Lower limb frontal and sagittal plane alignment and joint orientation have significant consequences for function and wear on the hip, knee and ankle. There is a normal range for the orientation of these joints relative to the mechanical and anatomic axis of the femur and/or tibia. We can use the normal joint orientation to accurately plan realignment of a deformed femur or tibia. In the frontal plane we use both anatomic and mechanical axis lines for planning. In the sagittal plane, the mechanical axis has less relevance and, therefore, only the anatomic axis is used for planning.

Purpose Despite the fact that new and modern short-stems allow bone sparing and saving of soft-tissue and muscles, we still face the challenge of anatomically reconstructing the femoro-acetabular offset and leg length. Therefore a radiological and clinical analysis of a short-stem reconstruction of the femoro-acetabular offset and leg length was performed. Methods Using an antero-lateral approach, the optimys shortstem (Mathys Ltd, Bettlach, Switzerland) was implanted in 114 consecutive patients in combination with a cementless cup (Fitmore, Zimmer, Indiana, USA; vitamys RM Pressfit, Mathys Ltd, Bettlach, Switzerland). Pre-and postoperative Xrays were done in a standardized technique. In order to better analyse and compare X-ray data a special double coordinate system was developed for measuring femoral-and acetabular offset. Harris hip score was assessed before and six weeks after surgery. Visual analogue scale (VAS) satisfaction, leg length difference and the existence of gluteal muscle insufficiency were also examined. Results Postoperative femoral offset was significantly increased by a mean of 5.8 mm. At the same time cup implantation significantly decreased the acetabular offset by a mean of 3.7 mm, which resulted in an increased combined femoroacetabular offset of 2.1 mm. Postoperatively, 81.7 % of patients presented with equal leg length. The maximum discrepancy was 10 mm. Clinically, there were no signs of gluteal insufficiency. No luxation occurred during hospitalization. The Harris hip score improved from 47.3 before to 90.1 points already at six weeks after surgery while the mean VAS satisfaction was 9.1. Conclusion The analysis showed that loss of femoroacetabular offset can be reduced with an appropriate stem design. Consequently, a good reconstruction of anatomy and leg length can be achieved. In the early postoperative stage the clinical results are excellent.

ObjectiveOne-stage bilateral, muscle-preserving, calcar-guided implantation technique through the modified minimally invasive anterolateral approach in supine position.IndicationsBilateral primary/secondary osteoarthritis of the hip; bilateral femoral head necrosis; ASA I–III.ContraindicationsASA IV; severe osteoporosis, other factors jeopardizing stable anchorage of cementless, calcar-guided short-stem; infection.Surgical techniqueSupine position. Skin incision. Opening of fascia; blunt dissection, pushing gluteal muscles dorsally with the index finger. Capsulectomy. Individual osteotomy according to preoperative plan to determine short-stem position. Remove femoral head. Prepare acetabulum. Position cup. Femoral preparation with the curved opening awl. Spare greater trochanter and gluteal muscles. Insert trial rasps in ascending sizes with “round-the-corner” technique. Select offset version, then trial reposition with intraoperative radiograph and implantation of the definitive implant. Wound closure. Consultation with the anesthesiologist to confirm a stable patient. Same procedure on contralateral hip.Postoperative managementMobilization on day 1 with immediate full weight bearing. Remove wound drains and urinary catheter (only female patients) on day 2. Intensive protocol of physiotherapy and rehabilitation. Thrombosis prophylaxis. Rehabilitation from day 7.ResultsAlmost 500 patients have undergone surgery since 2010. First consecutive 54 patients (108 hips) prospectively evaluated. After 2 years, Harris Hip Score was 98.8; satisfaction on visual analogue scale was 9.9. Low peri- and postoperative complication rates; no implant revisions.ConclusionThe muscle-sparing approach and the special “round-the-corner” technique in one-stage bilateral procedure leads to rapid mobilization and rehabilitation with excellent early clinical results and high satisfaction rates.

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