[Modern unicondylar knee arthroplasty. Tips and tricks]. / Moderne unikondyläre Kniearthroplastik. Tipps und Tricks.

BACKGROUND: Unicondylar knee arthroplasty (UKA) is an established therapeutic option for advanced medial or lateral gonarthrosis. OBJECTIVES: The cornerstones of a successful UKA, careful patient selection, preoperative planning and precise operation technique, are discussed in this overview article. IMPORTANCE: In contrast to total knee arthroplasty, UKA allows preservation of the contralateral and patellofemoral compartments as well as the cruciate ligaments and is often associated with rapid postoperative recovery, improved knee kinematics and knee function. However, UKA is technically very demanding. High revision rates have been reported in particular with widespread application, according to national joint replacement registries. CONCLUSION: Successful UKA relies on meticulous patient selection, preoperative planning and surgical technique. It is justified to broaden classic UKA indications. In medial and lateral UKA three types of mechanical varus-valgus deformity can be encountered: type 1 (isolated intraarticular deformity), type 2 (pronounced deformity due to extraarticular varus deformity in medial UKA or valgus deformity in lateral UKA), type 3 (reduced deformity due to extraarticular valgus deformity in medial UKA or varus deformity in lateral UKA). We believe these deformities should be addressed accordingly with surgical technique.

The 12-item Oxford Knee Score: cross-cultural adaptation into German and assessment of its psychometric properties in patients with osteoarthritis of the knee.

OBJECTIVE: To cross-culturally adapt and validate the Oxford Knee Score (OKS) for use in German-speaking patients with osteoarthritis of the knee. METHODS: After the cross-cultural adaptation (OKS-D), the following metric properties of the questionnaire were assessed in 100 consecutive patients (mean age 66.5 years, 61 women) undergoing total knee replacement: feasibility (percentage of fully completed questionnaires), reliability (Intraclass Correlation Coefficients [ICC] and Bland and Altman's limits of agreement), and construct validity (correlation with the Western Ontario and McMaster Universities Index [WOMAC], Knee Society Score [KSS], Activities of Daily Living Scale [ADLS], and Short Form 12 [SF-12]), floor and ceiling effects, and internal consistency (Cronbach's Alpha, CA). RESULTS: We received 91.9% fully completed questionnaires. Reliability of the OKS-D was excellent (ICC 0.91). Bland and Altman's limits of agreement revealed no significant bias (-0.2) and a random error of 6.2. Correlation coefficients with the other questionnaires ranged from -0.22 (SF-12 Mental Component Scale [MCS]) to -0.77 (ADLS). We observed no floor or ceiling effects. The CA was 0.83. CONCLUSIONS: The German version of the OKS is a reliable and valid measure for the self-assessment of pain and function in German-speaking patients with osteoarthritis of the knee.

Femoral component rotation in mobile-bearing total knee arthroplasty.

The surgical technique utilized for the LCS mobile-bearing since 1977 has been a tibial cut first method which requires determination of femoral rotation with tension spacing. We evaluated 38 randomly selected mobile-bearing TKA in which this technique was utilized. All cases had satisfactory clinical results. Spiral computed tomography scans measured the posterior condylar angle which is the angle of the femoral component posterior condyles in relation to the surgical transepicondylar axis. The mean femoral component alignment was 0.3 degrees of internal rotation to the transepicondylar axis (S.D.=2.2 degrees ; range=6 degrees internal to 4 degrees external). Four cases (10%) were outside of 3 degrees from the TEA. Lateral patellar tilt and subluxation was identified in one female who had a femoral component position of 5 degrees internal rotation. In 90% of cases, the posterior condylar angle was within 3 degrees of the surgical transepicondylar axis which is regarded as the functional ideal for conventional methods.

Femoral component rotation and arthrofibrosis following mobile-bearing total knee arthroplasty.

The purpose of this study was to evaluate the femoral component rotation in a small subset of patients who had developed arthrofibrosis after mobile-bearing total knee arthroplasty (TKA). Arthrofibrosis was defined as flexion less than 90 degrees or a flexion contracture greater than 10 degrees following TKA. From a consecutive cohort of 3,058 mobile-bearing TKAs, 49 (1.6%) patients were diagnosed as having arthrofibrosis, of which 38 (86%) could be recruited for clinical assessment. Femoral rotation of a control group of 38 asymptomatic TKA patients matched for age, gender, and body mass index was also evaluated. The surgical epicondylar axis was compared with the posterior condylar axis for the femoral prosthesis. Femoral components in the arthrofibrosis group were significantly internally rotated by a mean of 4.7 degrees (SD 2.2 degrees , range 10 degrees internal to 1 degrees external). In the control group, the femoral component had a mean 0.3 degrees internal rotation (SD 2.3 degrees , range 4 degrees internal to 6 degrees external). Following mobile-bearing TKA, there is a significant correlation between internal femoral component rotation and chronic arthrofibrosis.

[Rehabilitation guidelines after total knee arthroplasty]. / Rehabilitationsrichtlinien nach Knieendoprothesen.

Rehabilitation programs after total knee arthroplasty vary as much as do the surgical procedures employed. The postoperative range of motion of the knee is considered to be one of the primary indicators of the success of arthroplasty surgery. Protocols focusing on improving range of motion have been widely investigated: the end result does not seem to depend on using specific devices or exercises. There are no prospective randomized clinical trials evaluating the differences in outcome after total knee arthroplasty between patients following different rehabilitation programs. What are the needs of the patient after this surgery? Rehabilitation should focus on physical and functional limitations, and guidance of the patient during this process is important. The patient follows an individual program comprising a sensorimotor progression in weight-bearing positions to allow for improved functional knee stabilization. In knee osteoarthritis, and also after total knee arthroplasty, the neuromuscular system undergoes various adaptations during gait and other activities. Because of this, rehabilitation should not attempt to achieve hypothetical norms, but to help the patient in the motor learning process of acquiring improved motion patterns and stabilization strategies.

Total knee arthroplasty after formal knee fusion using unconstrained and semiconstrained components: a report of 7 cases.

Seven cases of total knee arthroplasty (TKA) after formal knee fusion were reviewed at a mean follow-up of 56 months (range, 12-161 months). The mean modified Hospital for Special Surgery score improved from 54 (range, 16-65) preoperatively to 68 (range, 57-80) at the latest follow-up. Mean range of motion was 74 degrees (range, 55-90 degrees ). Patient subjective rating was excellent or satisfied in 5 of 7 cases. Two patients underwent secondary refusion (1 for chronic infection, 1 for ligamentous instability). Six patients (86%) had to undergo reoperation for postoperative complications: 3 patients had open arthrolysis for adhesion and arthrofibrosis, 2 patients had a gastrocnemius flap for skin necrosis, and 1 patient had neurolysis of the peroneal nerve for painful paresis. Despite the presence of increased postoperative pain while walking, all 5 patients with the TKA still in place declared that they would undergo the same procedure again. The procedure of TKA in fused knees is technically demanding and has a considerable complication rate. Renewed mobility of the fused knee joint appears to correlate with increased pain on walking in this group of patients. Four types of postoperative problems were noted in the evaluation: skin necrosis, extensor mechanism contracture, insufficient collateral ligaments, and adhesion and arthrofibrosis. Takedown of a formal knee fusion with TKA should be performed only in carefully selected cases and in highly motivated patients with realistic expectations.

Arthroscopic partial meniscectomy in patients over 70 years of age.

PURPOSE: This study was conducted to determine the importance of age as a limiting factor as well as to assess the role of age in combination with cartilage damage or osteoarthritis as predicting factors for the outcome after arthroscopic partial meniscectomy. TYPE OF STUDY: Case series. METHODS: We reviewed 97 patients over 70 years of age who underwent an arthroscopic partial meniscectomy between 1992 and 1996. At the time of evaluation, 5 patients had died and 1 patient was unavailable, leaving 91 patients (95 knees) suitable for assessment. There were 56 women and 35 men. The average age at time of surgery was 74 years (range, 70 to 84 years). The mean follow-up period was 4 years (range, 2 to 6 years). Assessment of the cases by 1 investigator included medical records and preoperative radiographs of the knee joint, with the main interest focused on evidence of osteoarthritis using the classification of Kellgren and Lawrence. Evaluation of cartilage damage was performed on surgical videotapes according to Outerbridge. All 91 patients were personally interviewed by telephone. The questionnaire included influence of the operation on knee pain, quality and duration of satisfaction, requirement of further surgery, and whether the patient would undergo the same operation again. RESULTS: According to the Kellgren and Lawrence classification, 80% of patients had radiographic evidence of osteoarthritis grade 0-2, and 20% had grade 3-4. According to Outerbridge, 43% of the patients had cartilage damage grade 0-2 and 57% had grade 3-4; 81% of the patients with osteoarthritis grade 0-2 and 83% of the patients with cartilage damage grade 0-2 had a satisfactory outcome when followed-up for more than 2 years. Among the patients with osteoarthritis grade 3-4 or cartilage damage grade 3-4, 55% and 69%, respectively, were satisfied when followed-up for more than 2 years; 45% and 37%, respectively, required a further surgery after 1 to 4 years. The grade of osteoarthritis had significant influence on satisfaction (P <.01), on whether the patients would have the operation done again (P =.01), and on whether they required further surgery (P =.04). The severity of cartilage damage only had a significant influence on whether the patients would undergo the operation again (P =.01). CONCLUSIONS: Pre-existing degenerative changes appeared to affect the outcome more than the patient's age. However, arthroscopic partial meniscectomy was followed by satisfactory results in more than two thirds of our cases even if performed in the presence of moderate degenerative changes. But two thirds does not correspond with the good results usually obtained in a younger population. Therefore, the indication for surgery and the expected outcome have to be evaluated carefully in elderly patients.

[Intermediate term outcome of of a hip prosthesis revision system]. / Mittelfristige Ergebnisse mit einem Hüftschaftrevisionssystem.

The Zweymüller shaft for uncemented total hip arthroplasty was developed in the early 1970s. Encouraged by the clinical results with this stem, which was mainly used in primary arthroplasty, longer fitting stems were added to the line to accommodate bony defects and to allow for an optimal load transfer from proximal to distal. The principal of the design is to allow an optimal distal fixation while allowing the bone to remodel in the proximal part. This study reports on 89 patients who underwent revision surgery of the hip for mostly aseptic loosening. The results after a median follow-up of 36 months show an increase of the modified Harris hip score from 52 points pre- to 82 points postoperatively. Radiographic subsidence was found in nine cases, with eight having progressed for more then 3 mm. Postoperative complications occurred in 11.2%, with seven dislocations. Open revision became necessary in two cases. The stem reviewed here seems to achieve predictable results in cases where a proximal cone is still present to facilitate load transfer, while at the same time the quadrangular stem provides solid distal fixation and ensures rotary stability.

Patella resurfacing in total knee arthroplasty using metal-backed rotating bearing components: a 2- to 10-year follow-up evaluation.

Management of the patella in total knee arthroplasty (TKA) has become an important issue. Patella-related complications remain a major concern and have frequently been the reason for secondary intervention, whether resurfaced or not. Common modes of failures are increased polyethylene (PE) wear, PE fractures, component dissociation (loosening or PE spinout), and patella fractures. This study evaluated 235 cases of low contact stress (LCS) TKA using a metal-backed rotating PE bearing. The setting was a large joint replacement center which has performed more than 2750 cases of LCS TKA since 1988. Cases with a follow-up shorter than 2 years were not calculated for statistical analysis but were included in postoperative complications. The mean follow-up was 4.2 years (range 2-10 years). Of the 105 cases 94.7% scored excellent or good results on a modified 100-point Hospital for Special Surgery score. Patellofemoral tracking was analyzed on axial radiographs in all cases and revealed perfect tracking in 96%. Revision surgery related to patella complications was required in 7 of 235 cases (3%), including two of PE bearing spinout and one each of infection, patella necrosis, PE break-age, patella maltracking, and traumatic patella component loosening. Four patella complications (1.7%) were related to patellofemoral maltracking, excluding the infected, traumatic, and patella necrosis cases. These results are similar to or better than those reported in the literature and complications appear to occur more frequently in cases with non-ideal patellofemoral maltracking.

Total knee arthroplasty in a patient with chronic occlusion of the superficial femoral artery.

In a 67-year-old patient with severe valgus gonarthrosis and chronic occlusion of the superficial femoral artery on the same side, total knee replacement was performed without preceding angioplasty because the collateral circulation was intact. No tourniquet was used. To leave the peripatellar arterial ring intact on one side in this case of lateral patellar maltracking, a lateral approach was used. In this approach, a lateral release forms part of the approach itself. To achieve gentle eversion of the patella, the tibial tubercle was osteotomized. One year postoperatively, the patient was satisfied with the outcome and showed no clinical signs of any vascular deterioration. It is concluded that total knee replacement may be possible in the presence of chronic occlusion of the superficial femoral artery provided that the collateral circulation is intact.

Quality assurance in hip arthroplasty.

Documentation is key to quality assurance (QA): Data must be complete, plausible, and comparable, and then analyzed to implement corrective measures. Important factors are: qualification of care-providing staff, equipment and implants available (structural quality), effective scheduling of operations and therapy management (process quality), and patient status monitoring (outcome quality). The primary aim is to reveal deficits in process quality and develop and implement improvements in care. QA does not aim at exposing individual mistakes or flawed techniques; rather it is designed to analyze processes and treatments and implement specific solutions. An evaluation profile with the key quality indicators and a QA guideline is presented. A survey conducted in Germany, Austria, and Switzerland revealed: (1) up to 12-month waiting period for surgery in 6%, (2) only 40% written instructions, (3) data mostly written by hand, (4) differences in surgery planning and use of prosthesis passport, (6) inconsistent data analysis, (7) corrective measures rarely implemented.

Lateral approach with osteotomy of the tibial tubercle in primary total knee arthroplasty.

In a prospective study of 51 patients (61 cases) with primary total knee arthroplasty (valgus knees and/or knees that had undergone previous nonarthroplasty surgery), a lateral approach with osteotomy of the tibial tubercle was performed. In a lateral approach, lateral release techniques form part of the approach. In addition, the medial blood supply to the patella is preserved. An additional tibial osteotomy grants wide exposure with little tension on the extensor mechanism during eversion of the patella. The patients were followed up clinically (51 patients, 61 cases) and radiologically (44 patients, 52 cases) for 1 year. No postoperative tibial fractures, no delayed unions, and no nonunions at the site of the osteotomy were seen. No patellar necrosis occurred. The results after 1 year were good or excellent in 45 (88%) patients, fair in four (8%), and poor in two (4%). Complications related to technique were hematoma (four patients) and compartment syndrome (one patient). These complications occurred early in the series and were eliminated by technical modifications.

Uncemented total hip arthroplasty in patients with rheumatoid arthritis.

Total hip arthroplasty has become a successful way of treating the painful and destroyed hip joint in the patient with rheumatoid arthritis. Because of the underlying disease, it still is controversial whether the implants selected should be used with bone cement, or whether uncemented devices will give equally good results in this population. Fifteen patients suffering from rheumatoid arthritis underwent 21 hip arthroplasties. The followup period averaged 3.3 years (range, 2.5-6.8 years). All but one patient were taking medication at the time of surgery for their underlying disease. Clinical evaluation was based on a modified Harris hip score that showed significant improvement in pain and function preoperatively compared with pain and function at the most recent followup. Radiographic analysis revealed five cases of minor migration of the acetabular components, and three cases of distal migration of 2 mm or less in the femoral components. Complications consisted of heterotopic ossifications in one patient, and an intraoperative femoral fracture in one patient. There were no infections, and there were no deep vein thromboses. The results in these patients suggest that cementless total hip arthroplasty might become a successful way of treating the destroyed hip joint in the patient with rheumatoid arthritis.

[Quality assurance in endoprosthetics]. / Qualitätssicherung in der Endoprothetik.

BACKGROUND: To evaluate the level of documentation as an instrument of ongoing quality management in arthroplasty, a questionnaire was created on this subject, which concentrated on structural and process indicators. METHODS: A total of 908 questionnaires was sent to orthopedic and trauma departments in Austria, Germany and Switzerland and were evaluated anonymously. RESULTS: The quota of return was 54% in Switzerland, 47% in Austria and 25% in Germany. The waiting period for an arthroplasty is much less in Switzerland and in Germany than in Austria. Only 40% of patients receive forms for informed consent. Documentation is seldomly standardized thus making comparison virtually impossible. Surgical planning is usually done with templates in Germany and Austria, in Switzerland with drawings. Prosthesis passports are predominately used by orthopedic departments. The data regarding complication rates and infections are not analyzed at regular intervals (max. 30%) and corrective measures are rarely implemented. CONCLUSION: Documentation is the basic instrument of quality management and requires completeness (totality) and plausibility of the datas. It is of great importance that evaluated data are analyzed and consequences are taken. The primary aim of quality assurance is to identify problems that adversely affect quality in order to develop and implement process sequences for the improvement of patient care and management.

Quantitative gait analysis after bilateral total knee arthroplasty with two different systems within each subject.

The functional behavior of two kinematically different knee arthroplasty systems within each subject was studied by gait analysis (three-dimensional kinematics, kinetics, dynamic electromyography) in five elderly patients, 2 to 5 years after bilateral surgery. Clinical results were good, yet gait velocity was reduced (range, 0.57-1.1 m/s), with a shortened stride length and a decreased duration of single-limb stance in all subjects. Force plate recordings revealed an undynamic gait with slow loading, reduced modulation of the vertical forces, and poor fore/aft shears. Sagittal plane knee motion during gait was reduced in all subjects, with trunk and pelvic compensation patterns for foot clearance. Muscle activity around the knee was prolonged bilaterally, with activity modulation related to the motion pattern. Although the stride parameters were quite symmetric, there was a marked asymmetry of the motion pattern, with a side-to-side difference of peak knee flexion during stance and swing phase of up to 15 degrees. This finding, however, was not clearly related to the type of prosthesis. Even within one subject, significant side-to-side variability may persist, which leads to asymmetry of the motion pattern, unrelated to the kinematic design of the implant. Other factors, such as the patella-extensor mechanism, ligament balancing, leg-length discrepancy, proprioception, continuation of a preoperative habit, or a contralateral influence, may explain part of the asymmetry seen in these subjects.

Complications in hip arthroscopy.

Hip arthroscopy is being recognized as a valuable additional procedure in the treatment of disorders of this joint. Although initially employed as a diagnostic tool only, better understanding of the anatomy involved and advanced skills have now made surgical treatment possible. Because the techniques are still evolving, a standardized approach is just being established. Little is known on possible complications associated with the procedure, concentrating in most cases on the neurovascular structures at risk during instrument introduction. This study reports on 19 patients in whom three complications were encountered. Two were attributable to positioning problems of the patients, and one was caused by intraoperative extravasation of irrigation fluids. The available literature on complications in hip arthroscopy is being reviewed, and the prevention of complications as experienced in this series is being discussed.

[2-stage exchange in the treatment of infected knee prosthesis]. / Der zweizeitige Wechsel bei der Behandlung der infizierten Knieprothese.

We report our experience with the treatment of infected total knee arthroplasties with a two-stage procedure during the period between 1992 and 1995. The two-stage procedure as a cure for infected total knee arthroplasty is a reliable and reproducible method of treatment. The infection healed in 86% of cases, and all patients with a follow-up of more than 1 year were satisfied with the result achieved. Also the objective values proved that the outcome of this severe complication of total knee arthroplasty was favorable. The two-stage exchange procedure is recommended as the treatment of choice for infected total knee arthroplasty wherever possible.

[Knee joint arthroscopy in the growth years]. / Die Kniegelenkarthroskopie im Wachstumsalter.

An increasing number of children and adolescents are complaining about knee pain. Because of unspecific patient history and the difficulty of clinical examination a correct diagnosis can be made in only half of the patients. The importance of the diagnostic and therapeutic knee arthroscopy has therefore increased. Indication, technique, complications and results are discussed.