Abstract
Objectives: Assessment of the need for bolt removal in long stem distally interlocked revision stems.
Introduction: Proximal stress shielding might prove in the long run detrimental to the success of distally fixed revision stems. In our department during the last 4 years a proximally fixed stem combined with distal interlocking has been used. The manufacturer recommends bolt removal 18 months after surgery. The current investigation was conducted in order to assess the need for bolt removal.
Methods: 22 consecutive stems inserted from 1997 to the present were included. In all these cases femoral bone loss was graded according to Paprosky. A locked long stem is indicated in bony deficiencies of Grade 2B, 2C or 3 (i.e. loss of at least the metaphysis shell with or without major diaphyseal bone loss). Volkmann’s trans-femoral approach was used in 19 cases and sliding trochanteric osteotomy in the rest. Impaction grafting or structural allografts were not used to stabilize the prosthesis. In all cases grade II fixation (according to D’Antonio) was achieved at the end of the procedure.
Results: Median follow-up is 14 months. There were no septic complications. In two cases bolts slippage allowed prosthesis subsidence. One stem had to be revised due to aseptic failure. During surgery the prosthesis was markedly smaller than the regenerated medullary canal, and proximal bony fixation was not achieved. One patient’s bolts broke and in another case screw migration into soft tissue occurred. All patients attained ambulatory status. In none of the patients were the screws removed.
Discussion: Our results seem not to support the manufacturer’s recommendation for elective screw removal. Osteotomy healing appears to occur in all cases, however, time to healing varies greatly. The range of complete healing is from 3 months to 24 months. It does not appear that bolt retention leads to an interference with bone healing and bone regeneration of the proximal femur at the osteotomy site. Bolt breakage is rare and does not appear to adversely affect the results at least in the short term.
The abstracts were prepared by Orah Naor. Correspondence should be addressed to him at the Israel Orthopaedic Association, PO Box 7845, Haifa 31074, Israel.
