The use of a tripolar articulation in revision total hip arthroplasty: a minimum of 24 months' follow-up.

A retrospective cohort study of 31 hips revised with a tripolar articular construct was performed. Patient demographics and preoperative and postoperative information were recorded. Indications for a tripolar construct were recurrent dislocation and the inability to attain intraoperative stability during hip revision. Nine patients (29%) were revised to the tripolar construct after failure of a constrained liner. Twenty patients (65%) had at least one episode of instability before the most recent revision. At a mean follow-up of 38 months, modified Postel scores improved from a mean of 5.28 to 9.64 (P < .01). Radiographic follow-up revealed no evidence of component loosening/migration, osteolysis, or polyethylene wear. Two patients (7%) required further revision surgery for recurrent instability. A tripolar construct was effective in eliminating or preventing instability in 93% of the complex cases treated. These early results support the use of a tripolar construct in treating recurrent instability or instability encountered at the time of revision hip arthroplasty.

The use of tantalum porous metal implants for Paprosky 3A and 3B defects.

Complex acetabular defects are difficult to reconstruct. For severe pelvic defects, tantalum metal acetabular implants may provide a viable solution over traditional implants. This short-term follow-up reviews 43 acetabular revisions treated with tantalum acetabular implants. These revisions included 33 Paprosky type 3A defects, involving 30% to 50% of host acetabulum loss, and 10 type 3B defects, having similar or greater bone loss with a pelvic discontinuity. Tantulum acetabular modular augments were used in 26 cases to support the shell. At a mean of 2.8 years' follow-up, 42 components were stable, and 1 failed because of septic loosening. The overall success rate was 98%. One revision was performed because of loosening secondary to sepsis; none were performed for aseptic loosening. Implants made from highly porous tantalum metal provide a surface that is highly conducive to bone ingrowth. Combined with the ability to use modular augments for added support and stability, this technology may change the way major defects are reconstructed.

A randomized, prospective study of primary total knee components designed for increased flexion.

This prospective, randomized study reports early results for range of motion (ROM) after primary total knee arthroplasty. Group A received standard posterior-stabilized (PS) implants. Group B had PS implants designed for increased flexion. Average preoperative ROM was 2 degrees to 121 degrees for group A and 1.8 degrees to 122 degrees for group B. At 12-month follow-up, average ROM for group A was 0.6 degrees to 120 degrees as compared with 0.6 degrees to 133 degrees for group B (P < .05). Significantly more patients in group B flexed more than 135 degrees (P < .05). Furthermore, 12 patients (48%) in group A failed to return to preoperative ROM versus 2 patients (8%) in group B (P < .05). Although long-term follow-up is desirable, these early results support the use of PS implants designed for increased flexion.

Porous-ingrowth revision acetabular implants secured with peripheral screws. A minimum twelve-year follow-up.

BACKGROUND: During revision total hip arthroplasty, the acetabular component is often secured with screws to ensure initial press-fit stability. The purpose of the present study was to assess a series of acetabular revisions involving the use of a porous-coated acetabular component that was stabilized with peripheral screws and to evaluate the results in relation to the acetabular bone deficiencies that were present at the time of the revision procedure. METHODS: From 1987 to 1991, 203 consecutive acetabular revisions were performed. In 142 hips, a severe acetabular bone deficiency that did not require an allograft was reconstructed with a porous-coated acetabular cup that was secured with a minimum of two peripheral screws. After an average duration of follow-up of 13.2 years, 134 hips were reviewed clinically and radiographically. The procedure was considered to be a clinical failure if the component was revised or if the postoperative clinical scores were poorer than the preoperative scores. RESULTS: At the time of the most recent follow-up, 127 (95%) of the 134 hips were stable and clinically successful. The other seven hips (5%) were considered to have failed. Five of these seven hips failed because of an infection, and two failed because of aseptic loosening. Five (19%) of the twenty-seven hips with a Paprosky type-3A defect (a defect in which 30% to 50% of the host acetabulum is missing) failed. CONCLUSIONS: Revision total hip arthroplasty with use of a porous-coated acetabular component that is fixed with peripheral screws can provide long-term durability in hips with severe acetabular defects that do not require the use of an allograft (Paprosky type-1 and type-2 defects). We recommend that when an acetabular implant with peripheral screws is used for the treatment of a more severe (type-3) defect, the cup should be augmented with structural allograft to improve initial stability, or other implants should be utilized.

Osteochondral autograft transplantation in the porcine knee.

BACKGROUND: Knee articular cartilage defects are not an uncommon problem. Because articular cartilage is limited in its ability to heal, these defects are difficult to manage. HYPOTHESIS: Osteochondral autografts will provide less of a cavitary defect and more viable hyaline articular cartilage than will control knees. STUDY DESIGN: Controlled laboratory study. METHODS: Osteochondral autografts were grossly and microscopically evaluated in the porcine knee and compared with a control at 6 weeks, 3 months, and 6 months. In 18 porcine specimens, a 1-stage surgical procedure was performed to harvest an osteochondral graft from a nonweightbearing articular cartilage surface, and the graft was transplanted into a defect created in the weight-bearing region of the medial femoral condyle. In the opposite control knee, a similar defect was created in the medial femoral condyle; an osteochondral transplant was not performed. Six pigs each were sacrificed at 6 weeks, 3 months, and 6 months. RESULTS: Gross inspection of the control knees showed a cavitary defect. The defect grossly decreased in size with fibrous ingrowth seen on microscopic analysis. An increasing amount of fibrous tissue and fibrocartilage was present at the 3 time periods. Gross inspection of the graft knee showed a healed osteochondral plug with no obvious displacement, cavitary defects, or surrounding necrotic tissue at each time interval. Microscopic analysis revealed the graft knee contained viable hyaline cartilage and healed viable subchondral bone. At all time intervals, 75% to 100% of the hyaline cartilage was viable in all specimens. In 6-month specimens, bridging cartilage at the autograft-host junction was incomplete in 50%, partial in 33%, and complete in 17%. CONCLUSION: Osteochondral autografts in the porcine knee resulted in viable hyaline cartilage for up to 6 months; there was inconsistent bridging hyaline cartilage at the periphery. Grafts appeared to heal into existing subchondral bone without displacement or evidence of necrosis. CLINICAL RELEVANCE: This type of osteochondral transplant can be used as a reliable reconstructive alternative for osteochondral defects.

The early dislocation rate in primary total hip arthroplasty following the posterior approach with posterior soft-tissue repair.

Although a posterior approach is frequently used for total hip arthroplasties (THAs), some reports have associated this approach with higher dislocation rates than anterior or lateral approaches. To deter dislocations following primary THAs using the posterior approach, the senior author repairs the posterior capsule and the short external rotators to the greater trochanter with nonabsorbable suture. We retrospectively reviewed the occurrence of dislocations among 945 primary THAs performed with this technique at a mean 6.4-year follow-up (range, 2.0-9.3 years). The average patient age was 62.3 years (range, 36-86 years). Eight patients (0.85%) dislocated. Of these, 3 dislocated within the first postoperative year and were treated without surgery; 3 required revision surgery and placement of a constrained liner; and 2 dislocated after trauma and were treated without surgery. With the correct orientation of components and an enhanced soft-tissue repair, the posterior surgical approach can result in an extremely low dislocation rate.

Minimal 11-year follow-up of extensively porous-coated stems in femoral revision total hip arthroplasty.

Between 1984 and 1989, 188 consecutive femoral revision surgeries were performed. Eighteen patients died or were lost to follow-up, and the remaining 170 patients were followed for 11 to 16 years (mean, 14.2 years). Radiographic evidence of a bone ingrown stem was present in 82% of the hips, stable fibrous fixation was present in 14% of the hips, and 4% of the hips were unstable. Six stems were revised to a larger, fully coated cementless implant. Proximal femoral osteolysis was seen in 23% of femora but was limited to Gruen zones 1 and 7. No diaphyseal osteolysis was seen. The overall mechanical failure rate in this series was 4.1%. Failure of fixation correlated highly with extent of bone loss present at the time of surgery. On the basis of the radiographic and clinical results at a mean follow-up of 14.2 years, we recommend the use of extensively coated femoral stems in revision hip arthroplasty.