular uncemented stem system. Coxa vara deformities, due to a combination of morphological traits, are more likely to be inserted with higher varus alignment than hips with normal or higher neck shaft angles. Surgeons need to be aware of this when carrying out preoperative templating and intraoperative assessment, in order to prevent over-compensation for offset, length or stability.

Total hip arthroplasty after contralateral hip disarticulation: a challenging "simple primary".

Patients with lower limb amputation have a high incidence of hip and knee osteoarthritis in both the residual limb and the contralateral limb. Hip disarticulation is a radical surgery usually performed in younger patients after malignancy or trauma. Compliance is poor with existing prostheses, resulting in increased dependency on and use of the remaining sound limb. We describe a case of a crutch-walking 51-year-old woman who presented with severe left hip arthritis 25 years after a right hip disarticulation, and was treated with total hip arthroplasty. Total hip arthroplasty without a contralateral hip joint is challenging. We discuss the complex technical considerations associated with the patient's arthroplasty, in particular the selection of prostheses and bearing surfaces, and the preoperative and intraoperative assessment of limb length and offset.