Limits...
Short-Term Results of Novel Constrained Total Hip Arthroplasty.

Pace T, Finley S, Snider R, Looper J, Tanner S - Orthop Rev (Pavia) (2015)

Bottom Line: One patient showed radiographic evidence of 1 mm polyethylene wear.Harris Hip Scores improved from a mean of 68.8 (range 58-87) preoperatively to 98.9 (range 65-100) at final clinical assessment.This constrained acetabular prosthesis had a dislocation rate of less than 2%, with 0% component failure rate at a minimum of 2 years of follow-up suggesting this prosthesis may be a viable alternative for patients at risk for instability or those known to have recurrent instability.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopedic Surgery, Greenville Health System , SC, USA ; University of South Carolina School of Medicine , West Columbia, SC, USA.

ABSTRACT
Constrained acetabular components have only been recommended as a salvage option for the persistently unstable total hip arthroplasty (THA), due to limited range of motion and less than satisfactory component failure rates. This is a retrospective review of 137 patients with 154 consecutive primary constrained THAs performed between November 2003 and August 2007. We reviewed serial radiographs, postoperative complications, groin/thigh pain, and compared preoperative and postoperative Harris Hip Scores. With a mean follow-up of 6 years, there was 1.9% dislocation rate, 0% component failure rate, and 2.6% infection rate. Seven patients reported continued groin pain, and three had continued thigh pain. One patient showed radiographic evidence of 1 mm polyethylene wear. Radiographic review showed no evidence of osteolysis or stem subsidence. Harris Hip Scores improved from a mean of 68.8 (range 58-87) preoperatively to 98.9 (range 65-100) at final clinical assessment. This constrained acetabular prosthesis had a dislocation rate of less than 2%, with 0% component failure rate at a minimum of 2 years of follow-up suggesting this prosthesis may be a viable alternative for patients at risk for instability or those known to have recurrent instability.

No MeSH data available.


Related in: MedlinePlus

A) Zimmer Epsilon Constrained Cup and Natural Stem; B) Zimmer Epsilon Constrained Liner (Warsaw, IN, USA).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4508557&req=5

fig001: A) Zimmer Epsilon Constrained Cup and Natural Stem; B) Zimmer Epsilon Constrained Liner (Warsaw, IN, USA).

Mentions: Institutional Review Board approval was obtained for this retrospective review of clinical records, outcomes and radiographs of 137 patients with 154 consecutive primary constrained hip arthroplasties performed by the senior author between November 2003 and August 2007. All arthroplasties were performed through a posterolateral approach, and bilateral procedures were staged. Mean patient age was 64 (range 34-89 years), with the majority under the age of 65. Seventy-three of the patients were male, and eighty-five procedures were conducted on right hips. Osteoarthritis was the principal diagnosis in 149 hips, avascular necrosis in four, and one THA was done for fracture. Primary constrained THA patients with a minimum of two years of clinical and radiographic follow-up were included. The average follow-up was 6 years (range 2-10 years). The arthroplasty components utilized in each patient were identical, consisting of a press fit porous titanium acetabular shell (Zimmer Epsilon®) and modular tapered proximal in-growth femoral stem (Zimmer Natural Hip™ stem; Figure 1A). All acetabular shells, except one, were secured with a minimum of 1 screw. The constrained liner (Zimmer Longevity® Constrained Liner) utilized is remarkable due to the polyethylene cutouts, leading to extended cup geometry only between the 11 and 1 o’clock position as well as the 4 and 8 o’clock position (Figure 1B). The polyethylene liner was highly cross-linked ultra high molecular weight polyethylene (UHMWPE) with an introitus smaller than the femoral head. The liner couples with a constraining ring that decreases its ability to deform, increasing the force required to dislocate the femoral head from the constrained liner. This makes the component unique in that it is a constrained THA with recesses strategically positioned to provide significant improvements in flexion, internal rotation, extension and external rotation while maintaining femoral head constraint. Dependent upon acetabular cup abduction and anteversion, the reported ROM of this construct is 111-137° of flexion, 21-45° internal rotation at 90° of flexion and 34-49° external rotation at 0° flexion before prosthetic impingement. This concomitantly reports 243% increased torque to dislocation compared to fully circumferential constrained components.12,13


Short-Term Results of Novel Constrained Total Hip Arthroplasty.

Pace T, Finley S, Snider R, Looper J, Tanner S - Orthop Rev (Pavia) (2015)

A) Zimmer Epsilon Constrained Cup and Natural Stem; B) Zimmer Epsilon Constrained Liner (Warsaw, IN, USA).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508557&req=5

fig001: A) Zimmer Epsilon Constrained Cup and Natural Stem; B) Zimmer Epsilon Constrained Liner (Warsaw, IN, USA).
Mentions: Institutional Review Board approval was obtained for this retrospective review of clinical records, outcomes and radiographs of 137 patients with 154 consecutive primary constrained hip arthroplasties performed by the senior author between November 2003 and August 2007. All arthroplasties were performed through a posterolateral approach, and bilateral procedures were staged. Mean patient age was 64 (range 34-89 years), with the majority under the age of 65. Seventy-three of the patients were male, and eighty-five procedures were conducted on right hips. Osteoarthritis was the principal diagnosis in 149 hips, avascular necrosis in four, and one THA was done for fracture. Primary constrained THA patients with a minimum of two years of clinical and radiographic follow-up were included. The average follow-up was 6 years (range 2-10 years). The arthroplasty components utilized in each patient were identical, consisting of a press fit porous titanium acetabular shell (Zimmer Epsilon®) and modular tapered proximal in-growth femoral stem (Zimmer Natural Hip™ stem; Figure 1A). All acetabular shells, except one, were secured with a minimum of 1 screw. The constrained liner (Zimmer Longevity® Constrained Liner) utilized is remarkable due to the polyethylene cutouts, leading to extended cup geometry only between the 11 and 1 o’clock position as well as the 4 and 8 o’clock position (Figure 1B). The polyethylene liner was highly cross-linked ultra high molecular weight polyethylene (UHMWPE) with an introitus smaller than the femoral head. The liner couples with a constraining ring that decreases its ability to deform, increasing the force required to dislocate the femoral head from the constrained liner. This makes the component unique in that it is a constrained THA with recesses strategically positioned to provide significant improvements in flexion, internal rotation, extension and external rotation while maintaining femoral head constraint. Dependent upon acetabular cup abduction and anteversion, the reported ROM of this construct is 111-137° of flexion, 21-45° internal rotation at 90° of flexion and 34-49° external rotation at 0° flexion before prosthetic impingement. This concomitantly reports 243% increased torque to dislocation compared to fully circumferential constrained components.12,13

Bottom Line: One patient showed radiographic evidence of 1 mm polyethylene wear.Harris Hip Scores improved from a mean of 68.8 (range 58-87) preoperatively to 98.9 (range 65-100) at final clinical assessment.This constrained acetabular prosthesis had a dislocation rate of less than 2%, with 0% component failure rate at a minimum of 2 years of follow-up suggesting this prosthesis may be a viable alternative for patients at risk for instability or those known to have recurrent instability.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopedic Surgery, Greenville Health System , SC, USA ; University of South Carolina School of Medicine , West Columbia, SC, USA.

ABSTRACT
Constrained acetabular components have only been recommended as a salvage option for the persistently unstable total hip arthroplasty (THA), due to limited range of motion and less than satisfactory component failure rates. This is a retrospective review of 137 patients with 154 consecutive primary constrained THAs performed between November 2003 and August 2007. We reviewed serial radiographs, postoperative complications, groin/thigh pain, and compared preoperative and postoperative Harris Hip Scores. With a mean follow-up of 6 years, there was 1.9% dislocation rate, 0% component failure rate, and 2.6% infection rate. Seven patients reported continued groin pain, and three had continued thigh pain. One patient showed radiographic evidence of 1 mm polyethylene wear. Radiographic review showed no evidence of osteolysis or stem subsidence. Harris Hip Scores improved from a mean of 68.8 (range 58-87) preoperatively to 98.9 (range 65-100) at final clinical assessment. This constrained acetabular prosthesis had a dislocation rate of less than 2%, with 0% component failure rate at a minimum of 2 years of follow-up suggesting this prosthesis may be a viable alternative for patients at risk for instability or those known to have recurrent instability.

No MeSH data available.


Related in: MedlinePlus