Abstract
Objective: The purpose of this study was to survey and to evaluate our early results with the cementless ZMR hip prosthesis.
Methods and Patients: This modular system is designed to address the challenges and design goals of hip revision with off-the-shelf flexibility, proximal-distal extensive fixation and restoration of hip kinematics (offset, lengths and anteversion). The Taper femoral component is designed for distal fixation using a distal stem that is tapered to help obtain secure, consistent seating in the femoral canal, and splints that engage bone to provide rotational stability. The porous stem is designed to provide proximal or extensive (both proximal and distal) fixation. The geometry of the modular proximal body is designed to help preserve bone. The taper junction between the proximal body and distal stem allows for control of version of the implant. Eighteen ZMR taper hip prostheses were implanted between January 2004 and August 2005. The mean age of the 18 patients (13 females, 5 males) was 72 and the mean follow-up period was 10 months.
Results: Out of these 18 patients, 4 interventions were primary (DDH or pathological fractures) and 14 were revision procedures. In most (16) cases a taper stem was used. In 14 cases a total hip revision was performed, in 2 cases only the femoral stem was revised and in 2 cases a bipolar Hemiarthroplasty was done. Operative time averaged 187±33 minutes.
The stem displayed an excellent distal fixation, clinically and radiologically. Much less complications were noted, compared to earlier series. Three patients had postoperative infections – one case was after a 2 stage revision of an infected implant, one case was associated with a large hematoma due to excessive anticoagulation and another case was a superficial infection that resolved. Other complications included 2 (11%) early dislocations and one femoral nerve palsy. There were no intraoperative fractures of perforations and none of these complications necessitated implant removal.
Conclusion: The excellent distal fixation, simplicity of the operative technique and modularity of stem length and diameter, body size and offset, and anteversion, makes this system an attractive solutions for a wide variety of difficult femoral revisions. The high rate (11%) of early dislocations is still lower than other series with this system.
The abstracts were prepared by Orah Naor, IOA Co-ordinator and Secretary. Correspondence should be addressed to Israel Orthopaedic Association, PO Box 7845, Haifa 31074, Israel.
