Introduction:

Non-hinged constrained condylar components (CCK) may be used for primary TKA in presence of severe deformity, fixed contractures and ligamentous laxity. Several authors have recommended use of stem extensions to accompany CCK type of components. However, use of stem extensions in primary TKA, not only invades the medullary canal, but may also be associated with increased surgical time, implant cost, and thigh or leg pain. The purpose of this study was to assess the short-term outcomes of primary CCK knees without stem extensions and to compare this to a control group of standard posterior stabilized (PS) knees, otherwise using the same implant design.

Background:

Dual mobility components in total hip arthroplasty have been successfully in use in Europe for greater than 25 years. However, these implants have only recently obtained FDA approval and acceptance among North American arthroplasty surgeons. Both decreased dislocation rate and decreased wear rates have been proposed benefits of dual mobility components. These components have been used for primary total hip arthroplasty in patients at high risk for dislocation, total hip arthroplasty in the setting of femoral neck fracture, revision for hip instability, and revision for large metal-on-metal (MoM) hip articulation. The literature for the North American experience is lacking.

Background

Revision surgery for failed metal-on-metal (MOM) total hip arthroplasty (THA) or hip resurfacing (HR) has been a challenge. Previous studies have reported high failure and complication rates, including dislocation, infection, aseptic loosening and lower patient satisfaction. Options for revision depend on the integrity and stability of the femoral and acetabular components. When both components fail, full revision is required; however, when the acetabular component remains well fixed and oriented, only the isolated femoral component revision can be performed. Dual mobility components can be utilized to match the size to the inner diameter of the metal cup. With the dual mobility implant, the morbidity and complications associated with cup revision are avoided while maintaining a natural femoral head size and potentially increasing range of motion and stability postoperatively compared to standard THA.

Introduction and Aims: The use of porous coated femoral stems in revision hip arthroplasty has been associated with a high rate of complications including femoral fracture, femoral perforation and eccentric reaming. The purpose is to determine if using a distally slotted-fluted femoral stem is associated with lower incidence of the above three intra-operative complications.

Method: The intra-operative complications of 175 cementless revision total hip arthropasties (THA) using a distally slotted-fluted femoral stem were reviewed. Three categories of complications were recorded: femoral fracture, femoral perforation and eccentric reaming. Radiographic evaluation was based on standard antero-posterior and lateral views of the hip joint performed in the intra-operative or immediate post-operative period. Statistical analysis for factors associated with complications was performed using the chi-square test.

Results: Intra-operative complications occurred in 16 patients (9.1%). There was no statistically significant association between complication rate and type of surgical approach, stem length, stem diameter, or host bone quality. The complication rate was significantly lower than the 44% total complication rate previously reported utilising a long, solid, extensively coated revision stem without a slot or flute (p< .01). These results are consistent with laboratory testing, which revealed significantly lower bone strains at the isthmus when inserting a long cementless revision stem with a slot and flute compared to a solid fully coated stem of identical geometry.

Conclusion: The use of a distally slotted fluted porous coated femoral stem in revision hip arthroplasty results in a dramatically lower complication rate compared to rates previously reported for solid porous stems. These results strongly support the continued use of such a prosthesis for revision THA.