Lactate accumulation in response to supramaximal exercise in rowers.

The aim of this study was to test (a) three methods to estimate the quantity of lactate accumulated (QLaA ) in response to supramaximal exercise and (b) correlations between QLaA and the nonoxidative energy supply assessed by the accumulated oxygen deficit (AOD). Nine rowers performed a 3-min all-out test on a rowing ergometer to estimate AOD and lactate accumulation in response to exercise. Peak blood lactate concentration [(La)peak ] during recovery was assessed, allowing QLaA(m1) to be estimated by the method of Margaria et al. Application of a bicompartmental model of lactate distribution space to the blood lactate recovery curves allowed estimation of (a) the net amount of lactate released during recovery from the active muscles (NALR max ), and (b) QLaA according to two methods (QLaA(m2) and QLaA(m3)). (La)peak did not correlate with AOD. QLaA(m1), QLaA(m2) and QLaA(m3) correlated with AOD (r = 0.70, r = 0.85 and r = 0.92, respectively). These results confirm that (La)peak does not provide reliable information on nonoxidative energy supply during supramaximal exercise. The correlations between AOD and QLaA(m2) and QLaA(m3) support the concept of studying blood lactate recovery curves to estimate lactate accumulation and thus the contribution of nonoxidative pathway to energy supply during supramaximal exercise.

Knee rotational laxity and proprioceptive function 2 years after partial ACL reconstruction.

PURPOSE: The aim of our study was to evaluate knee rotational laxity and proprioceptive function 2 years after partial anterior cruciate ligament (ACL) reconstruction. According to our hypothesis, partial ACL reconstruction could restore knee laxity and function to the intact level. METHODS: We conducted a study in fifteen consecutive patients undergoing partial ACL reconstruction. Fifteen anteromedial bundle tears were identified intraoperatively. Partial ACL reconstructions were performed by the same senior surgeon using a single-incision technique. A bone-patellar tendon-bone graft was used in 13 cases and a double-stranded semitendinosus graft in 2 cases of chronic patellar tendonitis. The mean age at surgery was 29 years. The time between ACL tear and surgery averaged 7.8 months (range 2.5-29.5 months). We developed an original device designed to assess knee proprioception (passive and active) and measure weight-bearing rotational laxity in full extension and at 30°, 60° and 90° of knee flexion. All measurements were taken on both the reconstructed and healthy knee. RESULTS: The mean follow-up of the study was 3.4 years (range 2.6-4.4). No statistically significant difference in rotational laxity, active or passive proprioception could be observed between the reconstructed and healthy knee. External rotation was significantly greater than internal rotation in full extension and at 30° of flexion in the reconstructed and the healthy knee (P < 0.05). For each knee, active proprioception was found to be significantly different (higher) than passive proprioception (P < 0.05). CONCLUSION: Our study did not detect any difference in rotational laxity and proprioception between the reconstructed and the healthy knee. Therefore, partial ACL reconstruction appears to restore satisfactory knee laxity and function in case of partial ACL tear. LEVEL OF EVIDENCE: IV.

The role of the medial ligamentous structures on patellar tracking during knee flexion.

PURPOSE: The influence of the medial patellar ligamentous structures on patellar tracking has rarely been studied. Thus the main purpose of this cadaveric biomechanical study was to determine the influence of the medial patellofemoral (MPFL), medial patellomeniscal (MPML) and medial patellotibial (MPTL) ligaments on the three-dimensional patellar tracking during knee flexion. This study was conducted using a validated cadaveric optoelectronic protocol for analysis of patellar kinematics. METHODS: For each cadaveric knee study, four successive acquisitions were performed; first was studied patellar tracking in healthy knees, then the junction between MPFL and vastus medialis obliquus (VMO) was sectioned, the MPFL was released at its patellar attachment and finally was released the insertion of the MPML and MPTL. RESULTS: In this study, the MPFL accounts for 50-60% of the medial stabilization forces of the lateral patellar shift during patellar engagement in the femoral trochlea. This work confirm and clarify the role of the MPFL as the primary stabilizer of the patella during the initial 30° of knee flexion. Moreover, this study shows no significant results regarding the stabilizing action of the VMO on the patella during knee flexion. CONCLUSION: This in vitro study, conducted with an experimental protocol previously validated in the literature, helps quantify the actions of the MPFL, the VMO, and the MPML/MPTL respectively, and identify areas of joint motion where these structures have the most significant influence. This confirms the importance of reconstruction in the treatment of chronic patellar instability. During its reconstruction, care should be taken to adjust the MPFL balance during the initial 20°-30° of flexion.

Throwing performance is associated with muscular power.

The aim of the present study was to test the hypothesis that performance in throwing events is associated with muscular characteristics of both upper and lower limbs. Thirty-eight male throwers volunteered to participate. Bench press and half squat tests were conducted on a guided barbell. The barbell displacement signal was recorded using a kinematic system. Maximal power, corresponding optimal velocity and force (P(max)S, V(opt)S, F(opt)S and P(max)BP, V(opt)BP, F(opt)BP for half squat and bench press, respectively) were extrapolated from the power-velocity relationship. Lower limb stiffness (K) was determined during maximal hopping. The results demonstrated that P(max)S and P(max)BP were correlated with each thrower's season's best performance (SBP, R=0.54, P<0.01 and R=0.71, P<0.001, respectively). P(max)S expressed relative to body mass was not correlated with SBP. K was significantly correlated with SBP (R=0.66, P<0.001). The relationship between P (max)BP expressed relative to body mass and SBP remained significant ( R=0.54, P<0.001). The results of the study suggest that high strength and stiffness values for lower limbs and strength and velocity characteristics for upper limbs may be associated with athletic throwing performance.

Medial patellofemoral ligament anatomy: implications for its surgical reconstruction.

The purpose of the present study, based on 23 cadaveric knees, was to perform a detailed anatomical analysis of the medial patellofemoral ligament (MPFL), especially its femoral attachment, its relationships with the vastus medialis obliquus (VMO) and the medial collateral ligament, with the objective of improving its surgical reconstruction. The femoral insertion of the MPFL was defined using an orthonormal frame centered on the middle of the femoral MPFL insertion. The whole measurements were taken using a millimetric compass with a precision of +/-1 mm. The MPFL was always observed, its length was 57.7 +/- 5.8 mm, the junction between the VMO and the MPFL always present measured 25.7 +/- 6.0 mm. When it comes to MPFL reconstruction, the key point is its positioning in the femoral insertion because it is this insertion that is going to restore isometry. By using the orthonormal frame it has to be positioned 10 mm behind the medial epicondyle and 10 mm distal to the adductor tubercle.

[Patellar fracture after anterior cruciate ligament reconstruction using a bone patellar tendon bone transplant: a comparative study of two harvesting techniques]. / Fracture de la patella après prélèvement os-tendon patellaire-os pour ligamentoplastie de reconstruction du ligament croisé antérieur : incidence du type de prélèvement.

PURPOSE OF THE STUDY: We studied the incidence and the impact of patellar fracture after anterior cruciate ligament (ACL) reconstruction, comparing two harvesting techniques. MATERIAL AND METHODS: Series A included Kenneth Jones ligamentoplasties (n=1234). The distal and central part of the patella were harvested using an oscillating saw and a gouge. Series B included 676 Mac InJones reconstructions performed during the same period. The patellar cut was done from porximal to distal its attachment were harvested with a manual wire saw. The bony harvesting site was filled with cancellous bone. RESULTS: There were three postoperative transversal patellar fractures (0.24%), all in series A. Functional outcome was disappointing but there was no impact on knee stability. DISCUSSION: The fact that the Mac InJones technique does not involve a transversal cut would apparently prevent secondary fracture.

[Results of self-centering patellofemoral prosthesis: a retrospective study of 57 implants]. / Résultats de la prothèse fémoropatellaire autocentrique: à propos d'une série continue de 57 prothèses.

PURPOSE OF THE STUDY: The aim of this retrospective analysis was to report results obtained with a self-centering patellofemoral prosthesis. We wanted to determine whether self-centering still has indications for the treatment of patellofemoral osteoarthritis. MATERIAL AND METHODS: This was a continuous series of 57 knees operated on since 1986 in the same center for implantation of a self-centering patellofemoral prosthesis (Medinov then Depuy). Eight patients died and four were lost to follow-up. Two knees were excluded from the analysis after revision with a PFP. We report here the outcome of 43 prostheses at mean follow-up of six years two months (range 78 months to 15 years). The IKS score (200 points) and the ADL scale (in %) were recorded. The position of the prosthesis was assessed on plain X-rays. Mean age at implantation was 67.2 years. The main reasons for surgery were osteoarthritis secondary to dysplasia (60%) and primary disease (31.1%). RESULTS: At last follow-up, the IKS score was 157.2 points (range 76-195). The mean ADL score was 74.1/100 (48.8-96.3). The IKS evaluation showed good outcome in 66.7% of knees. The ADL scale gave a less satisfactory outcome: 57.7% good outcome for this scale which takes into account all knee functions for activities of daily life. Outcome was better among patients with trochlear dysplasia. Eleven patients (24.4%) had had revision surgery for total knee arthroplasty. Preoperatively, the trochlear angle was smaller in revision cases (p=0.023). In these patients, the first prosthesis was more anterior (p=0.004) with a greater horizontal axis (p=0.015). DISCUSSION: Our outcomes were less satisfactory than the average results in the literature. It must be noted however, that the concept of a good outcome depends on the scale used for assessment. We found in our series a 10% difference between the ADL scale and the IKS score. Independently of the assessment scale used, outcome was better in knees with osteoarthritis secondary to dysplasia. An analysis of the X-ray findings disclosed technical errors leading to failure. The outcome of patellofemoral prosthesis depends essentially on two factors: technical precision and patient selection. CONCLUSION: In light of these findings, we have come to limit still further the rare indications for patellofemoral prostheses. The typical indication is isolated advanced patellofemoral osteoarthritis secondary to patellofemoral dysplasia unresponsive to medical treatment in patients aged 50-70 years. Revision with a total knee arthroplasty required changing the patellar insert if worn. We have not had any particular problem with revision total knee arthroplasty after patellofemoral prosthesis.

[Ochronosis or black cartilage disease]. / L'ochronose ou la maladie du cartilage noir.

We report two cases of ochronosis. This rare disease (1/1,000,000) transmitted by recessive autosomic inheritance results from an enzyme disorder. Clinically, the disease begins by black deposits in connective tissue followed by a group of symptoms, particularly involving the joints, and then destructive joint disease affecting the larger joints. Diagnosis is often established late. Early detection is important, preoperatively if possible, in order to avoid the serious complication of infectious endocarditis. These patients require adapted multidisciplinary care associating social support and symptomatic treatment. Drug therapy is currently under study and appears to provide effective symptom relief.

Effects of radiograph projection parameter uncertainty on TKA kinematics from model-image registration.

Model-image registration techniques have been used extensively for the measurement of joint kinematics in vivo. These techniques typically utilize an explicit measurement of X-ray projection parameters (principal distance, principal point), which is easily done for prospective studies. However, there is vast opportunity to derive useful information from previously collected clinical radiographic films where the projection parameters are unknown. The purpose of this study was to determine variation in measured knee arthroplasty kinematics when the X-ray projection parameters were unknown, but bounded. Based on the clinical radiographic protocol, a nominal principal point was chosen and eight additional points +/-2 and +/-5 cm in the horizontal and vertical directions were defined. Tibiofemoral kinematics were determined for all nine projection parameter sets for a series of 10 lateral radiographs. In addition, the principal distance was varied +/-15 cm and tibiofemoral kinematics were determined for these two projection sets. Measured joint kinematics varied less than 0.6 degrees and 0.4 mm for +/-2 cm variations in principal point location, and 0.7 degrees and 0.6 mm for +/-5 cm variations in principal point location. Measured joint kinematics varied less than 0.6 degrees and 0.7 mm for +/-15 cm variations in principal distance. Variation in X-ray principal point and principal distance over clinically bounded ranges has a small effect on knee arthroplasty kinematics computed from model-image registration with high-quality clinical radiographs.

[Anterior cruciate ligament revision: analysis and results from a series of 74 cases]. / Les reprises de ligamentoplastie du ligament croisé antérieur: analyse et résultats d'une série de 74 cas.

PURPOSE OF THE STUDY: This was a retrospective series of patients who underwent revision ligamentoplasty of the anterior cruciate ligament (ACL). We wanted to assess the functional outcome after this type of surgery and search for potential prognostic factors. MATERIAL AND METHODS: The series included 74 patients, mean age 34 years (range 21-59 years). The initial ligamentoplasty was performed with a synthetic ligament (n=16), an autograft (n=57) or an allograft (n=1). Differential laxity (KT-1000 maximal manual) was 7 +/- 2.5 mm. Anterior drawer was measured on the stress x-rays in 20 degrees flexion: medial 8 +/- 4.7 mm, lateral 8.3 +/- 4.9 mm. Mean time to revision surgery was 78 months. Reconstruction was performed arthroscopically in 69 knees. The implant used for the revision reconstruction was an autograft: patellar tendon (n=42), quadriceps tendon (n=15), hamstring tendon (n=13), patellar tendon and quadriceps tendon (MacInJones) (n=3), fascia lata (n=1). A meniscal tear was noted in 24 knees and a cartilage lesion in 35. RESULTS: Outcome was assessed at mean 21.2 months follow-up. The mean IKDC function score was 71.7 (range 21.8-100). 78% of patients considered their knee normal or nearly normal and 88% presented a positive Lachmann. Mean differential laxity measured with KT-1000 (maximal manual) was 2 +/- 1.7 mm. Stress x-rays revealed a mean differential laxity measured at 3.7 +/- 2.3 mm medially and 6.3 +/- 4.3 mm laterally. The presence of a meniscal lesion favored osteoarthritic degradation. Presence of chondral lesions altered the functional outcome significantly and limited resumption of sports activities. An initial repair using a synthetic ligament affected the functional outcome after revision surgery and favored or aggravated chondral lesions. DISCUSSION: The clinical results we have obtained with revision ACL ligamentoplasty are comparable to previous series reported in the literature. The functional outcome is not as good as after first-intention repair, especially if the initial plasty was done with a synthetic ligament and the knee presented meniscal or cartilage damage.

[Axial lower limb alignment and knee geometry in patients with osteoarthritis of the knee]. / Analyse segmentaire de la déformation frontale dans les gonarthroses fémoro-tibiales latéralisées.

PURPOSE OF THE STUDY: We conducted a retrospective radiographic study to identify and quantify medial and lateral misalignments in candidates for total knee arthroplasty. MATERIAL AND METHODS: We studied a discontinuous series of 101 patients (164 knees) among candidates for total knee arthroplasty seen between 1990 and 2002. We selected a random sample for study. Exclusion criteria were any history of fracture, surgical treatment, rheumatoid disease, or congenital disorder. A first group of 136 genu varum knees was identified in 82 patients (mean age 72 years, mean weight 79 kg). A second group of 28 genu valgum knees was identified in 19 patients (mean age 67 years, mean weight 71 kg). The standard radiograms were digitalized for semi-automatic measurements using the Metros software. We recorded overall deformation, femoral valgus, tibial varus, HKA angle, HKS angle (mechanical/anatomic axis of the femur) and angle C (horizontal inclination of the ankle to the ground). All measures were compared between each other for each patient to search for relations. RESULTS: In the genu varum group (136 knees), mean overall deformation was 9 degrees , mainly due to tibial misalignment (5.5 degrees ) with a 1 degrees femoral valgus component. The HKS angle was 6.3 degrees , and lateral joint gap 4.3 degrees ; the C angle was 4 degrees . Overall varus followed tibial varus (p<0.01). Ankle inclination followed tibial varus (p<0.01). In the genu valgum group (28 knees), overall deformation was 4.2 degrees , mainly due to femoral misalignment (5.6 degrees) with 1 degrees tibial varus and a medial joint gap of 2 degrees . The HKS angle was 4.7 degrees and the mean C angle -4 degrees . Overall valgus was related to femoral valgus (p<0.001). Tibial varus was greater with greater femoral valgus (p<0.01). In both groups, the HKS angle was smaller with greater femoral valgus. DISCUSSION: Semi-automatic measurements on digitalized films enabled excellent reproducibility. Causes of error were related to limb rotation at acquisition. This study showed that genu varum worsens because of tibial wear followed by ligament distension, while for genu valgum, worsening predominantly results from femoral wear. The ankle joint line was nearly horizontal in one-third of the limbs, even when there was a major misalignment of the lower limb. The HKS angle was quite variable in both morphotypes, but was smaller with greater femoral valgus in both groups. CONCLUSION: Measuring all components involved in medial and lateral knee misalignment is very useful for understanding the morphotype of each individual knee before performing osteotomy or implanting a knee prosthesis.

[One-stage reconstruction of the two cruciate ligaments with a single autogenous graft from the extensor system: techniques and results of 25 chronic cases]. / Reconstruction simultanée des 2 ligaments croisés par un transplant autogène unique: technique et résultats à propos de 25 laxités chroniques.

PURPOSE OF THE STUDY: Chronic tears of both cruciate ligaments are rarely encountered. Management practices have varied. One-stage reconstruction of both ligaments using arthroscopically implanted allografts was proposed starting in 1996 for such chronic laxity but only 44 cases have been reported in six papers mixed in with recent cases raising very different problems. Treatments using allografts or autogenous grafts or both implanted arthroscopically have often been combined with open surgery. We report a retrospective analysis of 25 knees treated with the same technique from 1983 to 2004: reconstruction with a single transplant taken from the extensor system. MATERIAL AND METHODS: A 30-cm lenght patella tendon-patella-quadriceps tendon graft was harvested. The patellar block was fixed in a hole drilled under the tibial spine, the patellar tendon replacing the posterior cruciate ligament and the quadriceps tendon passing through the lateral condyle and replacing the anterior cruciate ligament before implantation on Gerdy's tubercle, this also creating an extra-articular plasty with the same implant. Medial, lateral and posterior plasties were performed, depending on the radiographic assessment of laxity. Twenty-five knees with major laxity and instability were operated on, including 14 in two-stage operations. The differential anterior drawer was 10+/-3 mm medially and 9+/-5 mm laterally. The posterior drawer at 70 degrees was 15+/-4 mm medially and 10+/-6 degrees laterally. The total anteroposterior laxity of the medial compartment was 29 mm, it was 30 mm for the lateral compartment. Lateral laxity was considered major (>10 degrees ) in 17 knees and medial laxity in 7. Lateral and medial laxities were associated in eleven knees. Hyper-extension was very severe in five knees. RESULTS: Functional outcome at mean 6.5 years follow-up (range 1-21) was satisfactory (except in three knees) allowing renewed occupational activity. Resumption of sports activity was less marked and none of the knees was in IKDC class A, corroborating results in the literature. Anatomic outcome was assessed on the radiological drawer decrease which was modest, mean gain in the anterior drawer measuring 4 and 5 mm in the medial and lateral compartments and mean gain in the posterior drawer measuring 5 mm medially and 3 mm laterally. Peripheral laxity was corrected for best. DISCUSSION: Classically, one or other of the cruciate ligaments is repaired, sometimes both, but in a two-stage procedure associating two different methods and autogenous tendon grafts. One-stage reconstruction of both cruciate ligaments with a single autogenous graft and a wide approach has not led to any complications. One-stage reconstruction using this technique has several advantages: one anterior incision, single transplant which also enables lateral plasty, short immobilization time with rapid rehabilitation.

[Analysis of meniscal lesions accompanying anterior cruciate ligament tears: A retrospective analysis of 156 patients]. / Lésions méniscales constatées lors de la reconstruction du ligament croisé antérieur: siège et nature dans une série continue de 156 patients.

PURPOSE OF THE STUDY: The purpose of this retrospective study of a continuous series was to document preferential types and localizations of meniscal lesions accompanying anterior cruciate ligament tears and to demonstrate the relationships between meniscal lesions, patient age and time from trauma to surgery. MATERIAL AND METHODS: One hundred fifty-six patients with no history of meniscal lesions underwent ligamentoplasty in 2003. All procedures were performed by the same operator. The time from trauma to surgery was 31.6 months on average. This was a retrospective continuous series using data from detailed operative reports. RESULTS: An isolated lesion of the medial meniscus was observed in 25.6% of cases. There was an isolated lesion of the lateral meniscus in 21.8% and lesions of both menisci in 9%. The most frequent injury was a longitudinal fissuration, for both menisci. Patient age and time from trauma to surgery were statistically correlated with presence of a medial lesion. There was no statistical relationship for the lateral meniscus nor for type of meniscal injury. DISCUSSION: The proportion of lesions to the lateral meniscus appeared to be unaffected by age or time to surgery after trauma, suggesting that lateral meniscal lesions occurred at the time of the initial curciate injury. On the contrary, the incidence of medial lesions increased with time and patient age, confirming the important role of the medial meniscus to block anterior displacement of the knee. We thus recommend early repair of anterior cruciate ligament tears in order to avoid medial meniscectomy which would increase with increasing time from injury to surgery and thus affect the postoperative outcome.

[Intra-articular reconstruction of the anterior cruciate ligament with and without extra-articular supplementation by quadricipital tendon plasty: seven-year follow-up]. / Influence d'une ligamentoplastie extra-articulaire latérale sur les résultats de la reconstruction du ligament croisé antérieur avec le ligament patellaire avec 7 ans de recul.

PURPOSE OF THE STUDY: Reconstruction of the anterior cruciate ligament (ACL) is a common procedure, but use of lateral reinforcement is still a subject of debate. The purpose of this study was to compare two randomized series of ACL reconstructions, one using an intra-articular method (patellar tendon autograft) and the other an intra- and extra-articular method (Mac-InJones). MATERIAL AND METHODS: From January 1995 to March 1998, 63 knees underwent surgery for ACL reconstruction. Inclusion criteria was significant medial differential laxity measured between 7 and 12 mm on passive dynamic x-rays as 20 degrees flexion. Group 1 (patellar tendon intra-articular reconstruction) included 34 patients (27.1+/-7.5 years) and group 2 (intra-articular reconstruction plus extra-articular quadircipital tendon plasty) included 29 patients (28.5+/-12 years). The IKDC score was determined for 72% of the knees in group 1 and 68% in group 2 at seven years follow-up on average (102 and 93 months respectively). Anterior laxity was measured radiographically and with KT-1000. The position of the tunnels was controlled using the Aglietti method. RESULTS: The subjective functional score was 83.6+/-3.5 in group 1 and 83.5+/-3.5 in group 2. The overall IKDC knee score classes for group 1 were 0% A, 52.4% B, 28.6% C, and 19% D and for group 2 were 5.5% group A, 50% group B, 33.3% group C, and 11.1% group D. In group 1, the pivot test was negative in 61.9% and noted stage 1 in 28.6% and stage 2 in 9.5%. In group 2, the pivot test was negative in 78.9% and noted stage 1 in 15.8% and stage 2 in 5.3%. The KT-1000 showed no difference in gain in laxity: 31% for group 1 and 27% for group 2. Similarly, radiographically there was no difference with a 43.9% gain in differential laxity for the medial compartment and 45.3% for the lateral compartment in group 1. In group 2 the corresponding values were 51.9% and 41.8%. The position of the tunnels was the same in the two groups. DISCUSSION: In a preliminary study with two years follow-up, the results in these two series were not significantly different. It was concluded that there was not clear advantage to adding the extra-articular lateral plasty. At the present 7-year follow-up, pivoting appears to be better controlled in the lateral plasty group (p=0.23), but with no significant difference for laxity for both knee compartments. The inclusion criteria would be different today and would be based on the laxity of the lateral compartment.

[Accuracy of total knee replacement bone cuts using a conventional ancillary system: 300 Innex total knee arthroplasties]. / Précision des coupes osseuses dans l'arthroplastie totale du genou à l'aide d'un ancillaire conventionnel: trois cent poses consécutives de prothèses Innex.

PURPOSE OF THE STUDY: Short-term functional results and long-term outcome in terms of stability and wear greatly depend on the precision of the bone cuts. We wanted to know whether conventional ancillaries are still competitive in terms of accuracy in comparison with computer-assisted navigation systems. A few comparative studies favor navigation, but have generally only included a small number of patients. We studied radiographically a prospective consecutive series of 300 total knee prostheses (Innex, Zimmer) implanted with the conventional technique by the same operator. MATERIAL AND METHODS: A telegonometric view in the upright position and a short lateral view were obtained in all patients. In the AP view, implants were measured in comparison with the mechanical axis of the femur (F) and the tibia (T). On the lateral view, the prosthesis-tibial shaft angle (PT) was measured from the proximal portion of the tibial shaft and the prosthesis-femoral shaft angle (PF) from the distal portion of the femur. The same operator made all measurements using the same optimal conditions. The series included 178 women and 122 men, mean age 72 +/- 8 years who presented genu varum (n = 248 knees) and genu valgum (n = 52 knees): degenerative disease (n = 238), polyarthritis (n = 4), hemophilic arthropathy (n = 3), necrosis (n = 3), revision of unicompartmental prosthesis (n = 8), and osteotomy (n = 44). RESULTS: The standard x-ray protocol was performed at two months in all patients. The mechanical axis (HKA) was 179.4 +/- 2.4 degrees (range 173-186 degrees) and was +/- 3 degrees in 87% of knees with no difference for varum and valgum. F was 90.1 +/- 1.4 degrees (87-95), with +/- 3 degrees for 98.7%. T was 89.3 +/- 1.5 degrees (85-94) with +/- 3 degrees for 95.6%. PF was 88.6 +/- 1.6 degrees (84-93) for 87%, PT was 87 +/- 2 degrees (81-93) with +/- 3 degrees for 94%. The four cuts were within +/- 3 degrees for 227 prostheses (77%), within +/- 2 degrees for 156 (52%) and within +/- 1 degrees for 56 (18%). Measurements made again one year after implantation for 203 knees gave the same results. Operative time for implantation was 68 +/- 23 minutes for implantation and 85 +/- 23 minutes including complete closure (less than 60 minutes for 68 knees). DISCUSSION: The accuracy of each cut was satisfactory on average with a small standard deviation. Recent data in the literature show that the accuracy in our series is comparable with that obtained currently with navigation systems. In light of this experience, it can be seen that better precision can be achieved for each of the cuts. CONCLUSION: The accuracy of conventional instrumentation systems is still comparable with that obtained with computer-assisted surgery. The purpose of this study was not to question the benefit of navigation, but to establish a basis upon which progress can be measured. The results enabled a more realistic comparison of the precision of navigation systems and also can be comforting for operators still using conventional ancillaries.

[Osteochondritis dissecans of the femoral condyles: report of 892 cases]. / L'ostéochondrite disséquante des condyles fémoraux.

PURPOSE OF THE STUDY: Osteochondritis rarely involves the femoral condyles. Discovery in this localization raises several questions concerning the nature of the articular cartilage, the potential for spontaneous healing, and, in the event of a free fragment, the outcome after its loss or repair. MATERIAL AND METHODS: This multicentric study included 892 pediatric and adult cases, the cutoff between two series being defined by fusion of the inferior growth plate. We excluded medical or surgical osteochondritis, cases involving the patella, osteochondral fractures, juvenile polyosteochondrosis, adult osteonecrosis, and osteochondritis beginning after the age of 50 years. RESULTS: Mean age at diagnosis was 16.5 years. Mean age at treatment onset was 22 years. Pain was the predominant symptom. 80% of cases were unilateral and 70% involved the medial condyle. The anatomic lesions were different in adults, showing more advanced degradation. At diagnosis, Bedouelle stages Ia and IIb constituted 80% of the cases observed among children while in adults, 66% were Bedouelle stages IIb to IV. Outcome was very good for the majority of children with Hughston clinical stage 4 while half of the x-rays were Hughston stage 3 and 4. There were thus a large percentage of children with abnormal xrays whose disease history was not yet terminated. In the adult series, the percentages of Hughston 3 and 4 was about the same as clinically. The x-rays were rarely perfectly normal since half of the clinical stage 3 patients were noted in stage 4. An abnormal x-ray with a very good clinical presentation was observed in a very large proportion of patients. DISCUSSION: It is difficult to interpret the plain x-ray and identify patients with a potentially unfavorable prognosis. We defined three radiographic classes: defect, nodule and empty notch. The Bedouelle classification uses information from all available explorations, particularly MRI and arthroscopy. Numerous therapeutic methods are used. Interruption of sports activities is the first intention treatment for children. Data in the literature and the findings of this symposium do not demonstrate any beneficial effect of immobilization on healing compared with simple abstention from sports activities. Transchondral perforation is a simple operation with low morbidity. In 85% of cases, it was used for lesions with an intact joint cartilage considered stable in 96% of cases. Healing was achieved in six months for 48% if the growth plate had not fused. The fragment was fixed in 43% of the cases with a loose cartilage fragment. Outcome was fair but degraded with the state of the joint cartilage and thus the stability of the fragment. Fixation must stabilize the fragment but not prevent further consolidation via osteogenesis. This is why deep perforations are drilled beyond the ossified area and additional osteochondral grafts are used. The Wagner operation gives less satisfactory results than more complicated procedures. Removal of a sequestrum is a simple, minimally invasive procedure with an uneventful postoperative period, but in the long term it favors osteoarthritic degradation, especially when performed in adults. Mosaic grafts give good mid term results. Morbidity is low especially if the grafts are harvested above the notch. The question of chondrolysis around the grafts was beyond the scope of this study. Chondrocyte grafting is difficult to accomplish and is expensive. The mid term results are good for large lesions. Osteotomy is logical only in the event of early stage osteoarthritic degradation. DECISION ALGORITHM IN CHILDREN AND ADOLESCENTS: If the plain x-ray reveals a defect (class I), simple interruption of sports activities should be proposed. Two situations can then develop. First, in a certain number of patients, the pain disappears as the defective zone ossifies progressively. Complete cure is frequent before the age of 12 years. In the second situation, the knee remains painful and the x-ray does not change or worsens to a class II nodular formation. In this case an MRI must be obtained to determine whether the joint cartilage is normal. There are two possibilities. First, the osteochondral fragment is viable and most probably will become completely re-integrated, particularly if the lesion is far from the growth plate. Necrosis is the other possibility. Transchondral perforations are needed in this case. If on the contrary the cartilage is altered, there is little hope for spontaneous cure. Arthroscopy may be needed to complete the exploration. Fragments, especially if there is a large surface area, must be fixed. Perforations to favor revascularization are certainly useful here. In the last situation (class III), the fragment wobbles on a thin attachment or has already fallen into the joint space. This is the type of problem generally observed in adults. The decision algorithm in adults is the same as in children for the rare nodular aspects (class II). There could be a discussion between transcartilage perforation and fixation. If there are a large number of fragments, fixation may not be fully successful and the lesion might be considered class III. For class III lesions, three operations can be used: removal of the sequestrum, mosaic bone-cartilage grafts, or autologous chondrocyte grafts. At the same follow-up, mosaic grafts give better results than excision of sequestra. It may be useful to remove sequestra in a limited number of situations: if there is just a small area of osteochondritis, the lesion is old and partially healed, or the zone is non weight-bearing. For other lesions, we favor mosaic grafts. We still do not have enough follow-up to assess the long-term outcome with these mosaic grafts, but simple excision clearly favors osteoarthritic degradation. Can chondrocytes grafts be compared with mosaic grafts? Chondrocyte grafts have been used for very large lesions and have given results similar to mosaic grafts. It might also be possible to combine fixation of a loose fragment and a mosaic graft. LESSONS FROM THIS STUDY: 1) The prognosis of osteochondritis is better before than after fusion of the growth plate but the lesion does not always heal in children. 2) Presence of osteochondritis requires complementary anatomic and functional exploration to determine the stability and the vitality of the fragment. 3) Attention must be taken to perform transchondral perforations early enough, particularly in children. 4) Screw fixation is not always sufficient. The trophicity of the fragment and its blood supply must be improved. 5) Mosaic grafts are preferable to excision of the fragment. 6) Chondrocyte grafts will be more widely used in the future.

Aluminas with dispersoids. Tribologic properties and in vivo aging.

Three base alumina ceramics with dispersoids: monoclinic zirconia alumina (A5Z), tetragonal zirconia alumina (A20Z) and aluminalon (Aa20) have been investigated because of their improved mechanical properties with reference to pure alumina (AI203). Bending strength and fracture toughness are twice higher than alumina for the most toughened. These two parameters were measured by four-points bending tests after 1 week, 1, 2, 3, 6, 12 months of non loaded in vivo aging in wistar rats. They showed a little decrease for AI203 and Aa20 and a total stability for A5Z and A20Z even after one year. For tribologic study of the ceramic/polyethylene combination, cylinder against plane and pin on flat tests were conducted on an alternative movement with hip parameters of speed and load in presence of ringer solution. For the most representative test (pin on disk), the friction coefficients were nearly the same for all materials but UHMWPE wear volume was twice lower against A20Z than against AI203. A20Z/UHMWPE combination would be very interesting as new friction couple for total hip arthroplasty. Further studies are currently conducted.

Soccer accidents in the French Rhône-Alpes Soccer Association.

The analysis of 6153 accidents reported to the insurance company of the French Rhône-Alpes Soccer Association, for the 1980-81 season was undertaken, providing a survey of acute pathology in French soccer accidents and an estimation of the cost of this pathology to French society. Findings from this study include: injuries--ankle sprain is the most common; fractures prevail in the young players pathology; exposure--the average risk is one accident for 20 matches; the highest risk is for the senior category; collisions with opponents is the main cause of accidents; the first 5 minutes of the second half have a peak of accidents; the players exposure is roughly the same whatever their position on the ground; risk--winter should not increase the risk if the matches are played under good conditions; the risk is unevenly distributed according to the level of practice; cost--the cost for France over 1 year was estimated at US$20,000,000 and the total number of sick leave days at 2000 years; games with several accidents are very common in January and for the adult category. Consequently, tightening up the safety measures would be a very good investment.

Comparison of reconstruction of the anterior cruciate ligament with and without a Kennedy ligament-augmentation device. A randomized, prospective study.

In a randomized, prospective study, sixty-four patients who were operated on for a torn anterior cruciate ligament were divided into two groups: thirty patients (the control group) had repair with the Marshall-MacIntosh technique alone, and thirty-four patients had repair with the same technique but with the addition of a Kennedy ligament-augmentation device. The preoperative characteristics were essentially identical in the two groups. The postoperative management, resumption of athletic activities, and occurrence of complications were also similar. All patients were followed for more than two years. No significant functional or clinical difference between the two groups was found with respect to residual laxity determined either from dynamic radiographs or with the KT-1000 arthrometer. There was no evidence that the addition of the Kennedy ligament-augmentation device gave results that were superior to those obtained with the Marshall-MacIntosh technique alone.

Effects on intact femora of dogs of the application and removal of metal plates. A metabolic and structural study comparing stiffer and more flexible plates.

Studies of flexible plates made of plastic have shown that less osteoporosis develops beneath them than beneath rigid metal plates. However, to date plastic plates of appropriate physical properties and biocompatibility are not available for use in humans. To determine if a similar beneficial effect could be obtained using metal plates, the effects of thick chromium cobalt plates were contrasted in experiments in dogs with the effects of thinner plates of similar design made of titanium, 6-aluminum, 4-vandium. A significant reduction in the osteoporosis was obtained by use of the more flexible plates. Following plate application a delayed, massive, transient stimulus to bone formation occurred endosteally, periosteally, and intracortically. Despite this, a substantial decrease in bone mass occurred, primarily mediated by endosteal bone resorption. Intracortical porosity played little or no role in net bone loss. The major effects subsided by six months. Recovery after plate removal was predominantly the result of endosteal new-bone formation.