Cementless femoral revision arthroplasty of the hip: minimum 5 years followup.

Durable fixation of the femoral component to the bone in femoral revision arthroplasty of the hip is the main ingredient to a successful reconstruction. Because of poor durability of cemented fixation in revision, in 1984, one author began to use cementless fixation with extensively porous-coated chrome cobalt stems. The current authors report the durability of that fixation technique in 137 hips (134 patients) followed up 5 to 16 years. With a mean followup of 9.3 years, 10 (7%) of the stems have been removed. Five (4%) were removed for fixation problems and five (4%) were removed for infection. Using the radiographic criteria of Engh et al, 83% of the stems achieved bony ingrowth. No late failure of fixation was observed. Canal-filling prostheses were more likely to have bone ingrowth as were stems placed in femurs with lesser degrees of bone stock deficiency. Significant thigh pain was seen in 7% of bone ingrown stems, 16% of stable fibrous fixated stems, and 75% of unstable stems. Significant thigh pain in bone ingrown stems was observed more commonly in osteoporotic femurs and bone stock deficient femurs. Severe stress shielding correlated with preoperative osteoporosis and larger diameter stems but has not caused failure. Excellent durability of this fixation technique is evident.

The John Charnley Award. Wear is a function of use, not time.

Polyethylene wear (linear penetration) in 37 hip replacements was assessed from digital images using a validated two-dimensional, edge detection-based computer algorithm. Patient activity was assessed with a pedometer, a step activity monitor and a simple visual analog scale. Joint use was related to wear at the 90% confidence level. Without three recognized outliers, wear was highly correlated to use. The visual analog scale activity rating was significantly related to wear for the 24 hip replacements with standard polyethylene. Univariate regression analysis indicated that male gender, height, weight (which were both highly correlated to male gender) and hip center of rotation were significantly correlated to wear. Multivariate regression analysis indicated that male gender, femoral off-set, and Hylamer were significantly correlated to wear. Based on the wear and activity data from the 24 hip replacements with standard polyethylene, the average volumetric wear rate per million cycles with a 70 kg patient weight was 30 mm3. This unique in vivo result can be considered a target wear rate for standard polyethylene in hip simulator studies.

Femoral revision hip arthroplasty with uncemented, porous-coated stems.

One hundred seventy-five cementless femoral hip revision surgeries with extensively porous-coated stems and 161 concomitant acetabular revisions done from 1984 to 1991 were retrospectively reviewed. Average age at surgery was 62.4 years. Followup ranged from 2 to 10 years (average, 5 years). One hundred sixty-eight femoral components (96%) remain in place. Two unstable components, 1 stable fibrous component, and 1 bone ingrowth component were painful and required rerevision. Two femoral components were removed as part of resection arthroplasties for repetitive acetabular failure caused by pelvic dissociation. One component was removed for late hematogenous infection. Using the Engh radiographic criteria, femoral stems were judged to have achieved bony ingrowth in 82.8% (n = 174) of the cases. Bony ingrowth occurred more frequently when the canal was filled with the prosthesis and with lesser degrees of bone stock deficiency. Severe stress shielding occurred in 11 (7.6%; n = 144) of the bone in-grown cases and correlated with preoperative osteoporosis and larger diameter prosthesis. Significant thigh pain was less common in the bone ingrown (4.2%; n = 144) than in the stable fibrous group (18.5%; n = 27). Significant thigh pain in bone ingrown stems was more likely to occur with osteoporotic and bone stock-deficient femurs. To date, significant wear and osteolysis have not been observed.

Acetabular reconstruction with a threaded prosthesis for failed total hip arthroplasty.

The MEC-Ring threaded acetabular component was used in 35 patients for revision of failed cemented hip arthroplasties, and 32 have been observed for two to four years (mean, 2.5 years). With only a short-term follow-up period, 44% of patients have already required revision for failure of the MEC-Ring acetabular component. Patients with especially poor acetabular bone stock that had had structural bone graft had a significantly higher rate of failure. The authors developed a technique of supine oblique roentgenograms that allowed better visualization of the component-bone interface. Eighty-six percent of patients had radiolucencies, and 67% of these were progressive. The presence of progressive radiolucencies, component migration, or both was associated with a higher failure rate. Progressive radiolucencies were also associated with a worse pain score in patients whose arthroplasties have not failed. The MEC-Ring threaded component is not recommended for revision hip arthroplasty, especially in cases with poor acetabular bone stock.

Catastrophic wear of tibial polyethylene inserts.

A number of factors play an important role in the wear-resistance of tibial polyethylene inserts. Among these are manufacturing processes that adversely affect the wear-resistance of polyethylene (such as heat treatments to the articular surface or gamma irradiation used for sterilization), tibio-femoral articular geometry, polyethylene thickness, knee alignment, femoral-component-bearing surface material, modularity of the tibial inserts and tibial trays, and quality of the polyethylene itself. The authors report an unusually high rate of failure by wear of tibial polyethylene inserts from a series of 176 Porous Coated Anatomic (PCA) knees in which there were eight revisions (4.5% of the series) performed for tibial polyethylene wear at an average of 60 months. Nine additional knees (5.1%) had thinning of greater than 30% of the initial polyethylene thickness. Four of the unsuccessful knees revealed areas of osteolysis filled with membranes containing large amounts of particulate polyethylene. In addition to the 176 knees from a series from a Los Angeles university, the cases of five other knees in four patients who came for treatment from outside hospitals with full-thickness wear of the tibial polyethylene are discussed. One of these five knees was a cementless PCA knee that developed massive osteolysis in response to the particulate polyethylene debris.

Mechanisms of failure in total knee arthroplasty.

The major mechanisms of failure in total knee arthroplasty are loosening, instability, sepsis, extensor mechanism power loss, poor range of motion, bone fractures, and prosthesis fracture. These are, for the most part, within the surgeon's control. Prosthetic alignment is the most important factor influencing postoperative loosening and instability.

Radiographic analysis of the axial alignment of the lower extremity.

The axial alignment of the lower extremities of twenty-five normal male volunteers whose mean age was thirty years was studied using a standardized radiograph of the entire lower extremity. The extremities were found to be in a mean of 1.5 degrees (right) and 1.1 degrees (left) of varus angulation at the knee between the tibial and femoral mechanical axes. The transverse axis of the knee lacked a mean of 3.0 degrees (right) and 2.6 degrees (left) of being perpendicular to the mechanical axis of the tibia. The anatomical axis of the femur did not pass through the center of the knee.

Treatment of acute femoral neck fractures with total hip arthroplasty.

Between 1973 and 1983, 27 patients with acute femoral neck fractures were treated at the UCLA Medical Center with total hip arthroplasty. These cases were selected on the basis of age, high activity level, and degenerative changes in the acetabular cartilage. The average age was 72 years. There were 19 women and eight men. The average follow-up period was 3.8 years with a range of one to ten years. Methods used included analysis of clinical data, roentgenograms, final pain ratings, walking ratings, and activity levels using the UCLA rating system. Pain relief and overall functional results were better than that of most series of acute femoral neck fractures treated with hemiarthroplasty and similar to that of total hip arthroplasty series. The complication rate was slightly less than both authors' elective total hip series, and considerably less than most hemiarthroplasty series. Complications included a superficial wound infection, a urinary tract infection, and a perforated colon diverticulum. Four patients died within one year from causes unrelated to the hip arthroplasty. There were no deep infections, dislocations, or reoperations. Total hip arthroplasty in selective cases of acute femoral neck fractures can give more consistent pain relief and better functional results than hemiarthroplasty, without an increase in complications.

Nutritional status and wound healing in lower extremity amputations.

This prospective study examines the importance of nutritional status in 41 consecutive patients with lower extremity amputations proximal to the Symes level. The nutritional status of the patients was assessed by evaluating serum albumin levels and total lymphocyte counts, proven indices of nutritional status. Fifteen of 16 patients with normal nutritional parameters healed their amputations uneventfully, whereas 11 of 25 malnourished patients suffered either local or systemic postoperative complications. The difference in the complication rate between the nourished and malnourished groups is statistically significant (p less than 0.05). Malnutrition adversely affects the prognosis for healing lower extremity amputations, but it seems to be less detrimental to wound healing in the more proximal amputations, where blood flow is superior. Based on these findings, it is recommended that patients being admitted for lower extremity amputation should be screened at the time of admission, and those with laboratory parameters indicative of malnutrition should have elective surgery postponed until their malnourished state is corrected. Patients requiring urgent surgical treatment should probably receive supplemental nourishment in the perioperative period.

The window technique for the removal of broken femoral stems in total hip replacement.

Removal of broken femoral stems continues to be a difficult technical procedure in hip replacement surgery, despite the development of metal drilling devices and special extractors placed into the drill hole. The window technique for the removal of broken femoral stems is technically easier than the metal drilling technique and does not require sophisticated instrumentation. This technique is also useful as a back-up procedure when metal drilling procedures fail.

Further experience with Grice subtalar arthrodesis.

Between 1952 and 1973, 302 Grice-type subtalar arthrodeses were performed with a minimum follow-up evaluation of two years and a maximum follow-up evaluation of 22 years. Seventy-three feet were followed more than ten years. Seventy-three percent of the 244 operations done for poliomyelitis residuals were considered satisfactory. The number of cases in other diagnostic groups ranged from six to 18 and showed unpredictable results. The major reasons for an unsatisfactory result were fusion in unacceptable position (usually varus) and nonunion of the arthrodesis. Correct positioning of the subtalar joint at surgery is essential for a satisfactory result, and recommendations are made as to how to obtain such a position. Minimal degenerative arthritis of adjacent joints occurred in feet fused in acceptable positions.

Fracture of a Charnley acetabular component from polyethylene wear.

A 42-year-old man incurred a fracture of the high-density polyethylene socket eight years after a Charnley arthroplasty with a 22 mm head. The excessive wear debris resulted in severe tissue reaction and included resorption of surrounding cancellous bone stock. Polyethylene component wear, occasionally seen in total hip arthroplasties, may be relatively more common in hip replacements that do not fail from loosening.

Fracture of a unicompartmental knee replacement femoral component.

Fracture of the femoral component of a unicompartmental knee replacement occurred ten years after the operation in a 69-year-old man. Fractures of femoral components are unusual and can occur when the metal is thin and weak or where there are areas of stress concentration.

Total hip arthroplasty. An investigation of factors related to postoperative urinary retention.

The predisposing factors to urinary retention in patients undergoing hip arthroplasty were investigated by a review of the charts of 272 patients. Age, sex, surgeon, choice and duration of anesthesia, volume of fluid replacement, and use of postoperative intramuscular narcotics did not correlate significantly with urinary retention. However, urinary retention increased from 24% to 62% with the use of epidural morphine for postoperative pain management.

New advances in bone research.

An edited summary of an Interdepartmental Conference arranged by the Department of Medicine, UCLA School of Medicine, Los Angeles. William M. Pardridge, MD, Associate Professor of Medicine, is Director of Conferences.

Infection after total joint arthroplasty from distal extremity sepsis.

At the UCLA Medical Center in three patients treated for hematogenous infection after total joint arthroplasty, the source was apparently an infection in the extremities at a site distal to the joint arthroplasty. In a 72-year-old woman with rheumatoid arthritis infection developed in the right hip after total hip arthroplasty following a Staphylococcus aureus infection at the site of a left metatarsophalangeal arthroplasty. In a 64-year-old man with osteoarthritis the staphylococcal infection that developed after right total hip arthroplasty was seeded from a pyarthrosis of the right knee. In a 61-year-old woman with rheumatoid arthritis the sites of bilateral knee arthroplasties were seeded from a soft tissue infection of the left foot. These cases illustrate the potential for infection from local wound sepsis distal to joint arthroplasty. Such infections, particularly in patients with rheumatoid arthritis, should be treated aggressively to avoid seeding of the more proximal total joint arthroplasty site.

The effect of tibia-foot rotatory position on the anterior drawer test.

The effect of the position of the foot and tibia on the anteroposterior drawer test was quantified using a clinical testing device. Maximum laxity occurred at 15 degrees of external rotation of the foot. Extreme rotation of the foot and tibia resulted in reductions of anteroposterior laxity of 63% for internal rotation and 50% for external rotation. The ratio of foot rotation to tibia rotation was approximately 2:1. Medial meniscectomy alone did not result in increased anteroposterior laxities when compared with normal knees. Medial meniscectomy with an unrepaired anterior cruciate ligament tear resulted in increased anteroposterior laxities at 15 degrees, 30 degrees, and maximum external rotation of the foot.

The acetabular cement-bone interface in experimental arthroplasties in dogs.

Increased clinical loosening of total hip arthroplasty acetabular components has been noted in patients with long follow-up and in young active individuals. Evaluation of the acetabular cement-bone interface has been limited to a few human cadaveric specimens and to canine studies in which the data are difficult to interpret. The effects of cement fixation of the acetabular component were investigated in serial observations in 21 dogs with hip surface replacements. The postoperative survival time before evaluation was from two to 46 weeks. Twenty animals were clinically normal before autopsy. Analytic techniques used to examine acetabular fixation included the use of epoxy-embedded specimens to preserve the cement-bone interface and conventional histologic sections. After two weeks, no direct contact between the cement and bone was seen. A correlation between the adequacy of cement fixation and interface membrane thickness was found. Poor acrylic fixation resulted in thick membranes up to 2 mm thick and horizontal trabeculation of the interface woven bone. Good cement intrusion led to a thinner, almost minimal membrane two to three cells in thickness.

In vivo stability testing of post-meniscectomy knees.

Post-meniscectomy knees examined with an instrumented clinical testing device reveal that meniscectomy alone does not cause a measurable degree of instability. If meniscectomy causes a minor degree of instability, the degree is within the right-left variation for a normal population. Medical meniscectomy in combination with a torn anterior cruciate results in an increased anterior-posterior instability at 20 degrees knee flexion. The device used in this study was more reliable in diagnosing increased anterior-posterior instability secondary to anterior-cruciate tear than was a clinical examiner.