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.

Autologous chondrocyte implantation for traumatic full-thickness cartilage defects of the knee in 14 patients: 6-year functional outcomes.

BACKGROUND: Autologous chondrocyte implantation (ACI) was introduced in 1987 in Sweden by Brittberg and Peterson for the treatment of severe chondral defects of the knee. Here, our objective was to evaluate mid-term outcomes of ACI in young athletic patients with deep chondral defects of the knee after trauma. HYPOTHESIS: ACI is effective in filling full-thickness chondral defects of the knee. PATIENTS AND METHODS: We prospectively monitored 14 patients, with International Cartilage Repair Society grade III or IV lesions, who underwent ACI between 2001 and 2006. Standard evaluation measurements were used. Mean age at surgery was 37.7 years (range, 30-45). A history of surgery on the same knee was noted in ten (67%) patients. The defect was on the medial femoral condyle in 11 patients, lateral femoral condyle in two patients, and both femoral condyles in one patient. Mean defect surface area after debridement was 2.1cm(2) (1-6.3). RESULTS: After a mean follow-up of six years, improvements were noted in 12 (86%) patients, with an International Knee Documentation Committee (IKDC) score increase from 40 (27.6-65.5) to 60.2 (35.6-89.6) (P=0.003) and a Brittberg-Perterson score decrease from 54.4 (11.8-98.2) to 32.9 (0-83.9) (P=0.02), between the preoperative assessment and last follow-up. The visual analogic scale pain score decreased from 66.3 (44-89) to 23.2 (0-77) (P=0.0006). In two (14%) patients, no improvements were detectable at last follow-up. The remaining 12 patients were satisfied and able to resume sporting activities, albeit at a less strenuous level. Two ACI-specific complications occurred, namely, periosteal hypertrophy treated with debridement in one patient and transplant delamination in another. DISCUSSION: Our findings are consistent with previous reports but cover a longer follow-up period. Although the outcomes are promising, longer follow-ups are needed to confirm the long-term effectiveness of ACI. LEVEL OF EVIDENCE: IV, prospective therapeutic study.

Reproducibility of an optical measurement system for the clinical evaluation of active knee rotation in weight-bearing, healthy subjects.

INTRODUCTION: A knee is typically evaluated passively by a clinician during an office visit, without using dedicated measurement tools. When the knee is evaluated with the patient standing and actively participating in the movement, the results will differ than when the knee is passively moved through its range-of-motion by the surgeon. If a precise measurement system was available, it could provide additional information to the clinician during this evaluation. HYPOTHESIS: The goal of this study was to verify the reproducibility of a fast, flexible optical measurement system to measure rotational knee laxity during weight-bearing. MATERIAL AND METHODS: Two passive reflective targets were placed on the legs of 11 subjects to monitor femur and tibia displacements in three dimensions. Subjects performed internal and external rotation movements with the knee extended or flexed 30°. During each movement, seven variables were measured: internal rotation, external rotation and overall laxity in extension and 30° flexion, along with neutral rotation value in 30° flexion. Measurement accuracy was also assessed and the right and left knees were compared. Reproducibility was assessed over two measurements sessions. RESULTS: The calculated intra-class correlation coefficient (ICC) for reproducibility was above 0.9 for five of the seven variables measured. The calculated ICC for the right/left comparison was above 0.75 for five of the seven variables measured. DISCUSSION: These results confirmed that the proposed system provides reproducible measurements. Our right/left comparison results were consistent with the published literature. This system is fast, reproducible and flexible, which makes it suitable for assessing various weight-bearing movements during clinical evaluations. LEVEL OF EVIDENCE: Level III, experimental study.

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.

Is transverse acetabular ligament an anatomical landmark to reliably orient the cup in primary total hip arthroplasty?

INTRODUCTION: Accurate positioning of the acetabular cup in primary total hip arthroplasty is critical to decrease the rate of dislocation. Inaccurate orientation of the cup is the most common error during this procedure. Target acetabular orientation is still controversial. An original study found a dislocation rate of 0.6% when the cup was aligned with the transverse acetabular ligament (TAL). HYPOTHESIS: TAL is a patient-specific anatomical landmark and a tool for cup orientation. MATERIALS AND METHODS: Eight cadaveric pelves (14 hips included for study) were harvested in toto at our research laboratory. Anatomical versions of the TAL, labrum and horns were measured in relation to the anterior pelvic plane. A navigator sensor and an optoelectronic device (Motion Analysis™) were used. RESULTS: Anatomical versions of the TAL, horns and labrum averaged 1.9° (range, -8° to +13.3°), 3° (range, -12.2° to 14°), and 26.3° (range, 17.4° to 41.8°), respectively. DISCUSSION: To our knowledge, this is the first study to report the orientation of the periacetabular soft-tissues. TAL anteversion was outside the safe zone described by Lewinnek, while labrum anteversion was within this safe-zone. We discuss the reference used, Lewinnek's safe zone, and functional orientation of the implants. Lewinnek's safe-zone does not seem to be valid. The TAL seems to be a specific reference for each patient but its reliability must still be confirmed as an adequate reference for positioning the cup in total hip arthroplasty.

Patella osteochondritis dissecans end stage: The osteochondral mosaicplasty option.

INTRODUCTION: Patellar damage during osteochondritis dissecans of the knee is rare. There were two objectives to this study: evaluate the functional results of surgical treatment by mosaicplasty in this disease as well as evaluate articular surface reconstruction and cylindrical bone plugs incorporation. MATERIALS AND METHODS: Six consecutive cases of patella osteochondritis dissecans in young athletes were treated using mosaicplasty by the same senior surgeon between 2002 and 2007. All these cases presented ICRS stage IV osteochondritis dissecans with an empty defect lesion. The average age at diagnosis was 20.5 ± 9.2 years old. The pre- and post-operative clinical evaluation was based on the IKDC subjective knee evaluation, the Lysholm and Tegner scores, CT arthrography and MRI. RESULTS: Evaluation of the functional results of surgical treatment at a mean follow-up of 26 months showed an average IKDC subjective evaluation score of 66.3, a Lysholm score of 85 and a Tegner score of 5.7 (37.2, 58.3 and 3.5 respectively before surgery). The radiological evaluation showed articular surface reconstruction with satisfying congruency and good incorporation of the graft into the bone at the receptor site, except in one patient in whom a 5mm diameter cartilage defect and a loose body were identified. DISCUSSION: Osteochondral grafting with the mosaicplasty technique has been shown to be effective and give satisfying functional results. The problem of the per-operative cylindrical bone plugs choice requires to be addressed during the procedure course itself, according to the patella lesion location.

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.

Mobile-bearing insert translational and rotational kinematics in a PCL-retaining total knee arthroplasty.

INTRODUCTION: Total knee prostheses with a mobile-bearing insert were developed to provide nonconstrained joint range of motion while reducing friction forces. The purpose of this study was, based on weightbearing X-rays, to evaluate the mobility of the polyethylene tibial insert in relation to the femoral and tibial components. We studied the results of a cementless total knee arthroplasty (TKA) retaining the posterior cruciate ligament (PCL), with a mobile-bearing platform in rotation and anteroposterior translation (Innex Anterior-Posterior Glide, Zimmer) with a mean 23-month follow-up duration after surgery. HYPOTHESIS: Both anterior-posterior tibiofemoral translation and intraprosthetic axial rotation occur between the mobile polyethylene insert and the tibial endplate. MATERIAL AND METHOD: In a series of 51 primary TKA, the three-dimensional (3D) kinematics of the femoral, tibial, and mobile insert components were determined using a computerized matching system between the prosthetic 3D models and the radiographic images of the implants on three lateral follow-up weightbearing knee X-rays: films were taken in full extension, at 45 degrees flexion, and at maximum flexion. RESULTS: There was a statistically significant increase in the internal rotation of the mobile tray with flexion, (up to a mean -3+/-3 degrees between the femoral box and the mobile tray [p<0.0001] and up to a mean -5+/-7 degrees between the tibial tray and the mobile tray [p<0.0001]). The mobile tray did not translate in relation to the tibial endplate from extension to 45 degrees flexion (0+/-2 mm [range: -5 to 6 mm]). However, from 45 degrees to maximum flexion, a statistically significant mean 1+/-2 mm (range: -2 to 9 mm) of anterior translation (p<0.0001) was found. DISCUSSION: The extent of insert mobility varies from one study to another. Some have reported relatively limited mobility stemming from a superior surface that is not highly congruent, (thus allowing anterior-posterior and mediolateral translation through gliding of the femur in contact with the insert). Other studies have reported mobile-bearing tray mobility in relation to the tibial endplate and minimal rotation at the femoral component level. In this series of PCL retaining TKA with a mobile-bearing platform, the mobile-bearing platform showed a progressive increase in internal rotation during flexion. Most of this rotational mobility occurred between the mobile platform and the tibial endplate, confirming our hypothesis. However, with flexion, the femoral component increased its mobility relatively to the platform. During flexion, an anterior-posterior translation occurred between the femoral implant and the tibial insert, and between the tibial insert and the tibial endplate, but the direction of the mobile tibial insert translation remained unpredictable with this nonconstrained implant design used. LEVEL OF EVIDENCE: Level IV. Prospective non-controlled therapeutic study.

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.

Kinematics of a cementless mobile bearing posterior cruciate ligament-retaining total knee arthroplasty.

Mobile bearing (MB) total knee arthroplasty (TKA) was developed to provide low contact stress and unconstrained joint motion. We studied a consecutive series of 41 knees with mobile-bearing, posterior cruciate-retaining (CR) TKAs to determine if kinematics resembled normal knees or if kinematics changed over time. Patients were studied at 3 and 21 months average follow-up with weight-bearing radiographs at full extension, 30 degrees flexion and maximum flexion. Shape-matching techniques were used to measure TKA kinematics. Implant hyperextension, maximum flexion and total ROM increased with follow-up. Tibial rotation and condylar translations did not change with time. The medial condyle did not translate from extension to 30 degrees, but translated 5 mm anteriorly from 30 degrees to maximum flexion. Lateral condylar translation was 3 mm posterior from extension to 30 degrees, with no translation from 30 degrees to maximum flexion. Tibiofemoral kinematics in CR-MB-TKAs were stable over time, but did not replicate motions observed in healthy knees. The mobile tibial insert showed rotation and translation at both follow-up examinations, but the patterns of translation were not predictable.

[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.

[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.

Inter-observer agreement in the identification of the two bundles of the anterior cruciate ligament using magnetic resonance imaging.

BACKGROUND: Magnetic resonance imaging has become the method of choice to diagnose meniscal and ligament lesions of the knee. New approaches to the surgical treatment of partial anterior cruciate ligament tears led us to try to distinguish the two bundles of that ligament with MRI and to evaluate inter-observer agreement in different viewing planes. METHODS: Images of 50 right and 50 left ligament-intact knees were examined in the coronal and axial viewing planes. Each sequence was independently read by a radiologist and a medical student to note, in each viewing plane, the number of images in which the two-bundle structure of the ligament was clearly seen. Cohen's Kappa coefficients were used to determine inter-observer agreements. RESULTS: The percentage of sequences in which the two bundles were distinguished by the radiologist and the student on one image at least were 82 versus 73% in the coronal plane and 90 versus 93% in the axial plane, respectively. The average number of successive images with clear bundles was higher in the axial (2.7 vs. 1.7) than in the coronal plane (2.2 vs. 1). There was a poor inter-observer agreement in the coronal plane (k=0.176) but an intermediate agreement in the axial plane (k=0.385 or 0.522 depending on number pooling). CONCLUSIONS: The axial viewing plane seems more favourable to distinguish the two bundles of the anterior cruciate ligament with the best possible reproducibility. An oblique-axial plane is deemed to insure a clearer diagnosis of partial tears.

[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.

Magnetic resonance imaging as a tool to predict reparability of longitudinal full-thickness meniscus lesions.

Prediction of meniscus reparability is useful for surgeons to optimise surgical scheduling and to inform patients about postoperative management. This study was designed to determine the accuracy of MRI in predicting the reparability of longitudinal full-thickness meniscus lesions. We studied 100 MRIs of longitudinal full-thickness medial or lateral meniscus lesions located from the meniscosynovial junction to the axial part of the meniscus. The MRI criteria of reparability were a peripheral rim smaller than 4 mm and a lesion longer than 10 mm. At arthroscopy the menisci were considered as reparable when the lesion was located in red-red or red-white zones and when it was more than 1 cm in length. A heterogeneous or homogeneous aspect of the meniscus body was also considered. The length of the meniscus lesion averaged 17.6 mm and the thickness of the rim 3.4 mm. A heterogeneous signal of the axial fragment and of the rim was found in 11 cases and in 48 cases, respectively. In 90 cases, there was no difference between the MRI-predicted reparability and the arthroscopic findings. Global sensitivity of MRI to determine reparability of full-thickness meniscus lesions was 94%, increasing to 96% for the medial meniscus and dropping to 83% for the lateral meniscus. Global specificity was 81%, and was higher for the lateral meniscus (90%) than for the medial one (82%). Global positive predictive value was 0.94 and global negative predictive value was 0.82. A heterogeneous aspect of the rim did not compromise arthroscopic reparability whereas a heterogeneous aspect of the axial fragment indicated an irreparable meniscus. The described MRI criteria can predict meniscus reparability. Their accuracy is limited for lateral meniscus lesions close to the popliteal hiatus and for very young active patients in whom repair of white-white lesions can be attempted. Longitudinal full-thickness meniscus lesions are a good indication for repair in young active patients.

Comparative study of knee anterior cruciate ligament reconstruction with or without fluoroscopic assistance: a prospective study of 73 cases.

INTRODUCTION: Correct placement of both tibial and femoral tunnels is one of the main factors for a favorable clinical outcome after anterior cruciate ligament (ACL) reconstruction. We used an original system of computer assisted surgery (CAS). The system, based on fluoroscopic guidance combined with special graphical software of image analyzing, showed to the surgeon, before drilling, the recommended placement of tibial and femoral tunnel centers. We compared the first anatomical and clinical results of this procedure to the usual one single incision technique. MATERIALS AND METHODS: We conducted a prospective study on 73 patients; 37 patients were operated on with CAS and 36 without CAS, by the same senior surgeon. The mean age was 27 years for both groups. Every patient was reviewed at an average of 2.2 years (range 1-4.5) by an independent observer, using IKDC scoring system, KT-1000, and passive stress radiographs. RESULTS: Time between ACL rupture and reconstruction averaged 30 months for both groups. CAS needed 9.3 min extra surgery time. Clinical evaluation was graded from A to C as per the IKDC scoring system: 67.6% A, 29.7% B, 2.7% C with CAS; and 60% A, 37.1% B, 2.9% C without CAS. IKDC subjective knee evaluation score averaged 89.7 with CAS and 89.5 without CAS. Pre operative KT-1000 maxi manual differential laxity averaged 7. At revision time, all the patients after CAS had a differential laxity less than 2 and 97.7% without CAS. Stress X-rays differential laxity averaged 2.4 mm with CAS and 3 mm without CAS. The area of dispersion of the tunnels' center was smaller on the femoral side using the CAS method. There was no statistically significant difference between both groups using IKDC score, KT-1000 and passive stress radiographs. CONCLUSIONS: The CAS method provided a more accurate and reproducible tunnels placement without clinical significant effect.

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.