William C. Head

Extensor mechanism reconstruction with an allograft after total knee arthroplasty.

The authors report on a series of 15 knees in which an extensor mechanism allograft was used to treat a rupture of the patellar tendon associated with a total knee arthroplasty. Nine of the knees have greater than two-year follow-up evaluation (average, 4.1 years; range, 2.3-7 years). Postoperatively, the average flexion was 106 degrees. All but three patients achieved full passive extension. Six of the nine knees had no extensor lag. The average post-operative clinical score for the follow-up group was 78 points. Graft complications include one early graft rupture, one early quadriceps junction failure, and one patellar component loosening. One graft fractured after revision of a metal-backed patella.

Cortical strut allografts in the reconstruction of the femur in revision total hip arthroplasty. A basic science and clinical study.

Repeated total hip arthroplasties cause a loss of bone stock that will produce diminished component support, and can compromise implant function. There is, therefore, a compelling argument to return bone stock to the femur at the time of revision arthroplasty. Cortical strut allografts serve this purpose. They unite consistently and reliably, by 8.4 months on average. The overall rate of strut union is 96.6%. The sequence of healing events starts with round-off, followed by partial bridging and complete bridging. The repair process includes remodeling of the host femur, as well as the graft. Although there is variable resorption of some grafts, usually where not opposed to the host bone, there is also extension of others from host callus build-up such that, on average, there is no significant measurable loss of graft length or width. Most of the allograft struts, 78%, maintained a radiodense appearance. Clinical results of femoral revision with strut allografting have shown satisfactory end results compared with historic controls, with an average Harris score of 79.6 and a 2.7% subsidence rate. Of particular note is that the subsidence rate and clinical scores did not vary with the state of the preoperative femur, as has been shown repeatedly in the past. The canine model shows that the strut allografts are biologically active. Through mobilization of mesenchymal tissue, they are transformed into vascularized calluslike structures while maintaining good strength, and then further remodel to lamellar bone.

Reconstruction of patellar tendon rupture after total knee arthroplasty with an extensor mechanism allograft.

Although patellar tendon rupture after total knee arthroplasty (TKA) is a rare complication, the consistently poor outcome of conventional tendon repair has convinced some to abandon such reconstruction in favor of a prospective protocol using an allograft distal extensor mechanism. The graft consists of a quadriceps tendon, a patella with a cemented prosthesis, a patellar tendon, and a tibial tubercle. Since December 1985, 13 knees in 12 patients were reconstructed using this method. Ten knees were followed for six to 51 months; five of these knees were followed for more than 24 months. Knee extension power and improved function were ultimately attained in all cases, although minimal extensor lags were present in three cases. Preoperative motion returned in all but one knee. Healing of the allograft to the host tissue was attained primarily at all of the tibial junctions. Two graft complications occurred, both in the first three months after surgery: one quadriceps junction treated by resuture failed at the one-month mark, and the other graft had to be revised for extensor weakness from rupture of the graft at the patella-patellar tendon junction, which was attributed to surgical damage to the tendon. After completion of healing to the host and rehabilitation of the knee joint, no grafts in the series failed during the course of normal daily activities. One patient fractured the allograft patella in a severe fall. The long-term durability of this construct needs to be studied further.

Effect of circumferential plasma-spray porous coating on the rate of femoral Osteolysis after total hip arthroplasty

BACKGROUND Osteolysis of the femur has been a serious problem associated with some designs of total hip-replacement implants; it frequently leads to failure of the femoral component. We evaluated the effect of a circumferential plasma-spray porous coating on the rate of osteolysis in a study that included two groups of hips, each of which received an implant with the same design except for the extent of the porous coating. Our goal was to determine the possible role of circumferential porous coating in protecting the bone-implant interface from osteolysis. METHODS A series of consecutive primary total hip replacements performed with insertion of the Mallory-Head implant without cement was divided into two study groups. The first 126 hips (Group 1) were treated with a femoral stem that had a noncircumferential plasma-spray porous titanium coating. The next ninety hips (Group 2) were treated with a circumferentially coated stem of the same design. The average duration of radiographic follow-up was 7.8 years in Group 1 and 7.5 years in Group 2. RESULTS The average rate of polyethylene wear was similar for the two groups (0.187 millimeter per year in Group 1 and 0.189 millimeter per year in Group 2). The prevalence of osteolysis in Group 1 (40 percent; fifty of 126 hips) was significantly higher than that in Group 2 (10 percent; nine of ninety hips) (p < 0.001). Osteolysis remote from the joint space (distal to zones 1 and 7) was found in 11 percent (fourteen) of the hips in Group 1 but in none of those in Group 2 (p = 0.0004). The average total area of osteolysis in Group 1 (5.0 square centimeters) was significantly larger than that in Group 2 (2.9 square centimeters) (p < 0.05). CONCLUSIONS A circumferential plasma-spray titanium porous coating on the femoral component of a total hip-replacement prosthesis inserted without cement appears to provide an effective barrier preventing wear debris from gaining access to the endosteal surface of the femur and the greater trochanter. This finding supports the hypothesis of the so-called effective joint space, which predicts that wear debris from the joint bearing can migrate, driven by intracapsular pressures, to all areas to which joint fluid has access and thus can result in osteolysis. The reduction of the prevalence of osteolysis and the elimination of osteolysis from the zones remote from the joint space by the use of a circumferential plasma-spray porous coating indicates that the femur was effectively sealed off from the joint space. We believe that the durability and longevity of the femoral component should be enhanced by the use of such a coating.

Clinical and Radiographic Outcome of a Cementless, Titanium, Plasma Spray-coated Total Hip Arthroplasty Femoral Component Justification for Continuance of Use

Between 1984 and 1986, 177 nonconsecutive, primary total hip arthroplasties were performed in 150 patients using the Mallory-Head Porous femoral component (Biomet, Warsaw, IN) inserted without cement. Average time to follow-up evaluation for the entire population (including all early revisions) was 76 months (6.3 years). There were 10 revisions (6%) with an average time to revision of 50 months (4.2 years). Two revisions were for component undersizing; three revisions were for aseptic loosening; four revisions were for acetabular component failure and one revision was due to a femoral fracture secondary to trauma. At the most recent follow-up visit, the average Harris hip score for all hips increased from 41.5 before surgery to 86.8 (P < .001). Radiographic assessments yielded an average Engh fixation score of 20.7. The Kaplan-Meier survival estimate for the average time to follow-up evaluation was 0.98. Based on our patient selection criteria and excellent intermediate clinical and radiographic results, the initial design strategies of the Mallory-Head Porous femoral prosthesis have been confirmed.

Proximal femoral allografts in revision total hip arthroplasty.

Patients with total hip arthroplasty (THA) and aseptic loosening associated with severe bone deficiency were treated with freeze-dried bone allografts of the proximal one-third of the femur. Twenty-two of the first 25 patients were available for review with an average follow-up period of 28 months. Significant functional improvement was obtained in 16 patients (73%). The following complications occurred with allograft revisions: dislocation, wound hematoma, joint instability, nonunion, implant failure, and acetabular loosening. Nine patients required additional surgical procedures. There have been no infections or rapid lysis indicative of an allograft rejection phenomenon. The 73% success at the two-year postoperative interval of incorporation of freeze-dried allografts for salvage situations has been encouraging. However, the long-term durability of these grafts is not known and will require further follow-up study.

Tapered design for the cementless total hip arthroplasty femoral component

The long-term behavior of total hip arthroplasty ultimately is determined by adaptive bone remodeling. Stress adaptation creating various degrees of metaphyseal bone atrophy has occurred with prostheses designed for tight distal fit and fill. This phenomenon has been explained as bone adaptation resolving the conflict between femoral component stiffness and bone flexibility. However, clinical observations indicate that a different premise may be operational when prostheses with tapered geometries are used. The results of four published reports (748 arthroplasties) using cementless femoral components of a tapered design were reviewed. The review found a low incidence of aseptic loosening (0.5%) and significant thigh pain (0.5%), and a radiographic incidence of proximal bone atrophy of 6%. In no case was the metaphyseal bone atrophy described as severe or extensive. These findings challenge the premise that reactive bone adaptation is related to the issues of femoral component stiffness exclusively and propose that femoral component geometry may have an influence on bone adaptation.

Thirteen year results of total hip arthroplasty using a tapered titanium femoral component inserted without cement in patients with type C bone.

Although cementless arthroplasty with a tapered titanium femoral component has proven reliable in young patients with excellent bone quality, studies involving patients with poor bone quality are lacking. The present study evaluates the results of total hip arthroplasty (THA) using such a femoral component in patients with Type C femoral bone. Ninety-two THAs were performed in 81 patients aged 65 years and older using a tapered titanium cementless femoral component. Follow-up in 62 patients (72 hips) averaged 13.2 years (minimum, 10 years); 19 patients were lost to follow-up. According to Doors criteria, 20 femora were classified as Type A, 19 as Type B, and 33 as Type C. No stem was revised because of stem instability, thigh pain, or osteolysis. One stem was removed because of sepsis. Six acetabula were revised because of polyethylene wear and periacetabular osteolysis. Four patients reported mild thigh pain. Radiologic signs of osseous integration for cylindrical extensively porous coated cobalt-chrome femoral components are not valid for tapered titanium designs.

Surgical closing in primary total knee arthroplasties : Flexion versus extension

One hundred eight consecutive patients with primary osteoarthritis of the knee undergoing primary arthroplasty were compared retrospectively to determine whether surgical closure of the entire wound in flexion has any effect on range of motion postoperatively over a period of up to 6 months. The knees of the first 52 patients were surgically closed in extension. In the second group of 56 patients, the knees were closed in 90 ° to 110 ° flexion depending on the available motion of the joint. Although the patients were not randomized, the groups were closely matched in age, weight, height, and gender. Preoperative and postoperative patellar heights were similar in both groups. The patients were started on a continuous passive motion device in the recovery room. At all intervals the flexion measurements were significantly better in the flexion closure group. By 6 months the flexion closure group had surpassed their preoperative measurements, whereas the extension closure group had not yet achieved this goal. The flexion group required less home physical therapy than the extension group. Closing the knee in flexion permits the patients to regain knee motion faster with less effort, thereby saving money and enhancing patient satisfaction.

Structural bone grafting for femoral reconstruction.

Structural grafting for femoral reconstruction has been used in femoral revision surgery in connection with partial bone loss. In patients in whom the proximal femur is compromised significantly circumferentially, or is entirely absent, segmental proximal femoral allografts are indicated. Onlay cortical allografts have been used to supplement bone stock when the intact femur has advanced noncircumferential deficiencies attributable to osteoporosis, osteolysis, or other causes. The procedure using proximal femoral allografts was performed in 262 patients from 1983 to 1997. Satisfactory results were obtained in 85% of the patients. More than 1000 cortical onlay bone plate allografts were performed from 1984 to 1997. Detailed information was obtained on 251 patients who underwent surgery from 1984 to 1990. These constructs reliably united with the host bone and increased bone mass long-term.