Early failures in total knee arthroplasty.

Total knee arthroplasty is a predictable operation. Unfortunately, there is a subset of patients who do not do well and require revision surgery within the first 5 years. The purpose of the current study was to analyze the mechanisms of failure in patients who had revision surgery within 5 years of their index arthroplasty. Between 1986 and 1999, 440 patients with total knee arthroplasties were referred for revision surgery. An analysis of patients in whom the arthroplasties failed within 5 years of the index arthroplasty and the reasons for early failure were documented. Of the 440 patients who had revision surgery, 279 (63%) had revision surgery within 5 years of their index arthroplasty: 105 of the 279 patients with early failures (38%) had revision surgery because of infection; 74 (27%) had revision surgery because of instability; 37 (13%) had revision surgery because of failure of ingrowth of a porous-coated implant; 22 (8%) had revision surgery because of patellofemoral problems; and 21 (7%) had revision surgery because of wear or osteolysis. Only eight of the 279 patients with early failures (3%) had revision surgery because of aseptic loosening of a cemented implant. The remaining 12 patients had revision surgery because of miscellaneous problems. Host factors may prevent infection from ever being eradicated totally. The two other major patterns of failure in this series were failure of cementless fixation and instability. If all of the arthroplasties in the patients in this early failure group would have been cemented routinely and balanced carefully, the total number of early revisions would have decreased by approximately 40%, and the overall failures would have been reduced by 25%.

Articulating versus static spacers in revision total knee arthroplasty for sepsis. The Ranawat Award.

Antibiotic laden spacer blocks frequently are used to treat an infected total knee arthroplasty. Static spacer blocks make exposure at reimplantation difficult secondary to quadriceps shortening. Unexpected bone loss attributable to migration of the spacer block also has been reported. To avoid these problems, a temporary articulating molded implant made of antibiotic cement was used in a consecutive series. The authors sought to determine whether its use would affect the reinfection rate, improve functional results, or prevent bone loss compared with static spacers. Twenty-five patients were treated with static nonarticulating spacers. Since 1996, 30 patients have been treated with tobramycin-laden articulating spacers. The knee arthroplasties in three patients treated with a static spacer became reinfected (12%). The knee arthroplasty in one patient with an articulating spacer became reinfected (7%). Fifteen of the 25 patients with static spacers had unexpected bone loss between stages. No appreciable bone loss could be measured in the patients who received articulating spacers. The average Hospital for Special Surgery score was 83 points in the patients with static spacers and 84 points for the patients with articulating spacers. Range of motion at final followup averaged 98 degrees in the patients who received static spacers and 105 degrees in the patients who received articulating spacers. Articulating spacers seem to facilitate reimplantation of infected total knee arthroplasty without additional risk of infection. Unexpected bone loss is no longer a concern with this two-stage technique. Articulating spacers offered no functional advantage over static spacers in this study group.

Rotational malalignment of the femoral component in total knee arthroplasty.

Ligamentous balancing is a crucial part of total knee arthroplasty. To ensure proper kinematics, balance must be achieved in flexion and extension. Failure to do so may result in limited range of motion, premature polyethylene wear, or patellofemoral tracking problems. Balancing in extension is dependent on the type and extent of correctional ligamentous release. Flexion balance is dependent on proper femoral rotation. There are two methods to determine femoral rotation. In the classic method, the knee is tensed in flexion after ligamentous release in extension. The anteroposterior cut then is made parallel to the cut tibial surface. Alternatively, the anteroposterior cut can be based off fixed femoral landmarks. The purpose of the current study was to determine the variance between balancing the flexion gap with the classic method versus the technique of using fixed femoral landmarks to determine rotation. One hundred consecutive posterior stabilized knee arthroplasties were performed using the classic method. The resected posterior condyles in each case were measured. The actual difference between the resected condyles using the classic method was compared with the calculated difference of resected bone using bony landmarks to determine rotation. A variance analysis then was performed. Compared with classically balanced knees, rotational errors of at least 3 degrees occurred in 45 % of patients when rotation was determined from fixed bony landmarks. These patients had trapezoidal rather than rectangular flexion gaps. Such errors may have implications regarding polyethylene wear, range of motion, and long-term clinical results.

Underestimation of pelvic osteolysis: the value of the iliac oblique radiograph.

Periacetabular osteolysis is recognized as a complication of cementless total hip arthroplasty. Routine follow-up radiographs are recommended by most joint reconstructive surgeons to detect osteolytic lesions that may remain asymptomatic. These studies usually consist of an anteroposterior (AP) pelvic and lateral radiograph of the hip. Three male cadaver pelves were used to evaluate whether a routine AP pelvic radiograph was adequate to show certain osteolytic lesions. This study involved creation of progressively enlarging defects simulating an osteolytic lesion of the posterior wall. The extent of involvement of the lesion as shown by an AP pelvic radiograph and iliac oblique views was then compared. By the time the posterior column lesion could be estimated to the same extent on both the AP pelvic and iliac oblique radiographs, the lesion had become uncontained in the posterior medial direction. The evaluation of pelvic osteolysis with biplanar imaging provides a 3-dimensional understanding of the lesion. This study shows the inadequacy of a single AP pelvic radiograph in showing and localizing periprosthetic osteolytic lesions in the posterior column.

Motion at the modular acetabular shell and liner interface. A comparative study.

Excessive polyethylene debris generated from a total hip arthroplasty can lead to osteolysis and premature revision. Most of this polyethylene debris comes from the concave articulation. However, abrasive wear on the convex side of a modular polyethylene component also may play a role in this problem. Motion of a modular polyethylene liner with respect to its shell can lead to such abrasive wear. Six samples of modular acetabular components from eight manufacturers were tested for motion between the shell and the liner. Motion at the shell liner interface was detected by five fiberoptic sensors in the x, y, and z planes. Micromotion occurred at the shell liner interface in all designs tested. The magnitude of motion varied between manufacturers, ranging from 5 to 311 microns. Design features that limit motion may be advantageous in limiting the amount of polyethylene debris.

Cementless fixation in 2-stage reimplantation for periprosthetic sepsis.

Twenty-five patients with documented infection of the hip were reviewed. All patients underwent reconstruction in a 2-stage fashion with cementless implants. The average follow-up in this group was 41 months. The average time to reimplantation was 4.8 months. Of the 25 living patients, 22 retained their implants. There were 2 recurrences of infection, for an infection recurrence rate of 8% (2 of 25). The average postoperative Harris Hip Score was 81. Bone ingrowth was confirmed radiographically via the Engh fixation score in all but 1 of the surviving implants. Cementless fixation in 2-stage reimplantation can result in acceptable eradication rates, while supplying predictable fixation, provided that appropriate cementless revision implants are used.

Revision of failed cementless total knee implants with cement.

Between 1986 and 1996, 268 revision total knee replacements were performed. Revisions for aseptic loosening were reviewed prospectively. Sixty-three patients had implants revised for aseptic loosening. Thirty-six of the patients had revisions of cemented constructs, whereas 27 of the patients had revisions of cementless constructs. The average time before revision for the cemented group was 86 months. The average time to revision for the cementless group was only 43 months. Fifty-two percent of the patients in the cementless group had revision of their implants within 2 years of their index arthroplasty. The average pain free interval for the cementless group was only 11 months with 63% of the patients having no pain relief after their index arthroplasty. The average postoperative score for the cementless group was 88, whereas the average postoperative score for the cemented group was 82. Revision of failed cementless total knee implants with cement is a reliable procedure. Results are similar to those of cemented knees revised with cement.

Bone loss associated with the use of spacer blocks in infected total knee arthroplasty.

Twenty-five knees in 24 patients with infected total knee replacements were treated with debridement, component removal, and insertion of an antibiotic impregnated cement spacer block. Intravenous antibiotics were administered for 6 weeks during which time the patients' knees were kept in a knee immobilizer nonweightbearing. These cases were reviewed retrospectively to determine radiographically the amount of bone loss that occurred during the period before reimplantation. Tibial and femoral bone loss occurred frequently from invagination of the cement spacer block into the femoral and tibial cancellous bone. Tibial bone loss was present in 10 (40%) cases and averaged 6.2 mm. Femoral bone loss was present in 11 (44%) cases and averaged 12.8 mm. Bone loss was more common when spacer blocks were undersized. None of the 15 spacer blocks that were made with a small intramedullary stem displaced. Three of the remaining 10 spacer blocks made without an intramedullary stem did displace with associated bone loss. Antibiotic spacer blocks used in the two-stage treatment of infected total knee replacements can be associated with subsequent tibial and femoral bone loss.

Fluoroscopic evaluation of the painful total knee arthroplasty.

Results of total knee arthroplasty are uniformly good. There is, however, a certain subset of patients who, despite an excellent radiographic result, do not do well. From 1992 through 1994, 20 patients were referred for pain and disability after total knee arthroplasty with normal appearing office radiographs. Fluoroscopic radiographs were obtained after other causes of disability were excluded. In 14 of the 20 patients, the diagnosis of aseptic loosening was made with fluoroscopically guided radiographs. Each patient thought to have a loose component at fluoroscopy did, in fact, have a loose component at revision. Each patient improved after revision with an average increase in the Hospital for Special Surgery score of 26 points. Fluoroscopically guided radiographs can be helpful in evaluating the patient with a painful total knee arthroplasty and normal appearing office radiographs.

Aspiration as a guide to sepsis in revision total hip arthroplasty.

One hundred sixty-five patients underwent 171 preoperative aspiration arthrograms to evaluate a painful total hip arthroplasty. Intraoperative cultures and histologic specimens were obtained in all cases. Of the 166 aspirations where fluid was obtained, there were 140 true negative, 5 true positive, 18 false positive, and 3 false negative cultures. Sensitivity of hip aspiration to identify periprosthetic sepsis correctly was 50%; specificity was 88%. Hip aspiration with a 50% sensitivity rate lacks the ability to consistently predict those patients with occult periprosthetic sepsis. The routine use of aspiration in evaluation of a painful total hip is probably not indicated. Selective use in patients with a history of wound healing problems, radiographic changes, and elevated laboratory values should be considered.

Modular tibial augmentations in total knee arthroplasty.

Proximal tibial bony deficiencies are not uncommon in primary and revision total knee arthroplasty. Modular tibial augmentations were introduced to address these deficiencies. Alterations in strain distribution as a result of medial wedge and block augmentations were evaluated for a modular total knee arthroplasty system in 6 fresh frozen anatomic specimen tibias. Full-field strain patterns were examined using photoelastic coating methods, and high strain regions were evaluated using strain gage rosette techniques. The total knee arthroplasty installations were tested in static physiologic axial and torsional load configurations. The relative effects of sequential wedge and block augmentations compared with the nonaugmented case were statistically analyzed. There were no overall statistical differences in the 3 treatments in terms of maximal (principal) strains. A secondary analysis that evaluated specific location and load pattern combinations established several minor statistical differences along with insights into the manner in which each construct loads the proximal tibia. Although metal wedge augmentation commonly is used, block augmentation seems to be an appropriate alternative from a strain distribution standpoint in cases in which the block geometry better approximates the bony defect.

Core decompression of the osteonecrotic femoral head.

The results in 114 hips of ninety-two patients who had osteonecrosis of the femoral head were assessed after treatment with core decompression. The average duration of follow-up was three years and four months (range, two years to six years and six months). The average age of the patients was forty-one years (range, fifteen to sixty-seven years). The presumed risk factors were the use of corticosteroids (thirty-seven hips), excessive use of alcohol (thirty-two hips), trauma (seven hips), and various other factors (seven hips). No specific risk factor was identified for thirty-one hips, and the osteonecrosis was considered to be idiopathic. The preoperative evaluation consisted of clinical assessment, magnetic resonance imaging, and radiographic staging according to a modification of the system of Ficat. Thirty-two hips were in stage I; thirty-eight, in stage IIA; twenty-five, in stage IIB (transition stage, with a crescent sign); and nineteen, in stage III. Clinical failure was defined as the performance of a subsequent operation. Over-all, sixty-four hips (56 percent) failed clinically. Fifty-seven were treated with a hip replacement; four, with a femoral osteotomy; and three, with a vascularized fibular graft. Clinical failure was seen in five (16 percent) of the thirty-two hips in stage I, twenty (53 percent) of the thirty-eight hips in stage IIA, twenty (80 percent) of the twenty-five hips in stage IIB, and in all nineteen of the hips in stage III.(ABSTRACT TRUNCATED AT 250 WORDS)

Frozen histologic section as a guide to sepsis in revision joint arthroplasty.

The accurate prediction of occult sepsis is very important in evaluating the patient who has a painful prosthetic joint. Unfortunately, there is no single test that is able to consistently differentiate mechanical from septic loosening. Authors have suggested that the presence of acute inflammation on frozen histologic sections correlated well with positive intraoperative cultures. The authors' experience with frozen sections was examined as a guide to the intraoperative determination of occult sepsis in revision joint surgery. One hundred seven consecutive total joint revisions were performed from 1986 to 1989. All patients had a complete histologic analysis of tissue obtained from multiple surgical sites. The relationship between the frozen section, final culture, and complete histologic analysis was evaluated in a comparative fashion. Using a positive culture as the criterion for the presence of occult infection, a statistical analysis comparing frozen sections and the complete histologic analyses were performed. The sensitivity of a frozen section as a diagnostic test to detect occult periprosthetic infection when present was 18.2%. The specificity of a frozen section to correctly identify the absence of infection was 89.5%. The frozen section is a fairly specific, but not a sensitive, screening test for the detection of occult sepsis. Over reliance on this technique in a revision setting should be avoided.

Knee instability after total knee arthroplasty.

From 1986 to the present, 126 total knee revisions were performed by the authors. Twenty-five cases (20%) were revised for instability of the tibiofemoral articulation. Patellofemoral instability and those patients treated conservatively were excluded from this subset of patients. All patients were clinically evaluated using the Hospital for Special Surgery knee rating system and radiographically rated using The Knee Society scoring system. The average follow-up period was 28 months. Preoperative synovial fluid analysis showed a predominance of red blood cells (average, 64,000). Reasons for instability were ligamentous imbalance and incompetence, malalignment and late ligamentous incompetence, a deficient extensor mechanism, inadequate prosthetic design, and surgical error. All patients currently have stable knees with an overall improvement in clinical and radiographic scores. When evaluating a patient with a painful knee after total knee arthroplasty, this diagnosis should be considered. Careful physical examination, dynamic radiographs, and synovial fluid analysis should help to make a proper diagnosis. Treatment should aim to correct the cause of instability. The prosthesis chosen should compensate for the specific ligamentous deficiency present.

Assessment of intrapelvic cement and screws in revision total hip arthroplasty.

Vascular injury resulting from primary and revision hip arthroplasty has been reported to involve both arterial and venous structures. While such complications are extremely uncommon, removal of intrapelvic cement or screws during revision surgery can be hazardous to intrapelvic structures. Both arterial and venous perforations can occur, depending on the level at which the pelvic wall has been breached, and on the orientation of the intruding matter. Complications can be minimized with careful preoperative assessment of pelvic anatomy. Contrast-enhanced computerized tomography scanning can assist the revision surgeon with preoperative planning in those patients requiring removal of intrapelvic components. This technique appears to be an accurate, simple, and noninvasive method by which these intrapelvic relationships may be examined.

Unicondylar arthroplasty. A survivorship analysis.

A retrospective review of 52 cemented unicompartmental arthroplasties was undertaken to determine whether unicompartmental arthroplasty is an acceptable procedure for patients with isolated single-compartment disease. The average follow-up period was 8.3 years with a predicted survivorship of 93.75% at 10 years post-arthroplasty. Results comparable to those for tricompartmental design were achieved at similar follow-up intervals. While stressing the importance of patient selection in this procedure, the authors feel that unicompartmental arthroplasty is a viable alternative to tricompartmental arthroplasty in the treatment of single-compartment disease. Further long-term survivorship analysis is necessary to conclude that unicompartmental results are equal to those of tricompartmental design.

Periprosthetic knee sepsis. The role of irrigation and debridement.

Thirty-three infected total knee arthroplasties were treated by irrigation, debridement, and intravenous antibiotics. These cases were retrospectively reviewed with an average follow-up period of 4.5 years. There were 12 revisions and 21 primary arthroplasties in the series. Thirty-two knees were openly irrigated and debrided, and one was arthroscopically treated. In 20 of 33 knees, infection recurred--a reinfection rate of 61%. The authors attempted to identify factors influencing success and failure of infection eradication. There was a statistically significant improvement in the success rate of knees irrigated and debrided within four weeks of index surgery (p less than .05). No statistically significant correlation was found between success and failure with regard to gender, age, preoperative diagnosis, previous surgery, length of intravenous antibiotics, or time from clinical symptoms to debridement. The authors believe that irrigation and debridement have a role in the immediate postoperative period. Caution should be used in periprosthetic knee infection appearing greater than four weeks from index surgery.

Upper cervical instability in rheumatoid arthritis.

Upper cervical instability remains a significant problem for the patient with rheumatoid arthritis. Seventeen patients treated by upper cervical fusions for instability, were followed to determine the efficacy of our current treatment protocol. Improvement in neurologic status was observed in ten of 11 patients presenting with neurologic symptoms. In all patients with preoperative pain, improvement occurred at least one grade. However, complete amelioration of pain was noted in only five patients. A pseudarthrosis rate of 25% reflects the difficulty in achieving a solid arthrodesis in the patient with rheumatoid disease. Modification of the wedge compression technique may help ensure arthrodesis in rheumatoid patients.

Negative radionuclide scan in osteoid osteoma. A case report.

Advances in radionuclide imaging have facilitated the accurate diagnosis and surgical excision of osteoid osteoma. While radionuclide imaging has been inconsistent in the diagnosis of certain problems, its accuracy in the diagnosis of osteoid osteoma has been frequently stressed. To date, no case of a negative bone scan in the presence of a histologically proven osteoid osteoma has been reported. The present case report emphasizes that a negative bone scan does not preclude the diagnosis of osteoid osteoma. Clinical suspicion remains the most sensitive indicator of this lesion.