Stem and osteotomy length are critical for success of the transfemoral approach and cementless stem revision

Abstract

Background: The transfemoral approach is an extensile surgical approach that is performed routinely to facilitate cement and implant removal and improve exposure for revision stem implantation. Previous studies have looked at clinical results of small patient groups. The factors associated with fixation failure of cementless revision stems when using this approach have not been examined.

Questions/purposes: We determined (1) the clinical results and (2) complications of the transfemoral approach and (3) factors associated with fixation failure of revision stems when using the transfemoral approach.

Patients and methods: We retrospectively examined all our patients in whom femoral stem revision was performed through a transfemoral approach between December 1998 and April 2004 and for whom a minimal followup of 2 years was available. One hundred patients were available for this study. The mean (± SD) postoperative followup was 5 years (± 1.64 years).

Results: The average Harris hip score improved from 45.2 (± 14.02) preoperatively to 83.4 (± 11.86) at final followup. Complete radiographic bony consolidation of the osteotomy site was observed in 95% of patients. Dislocations occurred in 9% of patients. Four revision stem fixation failures were observed, all occurring in patients with primary three-point fixation. Three-point fixation was associated with short osteotomy flaps and long revision stems.

Conclusions: The transfemoral approach is associated with a high rate of osteotomy flap bony healing and good clinical results. When using the transfemoral approach, a long osteotomy flap should be performed and the shortest possible revision stem should be implanted.

Level of evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Fig. 1A–B

(A) An AP radiograph shows a revision stem with press-fit anchoring in the diaphyseal zone. (B) The magnified image of the femur diaphysis shows a cross-sectional area of absolute bone-implant-bone contact in the femur isthmus between the black arrows.

Fig. 2A–B

(A) An AP radiograph shows a revision stem with three-point fixation. (B) The magnified image of the femur diaphysis shows the revision stem does not have a cross-sectional area of absolute bone-implant-bone contact in the femur isthmus. The black arrows show the region where the fins of the revision stem come in contact with bone; the white arrows show lack of implant-bone contact.

Fig. 3A–C

(A) In a curved femur, a short osteotomy flap leads to a three-point fixation when using a straight revision stem. In such cases, the distal extent of the osteotomy should be performed close to the femoral isthmus to allow a perfect conical preparation of the femoral isthmus. (B) A too-long fixation stretch in the femoral diaphysis also leads to three-point fixation when using a straight revision stem despite an adequate osteotomy flap length. (C) Press-fit fixation is achieved when the osteotomy flap is sufficiently long and when a short stem is used. The distal extent of the osteotomy is performed close to the femoral isthmus without damaging the isthmus. A bone-implant-bone contact zone height of 4 to 5 cm is sufficient for primary stability of the straight revision stem.