The Knee Society Index of Severity for failed total knee arthroplasty: development and validation.

Compared with primary knee replacement, total knee arthroplasty revision surgery is a more complex procedure and accounts for greater expenditures of healthcare resources at each clinical stage. Overall, patients having revision procedures have poorer functional outcomes and higher complication rates than patients having primary arthroplasty. Despite the expanded scope of revision problems and the rapidly emerging technology in revision surgery, the long-term success of any method remains in question. Because there is little consensus on the timing of revision surgery, optimal surgical reconstruction, and the type of prosthesis to be implanted, the Knee Society began development of an Index of Severity for Failed Total Knee Arthroplasty. Fifty-four percent of Knee Society members completed an 82-item questionnaire that determined their clinical impression about potential risk factors for the outcomes of revision surgery for failed total knee replacements. Using these results, a consensus group developed the final version of the index. The result of the nominal group process was the Knee Society Index of Severity, which was based on eight distinct domains. Each domain was divided into attributes and weights based on the questionnaire responses and consensus meeting. Actual case scenarios from five institutions were used to test interrater reliability and validity. The interrater reliability of the average score of all ratings was 0.95; the correlation of the criterion rating with the mean rating was 0.77. When three outliers were not included, the Pearson product correlation increased to 0.92. These data support the application of the Knee Society Index of Severity as a critical component of risk factor studies, effectiveness research, and cost-effectiveness analysis involving revisions of total knee replacements.

The Knee Society Index of Severity for failed total knee arthroplasty: practical application.

Previous classifications of severity for total knee arthroplasty revisions have been based largely on bone loss of the femur and tibia. These approaches failed to address the more technically difficult issues in revision surgery such as surgical exposure, contractures, extremity alignment, implant removal, soft tissue stability (in the anteroposterior and in the sagittal planes), extensor mechanism integrity, and patellar revisability. Through the Knee Society, the authors developed a severity index that incorporated these latter factors into one measure. The current authors describe the application of the Knee Society Index of Severity for failed total knee arthroplasty and its method of scoring.

Use of audiotapes for patient education, medical record documentation, and informed consent in lower extremity reconstruction.

Since 1992, the authors have audiotaped each new patient visit and provided a copy of that tape to the patient. In addition, an office copy of the entire patient interaction is maintained in an office file. One hundred twelve patients seen over a 6-month period participated in a survey measuring their satisfaction with this procedure, and six attorneys were surveyed after listening to a representative tape. Ninety percent of patients had positive comments about receiving the tape. Seventy percent played the tape for others, most commonly their spouses. The attorneys concluded the patient was well served by this process, and there were no increased malpractice issues or exposure. The cost of providing patients with the tapes is minimal, and the high level of patient satisfaction and increased understanding offer a considerable benefit to patients and office staff.

Revision total knee arthroplasty: planning, controversies, and management--infection.

Routine blood work that includes ESR, CRP, and glucose levels, and plain radiographs and knee aspirations are obtained from our patients who have clinical suspicion of infection. If the culture result is positive and blood tests suggest infection, the surgical plan is a two-stage revision with an interval period of intravenous antibiotic administration. Risk factors are identified, and the patient's condition optimized. An infectious disease consultant is also involved in the treatment care plan and advises the patient about the best antibiotic, management of proper antibiotic levels, and home care. If culture results are negative, cultures are repeated every week for 3 to 4 weeks after the patient stops taking antibiotics. If the cultures yield positive results, a two-stage revision protocol is initiated. In patients who have 3 to 4 negative culture results, normal blood tests and radiographs, and no history of any immunocompromised state, such as diabetes or rheumatoid arthritis, diagnoses such as polyethylene wear or synovitis can be considered. If patients have any involved risk factor or blood tests, equivocal or suggestive, isotope scintigraphy is requested. We examine tissue in patients with positive scans and equivocal blood test results with clinical suspicion of infection. We prefer an open arthrotomy, which allows us to take multiple specimens for frozen section, assess fixation of the implant, and look for any other signs of infection. If the frozen section reveals more than 10 PMNLs per high-power field, we proceed to stage 1 revision after obtaining intraoperative cultures. If an organism grows in the cultures, stage 2 protocol is initiated. If no cultures are obtained at 7 to 10 days of incubation, we may consider earlier stage 2 revision at 4 to 6 weeks (Fig. 1). In patients in whom the frozen section reveals less than 5 PMNLs per high-power field, component fixation should be assessed, and if they are loose, revision of the knee should be initiated. As with a septic revision, use of antibiotic-impregnated cement can be considered for fixation. If the components are well fixed, a polyethylene tibial tray is exchanged. In either circumstance, intraoperative cultures should be obtained, and if they yield positive results, antibiotics should be continued for 6 to 12 weeks.

Preoperative planning for lower extremity osteotomies: an analysis using 4 different methods and 3 different osteotomy techniques.

Lower extremity osteotomy is a common procedure for managing deformity and unicompartmental gonarthrosis. One consideration not typically addressed is how the osteotomy will affect the leg length of the extremity. This article presents a numerical analysis of apparent leg-length change before and after osteotomy surgery. It also compares the differences resulting from the 3 different major types of osteotomies (closing wedge, opening wedge, and dome). Three different preoperative planning methods and a fourth intraoperative technique were studied. Using different methods of preoperative planning with the same osteotomy technique resulted in leg-length changes of 0.5 to 3 mm. Differences > 7 degrees in lower extremity alignment may result depending on the planning method used. When comparing osteotomy techniques, 2 cm in leg-length difference was calculated.

The effects of severe femoral bone loss on the flexion extension joint space in revision total knee arthroplasty: a cadaveric analysis and clinical consequences.

Five revision total knee arthroplasties (TKAs) involving severe femoral bone loss were performed in 1994. Each had sufficiently severe femoral bone loss in which collateral ligament origins and posterior capsular attachments were violated. A paradoxical phenomenon was observed in each case. Unlike primary TKAs, in which larger distal femoral bone resection leads to laxity of the knee joint in extension, these cases with severe distal femoral bone loss, after initial component selection, developed the opposite situation, a flexion contracture. It was hypothesized that femoral bone loss involving collateral ligament origins would permit distraction of the tibia below the femur with the knee held in flexion, but when the knee was brought to full extension, intact posterior structures would maintain a normal tibial position. To investigate this hypothesis, six fresh-frozen cadaveric lower limbs were tested in full extension and 45 degrees and 90 degrees of flexion after release of the femoral attachments of the collateral ligaments and the posterior capsule from the femur. Joint space changes were measured via a motion tracking device. Results showed that with loss of collateral attachments, 17.2+/-8.9 mm of joint space is created in 90 degrees of flexion, whereas the joint space in full extension is conserved (1.5+/-1.7 mm). With additional loss of the posterior capsule, the joint space at 90 degrees of flexion increased to 26.2+/-6.1 mm, with minimal changes in the extension gap (3.4+/-0.8 mm). Distal femoral bone loss was associated with an increase in the flexion gap compared to the extension gap.

Total knee arthroplasty ligament balancing and gap kinematics with posterior cruciate ligament retention and sacrifice.

This cadaver study was undertaken to gain insight into the effects that posterior cruciate ligament retention and sacrifice would have on the amount of deformity correction obtained with medial and lateral structure release during total knee arthroplasty. Twenty-seven cadaveric specimens were used to sequentially release medial and lateral structures with and without posterior cruciate support. Each release sequence was tested in full extension and 90 degrees flexion. In full extension, the resulting change into valgus after release of the posterior cruciate ligament, posteromedial capsule/oblique ligament complex, superficial medial collateral ligament, and pes anserinus and semimembranosus tendons was 6.9 degrees, and it increased to 13.4 degrees in 90 degrees flexion. With preservation of the posterior cruciate ligament this decreased to 5.2 degrees in extension and 8.7 degrees in flexion. Changes seen in 90 degrees flexion were significantly greater than those in full extension. For the valgus knee model with release of the posterior cruciate ligament, posterolateral capsule, lateral collateral ligament, iliotibial band, popliteus tendon, and lateral head of the gastrocnemius, 8.9 degrees of change into varus was seen in extension and 18.1 degrees in 90 degrees flexion. With posterior cruciate ligament retention 5.4 degrees and 4.9 degrees of change into varus was seen in extension and flexion, respectively. Significantly less change with retention of the posterior cruciate ligament was seen with both medial and lateral release and more opening of the flexion gap was seen on the release side of the joint for all groups except those with lateral release with sacrifice of the posterior cruciate ligament.

Anatomic and biomechanical aspects of pie crusting posterolateral structures for valgus deformity correction in total knee arthroplasty: a cadaveric study.

Correction of valgus deformity during total knee arthroplasty is usually carried out by releasing lateral supporting structures from the femoral side of the joint. A new technique has been advocated that involves multiple stabs of the scalpel blade or pie crusting of the posterolateral corner. It is the hypothesis of this study that the correction achieved by using this technique occurs when the lateral collateral ligament is effectively released and that the common peroneal nerve may be at risk. Using a cadaveric model with 6 knees tested, significant differences were determined between 2 separate pie crusting steps as well as between releasing the lateral collateral ligament and popliteus tendons. Anatomic dissection studies also showed that in full extension the peroneal nerve may be less than the depth of a number 11 blade (16 mm) from the posterolateral corner, and the nerve may be at risk during this technique. These results show that major deformity correction obtained using the pie crusting technique is probably through effective release of the lateral collateral ligament.

Clinical experience with a proximally porous-coated second-generation cementless total hip prosthesis: minimum 5-year follow-up.

This study reports the minimum 5-year follow-up of our experience with the Porous-Coated Anatomic E (PCA-E) series femoral stem and the modular acetabular cup. A total of 115 consecutive total hip replacements using PCA-E series (Howmedica, Rutherford, NJ) were performed in 108 patients. Six patients whose hips were performing well clinically died before 5-year follow-up and were excluded from the final evaluation. The remaining 109 hips (102 patients) were assessed at a mean follow-up of 72 months (range, 60-84 months). The hip diagnoses were osteoarthritis in 73, osteonecrosis in 31, rheumatoid arthritis in 2, and hip dysplasia in 3. The mean age was 56 years (range, 24-83 years). Three hips were revised: 1 because of late hematogenous infection, 1 because of aseptic loosening of the femoral component, and 1 because of postoperative loosening of an acetabular component. The Harris hip scores improved from a mean of 50 points (range, 20-66 points) preoperatively to a mean of 92 points (range, 64-100 points) at final follow-up. The score differed in each Charnley functional class, with a mean of 93 points (range, 72-100 points) in 57 hips of class A (no other joint involvement); 90 points (range, 58-100 points) in 26 hips of class B (opposite hip involvement); and 85 points (range, 37-100 points) in 26 hips of class C (multiple joint involvement or severe systemic disease). Out of 106 hips that had a full radiographic evaluation performed, 103 femoral components revealed stable bony ingrowth, 2 revealed stable fibrous ingrowth, and 1 showed migration with progressive loosening. This patient with radiographic loosening has minimal symptoms and has not required or been offered further surgery (Harris hip score of 86 points). The low aseptic loosening rate (2%) at minimum 5-year follow-up compares favorably with any cemented or cementless series. The osteolysis that was seen was focal and localized. The short follow-up does not allow determination of progression. There were no cases of distal osteolysis. We attribute the improved results from reported first-generation experience to multiple factors, including increased number of sizes (9 vs 6), increased proportional metaphyseal size, improved polyethylene manufacture (ram extruded vs machined), improved acetabular locking mechanism, and change to 26-mm from 32-mm femoral heads.

Flexion-extension joint gap changes after lateral structure release for valgus deformity correction in total knee arthroplasty: a cadaveric study.

At the time of total knee arthroplasty, the surgeon generally corrects excessive valgus knee alignment to anatomic valgus through release of lateral supporting structures. This study used a cadaveric model to i) study the amount of correction achieved with each release step in 2 sequences of lateral release, ii) compare the amount of release in extension versus flexion, and iii) measure any associated rotational changes of the tibia. Six fresh-frozen cadaveric knees were used to test the amount of change into varus after sectioning the iliotibial band (ITB), the popliteus tendon (Pop), the lateral collateral ligament (LCL), and the tendon of the lateral head of the gastrocnemius (LG). This sequence was then compared with a second sequence in another 6 cadavers as follows: LCL, Pop, ITB, and LG. The amount of valgus correction was tested in 90 degrees, 45 degrees flexion, and full extension. At each flexion angle, the corresponding releases were assessed with the tibia oriented vertically under its own weight, under tibial distraction with equal support from the lateral and medial soft tissues, and under a maximal varus deforming stress. Results showed that complete lateral structure release provides limited correction into a varus direction with a balanced distracted soft tissue gap or extension space (8.9 degrees with the LG released), and the lateral aspect of the flexion gap opens more than the extension gap (8.9 degrees compared with 18.1 degrees in flexion). Early LCL release provided a more uniform release of the joint gap, and rotational changes were variable, tending toward external rotation of the tibia (6.0 degrees in full extension with release of the LCL). We suggest that when severe valgus deformities are present, the LCL should be considered first for release and the Pop and ITB be used to grade the release.

A new technique for determining proper mechanical axis alignment during total knee arthroplasty: progress toward computer-assisted TKA.

Successful total knee arthroplasty (TKA) relies on proper positioning of prosthetic components to restore the mechanical axis of the lower extremity. This report presents and analyzes a new noninvasive method using the Optotrack (Northern Digital Inc, Ontario, Canada) to accurately determine the center of the femoral head. This method, together with direct digitization of the bony landmarks of the knee and ankle intraoperatively, permits placement of the lower extremity in proper alignment intraoperatively. It also permits the surgeon to follow all the angles of movement or rotation and all displacements that occur at each step of the operative procedure. knee intraoperatively via a customized Windows-based program. In addition to presenting our first case, which, importantly, represents the first computer-assisted TKA in a patient, we report on the accuracy and reproducibility of the technique for locating the center of the femoral head obtained during an extensive series of cadaver studies. Location of the femoral head, a major aspect of effecting neutral mechanical axis alignment, appears to be possible to within 2-4 mm, which corresponds to an angular accuracy of better than 1 degree. This method requires no computed tomography scans or other preliminary marker placement. The only basic requirement other than the instrumentation described is a freely mobile hip, which is generally present in TKA patients.

Eliminating patellofemoral complications in total knee arthroplasty: clinical and radiographic results of 121 consecutive cases using the Duracon system.

This study reports the minimum 5-year follow-up of our experience with the Duracon Total Knee Arthroplasty System. A total of 121 consecutive total knee replacements using the Duracon system (Howmedica, Rutherford, NJ) were performed in 104 patients. Three patients died before the 5-year follow-up and were excluded from the final evaluation. The remaining 118 knees (101 patients) were assessed at a mean follow-up of 65 months (range, 60-80 months). The knee diagnoses were osteoarthritis in 97 patients, rheumatoid arthritis in 2 patients, osteonecrosis in 1 patient, and pigmented villonodular synovitis in 1 patient. The mean age was 70 years (range, 28-85 years). There were no reoperations for aseptic loosening, and there have been no reoperations for patellofemoral problems. At final follow-up evaluation, 112 knees (96%) had good or excellent results, and 6 knees (4%) had poor clinical results or went on to revision. For the surviving knees, the preoperative Knee Society objective score improved from a mean of 52 points (range, 20-72 points) to a final follow-up mean of 94 points (range, 66-100 points). Five knees needed reoperations: 2 knees in 1 patient because of acute hematogenous infection at 12 months, 1 knee because of a supracondylar femur fracture, 1 because of a patellar tendon rupture, and 1 to increase polyethylene thickness because of instability. The lack of aseptic loosening at the minimum 5-year follow-up compares favorably with any cemented or cementless series of knee replacement. The almost complete absence of patellofemoral complications in this series also indicates that the design changes, with particular attention to the trochlea design and patellofemoral contact throughout full flexion, have achieved their intended purpose. The results are encouraging at midterm, awaiting true long-term (15-20 years) follow-up.

Posterior cruciate ligament effects on the flexion space in total knee arthroplasty.

Twelve fresh frozen anatomic specimen knees were used in this study to measure changes in the tibiofemoral joint gaps after sacrificing the posterior cruciate ligament. Joint gap changes were measured using a motion tracking device in full extension and at 45 degrees and 90 degrees flexion. Tibiofemoral gaps were measured with no external compressive loads and under tension to define the flexion gap, the space available to be filled by components. After initial anterior cruciate ligament removal, meniscectomy, and a 1-cm tibial plateau cut, sacrifice of the posterior cruciate ligament caused significant differences in the flexion gap. At 90 degrees flexion the tibia distracted from the femur 5.26 +/- 1.9 mm (range, 3.2-9.1 mm) at rest and 6.4 +/- 2.5 mm under tension. No differences in the joint space were calculated in full extension under either loading case. The authors conclude that a major result of posterior cruciate ligament sacrifice is the creation of a larger flexion gap. This result provides insight into relative joint line changes that can occur after posterior cruciate ligament sacrifice. It also suggests the need for greater attention to flexion stability when sacrificing the posterior cruciate ligament and rethinking the role of posterior cruciate ligament release in the management of pure, primary flexion contracture.

The effect of medial release on flexion and extension gaps in cadaveric knees: implications for soft-tissue balancing in total knee arthroplasty.

This cadaver study examined the effects of medial structure release for varus deformity correction during total knee arthroplasty. Twelve specimens were used to investigate the amount of varus correction achieved with sequential release of medial structures. Varus-valgus and internal-external rotation angles were measured using the Isotrack II motion tracking system. Each release sequence was tested at full extension and 45 degrees and 90 degrees of flexion to compare any differences obtained in the joint gaps. After release of the posteromedial capsule oblique ligament complex, superficial medial collateral ligament (MCL), pes anserinus, and semimembranosus tendons, valgus rotation increased to 6.9 degrees in full extension and 13.4 degrees in 90 degrees of flexion. The largest increase (3.2 degrees) in valgus rotation occurred after the superficial MCL was released. Initial release of the superficial MCL led to a more gradual correction with release of subsequent structures. Changes seen in 90 degrees flexion were significantly greater than those in full extension. While the cadaveric model is limited by the lack of deformity in the specimens, the data provide several clinically relevant conclusions. In many cases requiring major medial release for severe varus deformity, potential flexion-extension differences in the resulting tibiofemoral gaps may require new consideration. These data may help explain the heightened interest in and variety of approaches for addressing femoral component rotation and issues of flexion stability since a significantly larger correction is obtained in flexion. Minimal changes in internal-external rotation of the tibia occurred until both the pes anserinus and semimembranosus tendons were released (4 degrees of external rotation).

Surface replacement hemiarthroplasty for the treatment of osteonecrosis of the femoral head.

We reviewed the results of thirty-three femoral resurfacing procedures in twenty-five patients who had stage-III or early stage-IV osteonecrosis of the femoral head according to the classification system of Ficat and Arlet. There were no perioperative complications. Thirty hip prostheses (91 percent) survived for a minimum of five years. At a mean of 10.5 years (range, four to fourteen years) postoperatively, sixteen (62 percent) of the twenty-six hips with stage-III disease had a good or excellent Harris hip score. Four of the seven hips with stage-IV disease did not have or need a total hip arthroplasty. Overall, twenty hips (61 percent) had a good or excellent result according to the scoring system of Harris, and thirteen (39 percent) had a fair or poor result and subsequently had or needed a total hip arthroplasty. The mean interval between the hemiarthroplasty and the total hip arthroplasty was sixty months (range, thirty-six to 136 months). These thirteen hips all had a successful clinical result (a Harris hip score of at least 80 points) at a mean of thirty months (range, twenty-four to seventy-two months) after the total hip arthroplasty. The results of the present study suggest that resurfacing of the femoral head can be a successful interim procedure for the management of patients who have Ficat and Arlet stage-III or early stage-IV disease with a large lesion that is not amenable to other treatment options except total hip arthroplasty.

Total knee arthroplasty in patients receiving Workers' Compensation.

The poor outcomes in patients who have a low-back injury that was sustained while they were on the job have been well described in many studies. The purpose of the current study was to determine the influence of Workers' Compensation on the outcome of total knee arthroplasty in forty-two patients who had been managed between January 1980 and December 1993. There were thirty-two men and ten women, and the mean age at the time of the operation was forty-eight years (range, twenty-nine to sixty-eight years). These patients were directly matched with a group of forty-two patients who were not receiving compensation. The two groups were matched with regard to nine parameters: age, gender, obesity index, preoperative deformity in the coronal plane, preoperative level of symptoms, preoperative radiographic severity according to the criteria of Ahlbäck, method of fixation, number of previous procedures, and duration of follow-up. After a mean duration of follow-up of eighty months (range, forty-eight to 178 months), the patients who were receiving compensation had a mean Knee Society score of 64 points (range, 25 to 100 points). Twelve (29 per cent) of the patients in this group had an excellent or good clinical result, and thirty (71 per cent) had a fair or poor result or had had a revision. The patients who were not receiving compensation had a mean Knee Society score of 93 points (range, 57 to 100 points) after a similar duration of follow-up. Thirty-seven patients (88 per cent) in this group had an excellent or good clinical result, and five (12 per cent) had a fair or poor result or had had a revision; the difference between the two groups with regard to fair or poor results and revisions was significant (p < 0.01). With the numbers available, no significant differences could be detected between the two groups with regard to objective measurements of range of motion and stability or with regard to radiographic alignment, the presence of radiolucent lines, or the shedding of beads. On the basis of our findings, we believe that surgeons should be aware that Workers' Compensation is one of several variables that may have an untoward influence on the perceived outcome of total knee arthroplasty.