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Die massive Streckapparatinsuffizienz ist eine schwerwiegende Komplikation nach totaler Kniearthroplastik. In dieser Ubersichtsarbeit wird die Indikation und detaillierte Operationstechnik der Streckapparatrekonstruktion mit vollstandigem Streckapparat-Allograft behandelt. Die Autoren prasentieren ihre Erfahrungen mit dieser Technik. Jede Form von relevanter Malrotation, Malalignement oder Instabilitat der Knietotalprothese sollte pra- und intraoperativ analysiert und im Rahmen der Streckapparatrekonstruktion korrigiert werden. Eine optimale Wundheilung muss uber eine maximale Allograft-Deckung mit nativem Gewebe sowie einen spannungsfreien Hautverschluss sichergestellt werden. Die stabile Fixation des Allografts distal und die proximale Fixation unter maximalem Zug und bei voller Kniestreckung, geschutzt in einer Knieorthese fur mindestens 8 Wochen postoperativ, sind entscheidend fur den Behandlungserfolg.

Die mediale unikondylare Kniearthroplastik (UKA) ist eine etablierte Behandlungsoption bei fortgeschrittener medialer Gonarthrose. Die Voraussetzungen fur eine erfolgreiche mediale UKA mit fixiertem Polyethylen werden in dieser Ubersichtsarbeit behandelt – sorgfaltige Indikationsstellung, Operationsplanung und prazise Operationstechnik. Im Unterschied zur Knietotalendoprothese erlaubt die UKA den Erhalt des lateralen und patellofemoralen Kompartiments sowie der Kreuzbander und ist oft mit einer rascheren postoperativen Erholung, verbesserten Kniekinematik und Kniefunktion verbunden. Bei Verwendung von UKA mit fixiertem Polyethylen konnen auch ausgepragte Varusdeformitaten korrigiert werden. Der Erfolg der UKA hangt von einer sorgfaltigen Patientenauswahl, detaillierten praoperativen Planung und Operationstechnik ab. Eine Erweiterung der klassischen Indikationskriterien fur UKA halten die Autoren fur gerechtfertigt. Drei Typen der mechanischen Varus-Deformitat konnen unterschieden werden: Typ 1 (isolierte intraartikulare Deformitat), Typ 2 (ubermasige Deformitat durch extraartikulare Varusdeformitat bei medialer UKA), Typ 3 (reduzierte Deformitat durch extraartikulare Valgusdeformitat bei medialer UKA). Diese Deformitaten sollten bei der Operationstechnik berucksichtigt werden.

Purpose Three surgical approaches in total hip arthroplasty (THA) were compared concerning: 1) clinical and radiological results; 2) innervation of the tensor fasciae latae and gluteal muscles; 3) clinical outcome of the nerve lesions; 4) sensitivity of the EMG analysis. Methods A total of 70 patients aged 39-79 years were evaluated clinically and electromyographically before and 3-9 months after THA in 2 centres using the anterolateral approach in 22, transgluteal approach in 33 and posterior approach in 15 patients, respectively. Results 1) Hip flexion, external rotation and Trendelenburg lurch were reduced and the centre of the rotation was higher after the anterolateral approach. 2) The inferior branch of the superior gluteal nerve of the tensor fasciae latae muscle was mostly damaged in the anterolateral approach (73% of lesions), whereas innervations of gluteus medius (9% of lesions) and maximus muscles (no lesion) were preserved. The transgluteal approach most often caused a partially denervated gluteus medius (81.8%) and the tensor fasciae latae (48%) and the gluteus maximus muscle only in 29%, respectively. After the posterior approach, partial denervation in the gluteus medius and maximus muscles were noted in 53.3% and 71.4%, respectively, whereas in the tensor fasciae latae muscle in only 14%. 3) The power of the abductors was not significantly reduced in partially denervated muscles. 4) The EMG examination is not sensitive enough to determine the relevant power of hip abductors. Conclusions Despite some disadvantages associated with the anterolateral approach, the transgluteal and posterior approaches are often connected with a partial lesion of the gluteus medius and maximus muscles. In all approaches, clinical sequelae are not significant in primary THA.

To perform a prospective evaluation of gait before and 2 years after total knee arthroplasty (TKA) and examine the influence of comorbidity and other joint problems on gait characteristics and their improvement after TKA.One hundred and eleven patients scheduled for TKA took part (34 men, 65 ± 10 y; 77 women, age 68 ± 9 y). Gait velocity, cadence, and ground reaction force parameters were measured before and 2 years after surgery. Patients completed a questionnaire to rate their pain and other joint problems. Comorbidity was measured with the American Society of Anaesthesiologists (ASA) score.Two years after TKA there were significant improvements (each p0.05) in gait velocity and cadence and most of the ground reaction parameters, though forces during loading/unloading remained lower for the operated leg than for the contralateral leg. Higher comorbidity and other painful joints of the lower extremities/spine had a consistent, negative influence (p0.05) on the absolute values achieved for the gait parameters although their improvement compared with baseline was independent of these factors.Comorbidity and other joint problems negatively influenced gait performance. These confounders should be taken into account when setting realistic patient expectations and when interpreting the success of TKA in the individual patient. Improvement in gait is however still possible, within the bounds of concomitant comorbidity.

Quadriceps muscle strength, which is essential for the function and stability of the knee, has been found to be impaired even years after arthroscopic partial meniscectomy. However, the neuromuscular alterations that could account for such muscle weakness remain unclear.We investigated (1) the side-to-side asymmetries in quadriceps muscle strength 6 months after arthroscopic partial meniscectomy, (2) the physiologic mechanisms (neural versus muscular) underlying muscle weakness, and (3) the impact of quadriceps weakness on muscle control at submaximal force levels.We tested 14 volunteers (10 men, four women) with an average age of 44 +/- 9 years (range, 24-59 years) at 6 +/- 1 months after unilateral medial arthroscopic partial meniscectomy. We measured maximal voluntary strength and muscle activation during isometric, concentric, and eccentric contractions using isokinetic dynamometry and surface EMG, respectively. We assessed vastus lateralis muscle size and architecture using ultrasonography. We measured muscle control at submaximal force levels with a repositioning test (knee proprioception) and a low-force target-tracking task (steadiness, accuracy).Isometric and concentric quadriceps strength and vastus lateralis EMG activity were lower on the involved than on the uninvolved side. Muscle architecture and muscle control did not differ between the involved and uninvolved sides.Our results showed quadriceps weakness exists 6 months after arthroscopic partial meniscectomy. As suggested by the EMG results, this is likely attributable to neural impairments (activation failure) that affect muscle control at maximal but not submaximal force outputs.Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: Hip abductors are the most important muscles around the hip joint. It is therefore essential to assess their function in a valid and reliable way. Since the optimal body posture for the assessment of hip abductor strength is unknown, we tested the validity and reliability of unilateral hip abductor strength assessment in three different body positions. We hypothesized that the validity would be better in the side-lying position because of the consistent stabilization of the contralateral (untested) hip. Methods: Sixteen healthy subjects participated in two identical testing sessions. Unilateral isometric hip abductor muscle strength was measured, with use of a stabilized commercial dynamometer, with the subject in the side-lying, supine, and standing positions. Construct validity was based on concomitant recordings of gluteus medius electromyographic activity from the tested and contralateral hips. The body position permitting greater muscle activation and abductor strength on the tested hip, while minimizing muscle activation in the contralateral hip (that is, lower contralateral-to-tested electromyographic ratio), was considered the most valid. Coefficients of variation, the Bland and Altman limits of agreement, and intraclass correlation coefficients were calculated to determine test-retest reliability of hip abductor strength. Results: Maximal hip abductor strength was significantly higher in the side-lying position compared with the standing and supine positions (p < 0.05). The contralateral-to-tested electromyographic ratio for the side-lying position was significantly lower than that for the supine and the standing position (p < 0.01). Test-retest reliability of strength measurements in terms of coefficients of variation (3.7% for side-lying, 6.1% for supine, and 4.2% for standing) and limits of agreement (±6.9% for side-lying, ±8.4% for supine, and ±7.5% for standing) was better in the side-lying position. All intraclass correlation coefficients were high to moderate (0.90 for side-lying, 0.83 for supine, and 0.88 for standing). Conclusions: The side-lying body position offers the most valid and reliable assessment of unilateral hip abductor strength. Clinical Relevance: We recommend the use of the side-lying body position whenever hip abductor function is assessed.

The clinical and radiographic results of 174 female and 86 male Innex (Zimmer, Warsaw, Indiana) mobile bearing total knee arthroplasty systems (245 patients) were evaluated, with particular emphasis on gender-related differences at five-year follow-up. Pre-operative Knee Society (KS) function and total scores were lower in women than in men. All KS scores showed a significant improvement at follow-up, but women still obtained lower KS function scores than men. Self-reported function was significantly better for male knees. No gender differences were observed for component alignment, while the occurrence of radiolucent lines, endosteal cavitations, and wear was significantly greater in male knees. Male Innex mobile bearing knees exhibited better clinical function and satisfaction than their female peers at five-year follow-up, despite inferior radiographic findings and higher revision rates.

Summary The aim of this investigation was to evaluate the inter- and intra-session reliability of spatio-temporal gait variables collected during walking and stair climbing with the Intelligent Device for Energy Expenditure and physical Activity (IDEEA) accelerometer-based system. Eighteen healthy subjects (10 men, 8 women) completed a standardized indoor circuit comprised of walking and stair climbing. Intra-and inter-session reliability was investigated for several pertinent spatio-temporal gait variables using intraclass correlations [ICC (3,1)]. Intra-session reliability during walking showed a high reliability of the IDEEA with ICCs ranging between 0·84 (number of steps) and 0·97 (single limb support/double limb support). The ICCs for stair climbing were slightly lower than those during walking with values ranging between 0·74 (step duration) and 0·92 (number of steps). Inter-session reliability during walking showed a high reliability of the IDEEA between all trials, with values ranging between 0·87 (speed) to 0·98 (step duration). The ICCs of stair climbing were again lower than those during walking with values ranging from 0·64 (swing duration) to 0·79 (number of steps). The IDEEA accelerometer-based system provided a highly reliable measurement of spatio-temporal variables, in healthy subjects, during walking with moderately reduced correlations during stair climbing.

Hip resurfacing is femoral bone preserving, but there is controversy regarding the amount of bone removed at the acetabular side. We therefore compared the implanted acetabular cup sizes in primary THAs between two resurfacing devices and a conventional press-fit cup using a series of 2134 THAs (Allofit cup 1643 hips, Durom Hip Resurfacing 249 hips, and Birmingham Hip Resurfacing 242 hips). The effects of patient demographics and cup position in the horizontal plane also were assessed. After controlling for gender, patients were matched for height, weight, body mass index, and age. The mean size for Allofit cups was smaller than the sizes for Durom and Birmingham Hip Resurfacing cups in women (49.9 mm, 51.6 mm, 52.3 mm, respectively) and men (55.1 mm, 56.7 mm, 57.8 mm; respectively). Although patient height was associated with the implanted cup size, the cup position in the horizontal plane had no effect on the size used. Larger cups were used with hip resurfacing than for THA with a conventional press-fit cup. However, additional studies are needed to determine whether these small differences have any clinical implications in the long term. The association of cup size and patient height should be considered in future studies comparing component sizes among different implants.Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Verlangsamtes Fortschreiten einer medialen Gonarthrose durch Verlagerung der Belastungsachse vom medialen in das laterale femorotibiale Kompartiment und Reduktion der vermehrten Druckbelastung auf der erkrankten medialen Seite. Isolierte mediale Gonarthrose im Fruhstadium. Symptomatische Varusfehlstellung. Entlastende Korrektur der mechanischen Beinachse bei knorpelrekonstruktiven Eingriffen wie der autogenen Chondrozytentransplantation. Korrektur posttraumatischer Varusfehlstellungen. Begleitende patellofemorale Arthrose, laterale Gonarthrose oder andere schmerzhafte Zustande des Kniegelenks. Eingeschrankter Bewegungsumfang. Knieinstabilitaten, da eine Progredienz zur Pangonarthrose wahrscheinlich ist. Schlechter Schraubenhalt bei ausgepragter Osteoporose. Schlechte periphere Durchblutung mit fehlenden Fuspulsen. Zustand nach lateraler Meniskektomie. Lateraler Zugang. Subkapitale Osteotomie der Fibula. Darstellen des lateralen Tibiakopfs. Partielle Osteotomie des proximalen Drittels der Tuberositas tibiae. Markieren der Gelenklinie. Einschlagen einer Halbrohrplatte uber einen Fuhrungsdraht parallel zur Gelenklinie, 1,5 cm distal davon. Aufsteigende Osteotomie des Tibiakopfs von kaudal-lateral nach kranial-medial. Die Osteotomie wird 2,5 cm distal der Platte angesetzt und sollte medial unmittelbar unter dem Fuhrungsdraht enden. Dabei soll die mediale Kortikalis intakt bleiben. Entnahme eines lateral basierten Knochenkeils gemas Planung. Schliesen der Osteotomie unter dosiertem Valgusstress. Uber eine durch das vorstehende Plattenloch gefuhrte 4,5-mm-Kortikalis-Zugschraube wird die Osteotomie unter Kompression gebracht. Wahrend der Hospitalisation regelmasige Behandlung auf der passiven Bewegungsschiene ohne Bewegungseinschrankung nach Masgabe der Beschwerden und Beginn mit isometrischen Kraftubungen. Mobilisation unter Teilbelastung mit 15 kg an zwei Unterarmgehstocken wahrend 6 Wochen postoperativ sowie ambulante Physiotherapie mit aktiven und passiven Bewegungsubungen. Danach radiologische Stellungs- und Konsolidierungskontrolle und je nach Befund schrittweiser Ubergang zur Vollbelastung bis zur 10. postoperativen Woche. Thromboembolieprophylaxe mit niedermolekularem Heparin bis zum Erreichen der Vollbelastung. Die eigenen, nach der hier beschriebenen Technik operierten Patienten wurden retrospektiv analysiert. Anhand von Kaplan-Meier-Uberlebenskurven konnte gezeigt werden, dass ein direkter Zusammenhang zwischen dem postoperativen Aktivitatsgrad der Patienten und der Langzeituberlebensrate nach 10–15 Jahren besteht. Auserdem hat das Ausmas der Achsenkorrektur einen direkten Einfluss auf das Langzeitresultat.

SummaryThe rate of bleeding complications after major orthopedic surgery approximates 2%. It is unclear whether a systematic switch of routine thromboprophylaxis has an impact on the rate of postoperative bleeding complications. We analyzed prospectively recorded postoperative bleeding complications and symptomatic venous thromboembolic events in 8,176 consecutive orthopedic patients at the Schulthess Clinic Zurich during a systematic switch of thromboprophylaxis from nadroparin to enoxaparin in the year 2004. Overall, 3,893 patients received nadroparin in the first nine-month observation period before the switch and 4,283 patients received enoxaparin in the second nine-month observation period after the switch. Overall, 96 (2.5%) patients in the first period and 70 (1.6%) patients in the second period suffered a postoperative bleeding complication requiring surgical revision, puncture, or transfusion (p

BackgroundThere is a lack of detailed information concerning patients’ sports and recreational activities after unicompartmental knee arthroplasty.HypothesisPatients treated by unicompartmental knee arthroplasty will be able to return to sports and activity.Study DesignCase series; Level of evidence, 4.MethodsThe authors surveyed 83 patients by postal questionnaires to determine their sporting and recreational activities at a mean follow-up of 18 ± 4.6 months (range, 12-28) after unicompartmental knee arthroplasty. For data analysis, patients were divided into groups of women and men, and older and younger patients (those above and below the median age of the group). The authors also assessed the state of general health (SF-36) of the patients at the time of the survey and compared the results with those of a matched (for age and side-diagnoses) reference population.ResultsBefore surgery, 77 of 83 patients were engaged in an average of 5.0 sports and recreational disciplines; postoperatively, 73 (88%) participated in an average of 3.1 different sports disciplines, resulting in a return to activity rate of 95%. The frequency of activities (sessions per week) was 2.9 preoperatively and remained constant at the time of survey (2.8). The group of older patients (mean age 73.0 y) revealed a significantly higher frequency than the group of younger patients (mean age 57.8 y). The minimum session length decreased from 66 minutes before surgery to 55 minutes after surgery. The most common activities after surgery were hiking, cycling, and swimming. Several high-impact activities, as well as the winter disciplines of downhill- and cross-country skiing had a significant decrease in participating patients. The majority of the patients (90.3%) stated that surgery had maintained or improved their ability to participate in sports or recreational activities. The patients generally scored very high on the SF-36 compared with the matched reference population. Higher SF-36 values in the physical-related domains correlated with an increased level of activity (r = 0.425). The preoperative body mass index showed a weak, negative correlation with the postoperative extent of activities (r = —0.282).ConclusionThe majority of patients returned to sports and recreational activity after unicompartmental knee arthroplasty. However, the numbers of different disciplines patients were engaged in decreased as well as the extent of activities. The activities in which most patients participated were primarily low- or midimpact. The patients scored higher on the SF-36 than age-related norms, which might be due to the patient-selection process for unicompartmental knee arthroplasty and geographical differences.

The present study aimed to compare quadriceps femoris muscle strength and fatigue between obese (grade II and III) and nonobese adults. Ten obese (mean age: 25 years; mean BMI: 41 kg/m(2)) and ten lean (mean age: 27 years; mean BMI: 23 kg/m(2)) men were tested. Quadriceps muscle fatigue was quantified as the (percent) torque loss during a voluntary isokinetic (50 maximal contractions at 180 degrees /s) and an electrostimulated (40 Hz) isometric protocol (5 min, 10% of the maximal torque). Maximal voluntary isometric and isokinetic torque and power were also measured. Voluntary torque loss was significantly higher (P0.05) in obese (-63.5%) than in lean subjects (-50.6%). Stimulated torque decreased significantly (P0.05) but equally in the two subject groups. Obese subjects displayed higher absolute (+20%; P0.01) but lower relative (i.e., normalized to body mass) (-32%; P0.001) muscle torque and power than their lean counterparts. Obese individuals demonstrated lower fatigue resistance during voluntary but not during stimulated knee extensions compared to their nonobese counterparts. Peripheral mechanisms of muscle fatigue -- at least those associated to the present stimulated test -- were not influenced by obesity. The observed quadriceps muscle function impairments (voluntary fatigue and relative strength) probably contribute to the reduced functional capacity of obese subjects during daily living activities.

Background No information is available concerning patients’ sports activity after hip resurfacing arthroplasty. Hypothesis Patients treated by hip resurfacing arthroplasty will be able to achieve a high level of sports activity. Study Design Case series; Level of evidence, 4. Methods We surveyed 112 patients by postal questionnaire to determine their sporting activities at a mean of 23.5 (range, 9—40) months after hip resurfacing surgery. Data were also analyzed separately for older and younger patients and women and men, respectively. Results Of 112 patients, 110 participated in an average of 4.6 sport disciplines after surgery, compared with 105 patients preoperatively engaged in an average of 4.8 disciplines. About 26% performed sports 4 times per week or more—almost 60% for longer than 60 min at each session. A high proportion of our patients were still engaged in downhill skiing (51%) and in high-impact disciplines such as tennis (12%) or contact sports (22%). More than 50% of the patients commenced sports within the first 3 months after surgery. During activities, 70% were completely pain-free. The group of older patients (mean age, 60.2 years) participated in more different disciplines with a higher weekly frequency and longer session length than younger patients (mean age, 46.4 years). Conclusion The present study reports for the first time on the detailed sports activity and activity extent after hip resurfacing arthroplasty. Our patients could return to a high level of sports participation after surgery. Age-related differences were found that have not yet been published. Nevertheless, further follow-up is necessary to assess the influence of high-level activity on loosening and revision rates after hip resurfacing 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.

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.

To analyze ligamentous stability and isokinetic strength of knee extensor and flexor muscles after anterior cruciate ligament reconstruction using 2 different autografts with identical fixation.This study implements a comparative case series design.Schulthess Clinic, Switzerland.A total of 153 consecutive patients (n = 87 bone-patellar tendon-bone [BPTB]/66 quadruple semitendinosus/gracilis tendons [QSGT] patients) who underwent BPTB and QSGT surgery were functionally assessed.All patients were functionally assessed (knee extension/flexion isokinetic strength and knee joint laxity) at a mean follow-up time of 11 months.Laxity was measured utilizing the Kneelax arthrometer, whereas isokinetic strength of the knee extensor/flexor muscle groups was measured using the Biodex Multi Joint System 2 (180 degrees/s and 300 degrees/s).The QSGT group had significantly greater knee joint laxity when compared with the BPTB group (P0.001). Furthermore, females in the QSGT group demonstrated the greatest knee joint laxity overall (P0.001). Additionally, a significant flexor torque deficiency was demonstrated in the QSGT group (P0.001); however, no differences in extensor torque were observed.The use of a BPTB autograft achieved better knee joint stability as well as greater knee flexor torque than the QSGT autograft. Both grafts exhibited a similar knee extensor torque deficit, indicating that only quadriceps strength is not graft-dependent.

The objective of this study was to determine gray-scale and power Doppler sonographic findings in patients with arthrofibrosis associated with total knee arthroplasty. SUBJECTS AND METHODS. From a consecutive cohort of more than 3000 mobilebearing total knee arthroplasties, 44 cases (1.5%) with arthrofibrosis were identified, of which 38 were recruited for a clinical and sonographic investigation. A control group of 38 patients with a well-functioning total knee arthroplasty was matched. Synovial hypertrophy, presence of neovascularity, patellar tendon thickness, and extent of effusion were assessed.Synovial membrane thickness was significantly (p0.001) increased in the arthrofibrosis group (medial, 3.4 mm; lateral, 3.0 mm; suprapatellar, 3.1 mm) when compared with the control group (medial, 2.0 mm; lateral, 2.0 mm; suprapatellar, 1.9 mm). When a cutoff of 3.0 mm was used, sonography had a sensitivity of 84% and a specificity of 82% for detecting arthrofibrosis. Neovascularity (rated as grades 0-3) of the synovial membrane and Hoffa's fat pad was significantly (por= 0.003) more pronounced in the arthrofibrosis group (medial, 1.1; lateral, 1.2; suprapatellar, 1.0; Hoffa's fat pad, 1.1) than in the control group (medial, 0.1; lateral, 0.3; suprapatellar, 0.2; Hoffa's fat pad, 0.1). No significant difference was seen between study groups with regard to the amount of joint effusion at three locations and with regard to patellar tendon thickness.Synovial membrane thickening and neovascularity are characteristic sonographic findings for the diagnosis of arthrofibrosis associated with total knee arthroplasty.

Objective: There is no consensus whether hip resurfacing arthroplasty (HRA) performs better than a stem-type total hip arthroplasty (THA). Therefore, the aim of this prospective comparative matched-cohort study was to answer the following questions: 1) Do gait parameters differ between HRA and THA patients at 3, 6, and 12 months after surgery? 2) Are there differences in lower extremity muscle strength at the same time points? 3) Does the selfreported outcome using validated instruments improve similarly in both groups? Methods: One experienced senior surgeon implanted either Durom HRA or CLS Spotorno THA in 34 male patients matched for anthropometric characteristics, preoperative scores and comorbidities. Preoperatively and at 3, 6, and 12 months, gait parameters, hip and knee muscle strength, clinical data and standardized outcome scores were assessed and compared between the two groups. Results: No significant group differences were found for all gait and strength variables. Passive range of motion and mean scores for the SF-36, Harris Hip Score and UCLA activity scale improved significantly over time without differences between groups. At 12 months, more HRA than THA patients were reporting groin pain on impingement testing (20% versus 0%; P

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.

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.

We present a prospective, two-centre radiostereometric analysis (RSA) regarding the stability of a flattened pole titanium press-fit cup (EP-FIT PLUS), and whether additional hydroxyapatite coating leads to faster bone ingrowth into the porous coating. Forty-two postmenopausal female patients (44 hips) undergoing total hip arthroplasty for primary osteoarthritis, selected to avoid hormonal factors influencing bone metabolism, were randomised to receive this cup with a titanium-plasma-sprayed surface with or without an additional hydroxyapatite coating. RSA was used to measure cup translation and rotation along three cardinal axes with respect to the host bone at the following time points: immediately postoperatively, at 6 weeks, and at 3, 6, 12, and 24 months. The most pronounced translation was proximal (0.11 mm) and posterior tilt (-0.27°). No difference in translation and rotation could be detected between the two groups. With the exception of one cup with an isolated radiolucent line

Item-Glatthorn JF, Casartelli NC, Petrich-Munzinger J, Munzinger UK, Maffiuletti NA. Validity of the Intelligent Device for Energy Expenditure and Activity accelerometry system for quantitative gait analysis in patients with hip osteoarthritis. Objective To evaluate the concurrent validity of an accelerometry-based system (Intelligent Device for Energy Expenditure and Activity) with a criterion instrument (Gaitrite) for the evaluation of spatiotemporal gait variables in orthopedic patients. Design Validity study. Setting Research laboratory in an orthopedic hospital. Participants Men with unilateral hip osteoarthritis (N=26; mean age ± SD, 54±9y). Interventions Not applicable. Main Outcome Measures Patients were asked to walk at normal and fast velocities while gait cycle, swing, double support, step length, cadence, and speed were concomitantly recorded with the 2 instruments. Concurrent criterion-related validity was examined using intraclass correlation coefficients and Bland-Altman limits of agreement. Results Intraclass correlation coefficients were acceptable for all gait parameters (range, .815–.997), except step length (.783). Limits of agreement were low for gait cycle, swing, and cadence, though relatively high for double support, step length, and speed. A significant bias between the 2 measuring instruments was consistently observed. Conclusions In patients with hip osteoarthritis, quantitative gait analysis with the IDEEA accelerometry system was satisfactory for the main temporal gait parameters, while double support, step length, and walking speed quantifications were invalid. The IDEEA system should be used with caution, and modifications of the system are recommended for improved use in clinical practice and research.

The seven Gruen zones are widely accepted for the assessment of periprosthestic bone mineral density (BMD) following traditional total hip arthroplasty, but no comparable rating system exists for hip resurfacing arthroplasty (HRA). We describe a seven-zone rating system around the femoral component of a typical HRA implant with a short metaphyseal stem and its intra- and inter-observer reliability. A cohort of 23 selected male patients underwent bone mineral density (BMD) measurements by dual-energy X-ray absorptiometry (DEXA) two years after HRA. After development of the new seven-zone rating system, reliability was assessed using intraclass correlation coefficients (ICC). The coefficient of variation was also determined. The new rating-system proved high reliability with ICCs for the intra-and inter-observer reliability ranging from 0.92 to 1.0. The coefficient of variation ranged from 1.4% to 3.3%. Mean BMD values were highest in the medial zones 5 to 7 and lowest in the lateral zones 1 to 3 and below the stem tip, corresponding to zone 4. We observed that BMD after HRA can be measured reliably in seven zones around the femoral component. The use of this easily applicable method in future investigations might enhance the comparability of study results. However, the rating system described may have limitations in HRA implants with very short metaphyseal femoral stems.

There is growing evidence that different resurfacing implants are associated with variable survival and revision rates. A registry analysis indicated the Durom resurfacing implant had high revision rates at 5 years, whereas three original studies reported low revision rates at short-term followups. Thus, the revision rates appear controversial. We therefore assessed (1) the survivorship including differences between women and men at a mean of 5 years after resurfacing with the Durom implant, and (2) clinical scores and radiographic parameters. We prospectively followed all 100 Durom hip resurfacings implanted in 91 patients (25 women and 66 men; mean age, 52 years) between 2003 and 2004. Survivorship analysis was performed with pending revision or revision for any reason as the endpoint. The minimum followup was 47 months (mean, 60 months; range, 47–72 months). At a mean of 5 years, 11 hips were revised for various reasons. Cumulative survival was 88.2% for all patients and 81.5% for women. The mean Oxford (OHS) and Harris hip (HHS) scores were 14.6 and 94.7, respectively. The mean UCLA activity level was 7.9. Sclerotic changes around the short femoral stem (pedestal sign) were detected in 40% of the hips. We observed considerable femoral neck thinning with component-to-neck ratios of 0.85 preoperatively and 0.82 at 5 years. Our study highlights a high revision rate 5 years after hip resurfacing with the Durom implant. This observation underlines previous findings from registry data and suggests that revision rates increase with time. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The objective of this preliminary study was to examine possible differences in gait characteristics between subjects operated by way of a direct anterior approach and a posterior approach for primary total-hip arthroplasty, and age-matched healthy controls. Fifty-one subjects walked over an instrumented mat at two different speeds (self-selected comfortable and faster than normal) and spatiotemporal gait parameters were calculated using a validated methodology. Despite excellent clinical and radiographic scores, and irrespective of surgical approach, patients demonstrated an impaired walking performance (lower velocity and shorter step lengths) during fast walking, but not at the self-selected comfortable speed compared with healthy controls. Subjects operated with the posterior approach reported significantly higher stiffness than anterior subjects, but similar pain and function. Six months after total arthroplasty for primary osteoarthritis of the hip, gait characteristics were comparable between subjects having received the direct anterior approach and the posterior approach.

Introduction Patient's expectations are variably reported to influence self-rated outcome and satisfaction after medical treatment; this prospective study examined which of the following was the most important unique determinant of global outcome/satisfaction after total knee arthroplasty (TKA): baseline expectations; fulfilment of expectations; or current symptoms and function. Methods One hundred and twelve patients with osteoarthritis of the knee (age, 67 ± 9 years) completed a questionnaire about their expectations regarding months until full recovery, pain, and limitations in everyday activities after TKA surgery. Two years postoperatively, they were asked what the reality was for each of these domains, and rated the global outcome and satisfaction with surgery. Multivariable regression analyses using forward conditional selection of variables (and controlling for age, gender, other joint problems) identified the most significant determinants of outcome. Results Patients significantly underestimated the time for full recovery (expected 4.7 ± 2.8 months, recalled actual time, 6.1 ± 3.7 months; P = 0.005). They were also overly optimistic about the likelihood of being pain-free (85% expected it, 43% were; P < 0.05) and of not being limited in usual activities (52% expected it, 20% were; P < 0.05). Global outcomes were 46.2% excellent, 41.3% good, 10.6% fair and 1.9% poor. In multivariable regression, expectations did not make a significant unique contribution to explaining the variance in outcome/satisfaction; together with other joint problems, knee pain and function at 2 years postoperation predicted global outcome, and knee pain at 2 years predicted satisfaction. Conclusions In this group, preoperative expectations of TKA surgery were overly optimistic. The routine analysis of patient-orientated outcomes in practice should assist the surgeon to convey more realistic expectations to the patient during the preoperative consultation. In multivariable regression, expectations did not predict global outcome/satisfaction; the most important determinants were other joint problems and the patient's pain and functional status 2 years postoperatively.

Quadriceps muscle strength is an important predictor of functional abilities in patients having TKA. However, because several daily activities are characterized by a limited time to generate force, it has been suggested that rate of force development (RFD) could better predict functional difficulties than maximal strength. We therefore hypothesized the side-to-side asymmetry would be larger for RFD than for maximal strength, and RFD asymmetry relates to subjective symptoms and/or functional daily living activities. We studied 31 subjects (17 women, 14 men) 6 +/- 1 months after undergoing TKA for unilateral osteoarthritis. Symptoms and limitations during activities of daily living were quantified using the knee outcome survey-activities of daily living scale (KOS-ADLS). Quadriceps maximal strength and RFD at different times (50 to 200 ms from contraction onset) were quantified during unilateral maximal voluntary isometric actions. Side-to-side asymmetries (involved versus uninvolved side) were larger for RFD (approximately 36%) than for maximal strength (approximately 24%). Subjective knee function related to all RFD asymmetry variables, but not to maximal strength asymmetry. In addition to maximal strength, quadriceps RFD in the first 100 to 200 ms from contraction onset provides an alternative functional outcome measure for individuals undergoing TKA.

We report on a 54-year-old rheumatoid arthritic female patient with uncontained type-III tibial and femoral bone defects at the time of revision total knee arthroplasty (TKA). The knee was reconstructed using a structural distal femoral allograft and a stemmed, semi-constrained knee prosthesis. We achieved the re-alignment of a severe preoperative valgus deformity of 40 degrees. Due to postoperative wound complications we had to perform a gastrocnemius muscle flap. At two-year follow-up the patient was free of pain and the Knee Society Score improved from 18 to 156 (p0.01). Radiographs revealed no loosening of the prosthetic components and progressive incorporation of the graft. Reconstruction of extensive uncontained bone defects in revision of TKA in rheumatoid arthritis can be managed by structural allografts; however, wound complications in those patients might necessitate soft tissue techniques.

Deceleration of the progression of medial gonarthritis via transfer of the mechanical load axis from the medial to the lateral femorotibial compartment and by reduction of compressive stresses in the medial compartment.Isolated early-stage unicompartmental medial gonarthritis. Symptomatic varus deformity. Adjustment of the mechanical load axis in reconstructive surgery such as autologous chondrocyte transplantation. Correction of posttraumatic varus deformities.Concomitant patellofemoral arthritis, lateral femorotibial arthritis, or other painful conditions of the knee. Limited range of motion. Knee instabilities, since a rapid development of a tricompartmental gonarthritis is likely to occur. Advanced osteoporosis. Poor peripheral circulation with an absent foot pulse. Lateral meniscectomy.Lateral approach. Subcapital osteotomy of the fibula. Preparation of the lateral tibial head. Partial osteotomy of the proximal one third of the tibial tuberosity. Marking of the joint line. A semitubular plate is placed over a guide wire parallel to the joint line, 1.5 cm distal to it, and is gently hammered into the tibial head with just the last hole seen outside. The lateral end of the plate is bent downward. Ascending osteotomy of the tibial head in an inferolateral to craniomedial direction. The osteotomy starts 2.5 cm distal to the plate and ends directly below the guide wire. The medial cortex remains intact. Excision of a lateral-based bone wedge according to the preoperative planning. The osteotomy is gently closed under valgus stress. A 4.5-mm cortical screw is aimed through the lateral hole of the plate into the distal fragment of the tibia and tightened until the osteotomy is brought under compression.During hospitalization, there is a periodic treatment with continuous passive motion without any limitation of range of motion and isometric training is taken up. Mobilization is permitted with partial load of 15 kg with two crutches during 6 weeks postoperatively. Ambulatory physical training with active and passive motion exercises. After 6 weeks, the load can be increased stepwise depending on the consolidation as seen on the control radiographs. Full weight bearing is generally reached after 10 weeks. During this time, thromboembolism prophylaxis with low-molecular-weight heparin is necessary.A retrospective analysis of the own patients treated with the described surgical technique was performed. On the basis of Kaplan-Meier survival analysis, it could be demonstrated that there is a correlation between the patients' level of activity and the long-term survival rate 10-15 years after the osteotomy. Moreover, the extent of correction has a direct influence on the long-term result.

Patients with osteoarthritis secondary to developmental dysplasia of the hip (DDH) typically are young and active, which might affect functional ratings or failure rates after resurfacing arthroplasty. We therefore evaluated 24 patients (32 hips; mean age, 44.2 years) after hip resurfacing performed for osteoarthritis secondary to DDH. We used the Harris hip score (HHS), the University of California, Los Angeles (UCLA) activity scale, and a sports and activity questionnaire. A radiographic analysis also was performed. We followed patients a minimum of 28 months (mean, 43 months; range 28–60 months). The HHS improved from a mean of 54.7 to 97.3 and UCLA activity levels increased from a mean of 5.3 to 8.6. All patients returned to sports activity at a mean of 11 weeks after surface replacement. There were no major differences in preoperative and postoperative participation in the most common sports and activities. Two of the 32 replacements (6%) failed. We detected femoral radiolucencies in 10 of the remaining 30 hips. Despite satisfactory outcomes in clinical scores, return to sports, and hip biomechanics, the failure rate of 6% was disappointing. Additional followup is important to assess if failure rates increase in these young, active patients. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

There is paucity of information available concerning the role of patellar height in unicompartmental knee arthroplasty (UKA). The present study was conducted to determine the patellar height before and after UKA and to assess possible effects on the early clinical outcome. We measured the patellar height before and after UKA in 83 consecutive knees using the Blackburne–Peel (BP) index and Insall–Salvati (IS) ratio and investigated the impact of the patellar height on the clinical outcome 2 years after surgery. BP values significantly decreased from 0.81 before surgery to 0.76 postoperatively (P

The aim of this study was to evaluate the reliability of isokinetic and isometric assessments of the knee extensor and the flexor muscle function using the Con-Trex isokinetic dynamometer. Thirty healthy subjects (15 males, 15 females) were tested and retested 7 days later for maximal strength (isokinetic peak torque, work, power and angle of peak torque as well as isometric maximal voluntary contraction torque and rate of torque development) and fatigue (per cent loss and linear slope of torque and work across a series of 20 contractions). For both the knee extensor and the flexor muscle groups, all strength data - except angle of peak torque - demonstrated moderate-to-high reliability, with intraclass correlation coefficients (ICC) higher than 0.86. The highest reliability was observed for concentric peak torque of the knee extensor muscles (ICC = 0.99). Test-retest reliability of fatigue variables was moderate for the knee extensor (ICC range 0.84-0.89) and insufficient-to-moderate for the knee flexor muscles (ICC range 0.78-0.81). The more reliable index of muscle fatigue was the linear slope of the decline in work output. These findings establish the reliability of isokinetic and isometric measurements using the Con-Trex machine.

This study aimed to determine whether a lower-limb trajectory-tracking task performed on a leg press machine, that is commonly adopted in both rehabilitation and resistance training settings, could yield reliable assessment of motor coordination in able-bodied individuals. Twenty-two female subjects allocated to two experimental groups were tested and retested after 48-72 h. Group A was fully familiarized with the experimental procedures before each test while group B received only verbal instructions. The unilateral coordination test consisted of target tracking during a simulated half squat including eccentric and concentric actions. In both groups, tracking error showed significant test-retest reliability with ICC values of 0.77-0.80 (p < 0.05). Significant group (A < B) and time (day 2 < day 1) main effects were found for tracking error, while there was no significant influence of action mode and dominance. Tracking error significantly decreased in the group A ( approximately 15%) but not in the group B on retest. Action mode (eccentric versus concentric), side dominance and familiarization on day 1 had no effect on tracking error. However, movement control significantly improved at day 2, thus confirming the occurrence of short-term motor learning and the sensitivity of the present trajectory-tracking test. For the first time, a simple test for the assessment of motor coordination during multi-joint closed-kinetic chain action of lower limb muscles has been proposed. Its uniqueness is represented by the specificity for rehabilitation and resistance training settings. Further studies with larger sample groups (e.g., male subjects and patients) and including neurophysiological measurements are needed.

Knee Surgery, Sports Traumatology, Arthroscopy, 13 (3), ISSN:0942-2056, ISSN:1433-7347

The failure rate of repaired short external rotator muscles was determined in 20 total hip replacements done in 19 patients. The piriformis, both obturator and gemellus muscles, and the capsule were released close to the femur in a single flap leaving the tendon-capsule junction intact. After implantation of the prosthetic components, the flap was transosseously reattached with three grasping stitches, each encompassing the entire tendon-capsule junction. Radiopaque markers were attached to each side of the suture. The distance between markers was measured intraoperatively and then determined on radiographs 1 day and 3 months postoperatively; 25 mm or more and at least double the distance measured intraoperatively indicated failure. In 15 of the 20 hips the repair failed; in three hips the repaired flap was pulled out within the first day, and in 12, within 3 months. Capsular enhanced repairs of the short extensor rotator muscles, using the technique described, largely are unable to withstand forces that occur at the site of repair during the healing process. The quality of other repair techniques should be determined to identify superior techniques.

The knee is the major joint most commonly affected by osteoarthritis. Before the advent of knee replacement, conservative measures such as debridement, osteotomy and arthrodesis represented the basics of surgical management. Therefore, end-stage knee arthritis often led to a significant proportion of disabled patients. This was radically changed with the development of knee arthroplasty, which paralleled that of total hip arthroplasty in the 1970s.

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 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. Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 7 (September), 2001: pp 732–736

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.

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.

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.

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.

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.