THE PRIMARY STABILITY OF A CEMENTLESS HIP PROSTHESIS UNDER THE COMPRESSIVE LOADING

The objective of this research is to better understand the problems of primary stability of cementless hip prosthesis. The present study is aimed to develop a finite element model of the coupled system "femur-cementless prosthesis" which represents the implant in its environment particularly under the compressive loading. Its primary stability is investigated by quantifying the migration of the femoral stem in the femur and by analyzing the stress and strains engendered. We have made experimentations on ten fresh human femurs. A good agreement is observed between the experiments and the prediction by our finite element model for the prosthetic head displacement

Early outcomes of THA using uncemented dual-mobility cups with additional fixation screws

Background: The use of fixation screws with uncemented cups is controversial particularly for dual mobility (DM) cups where perforation of the articular surface could compromise implant longevity. We aimed to compare outcomes of total hip arthroplasty (THA) using uncemented DM cups with supplementary screw fixation versus simple press-fit fixation. Methods: From 235 consecutive THAs performed using uncemented DM cups, 203 were fixed by simple press-fit and 32 fixed with additional screws. The Oxford hip score (OHS) and EuroQol 5 Dimensions (EQ-5D) score were available at 3.3±1.1 years. To enable direct comparison, each screw fixation cup was matched to three simple press-fit cups using propensity scores, based on age, sex and bone quality. Results: The two groups had equivalent age, body mass index, gender distribution, femoral morphology and bone quality. Compared to the press-fit group (n=96), the screw fixation group had more surgical antecedents (p=0.032), higher femoral neck angles (p=0.028), and received slightly larger cups (p=0.036). Revision was required for two (6%) screw fixation cups (only one implant-related) and one (1%) press-fit cup (none implant-related). There were no differences between OHS (19±8 vs 18±7, p=0.682) nor EQ-5D (0.63±0.37, p=0.257). Conclusions: Revision rates were greater for DM cups fixed with additional screws than for those fixed by simple press-fit, but clinical scores were equivalent. There was only one implant-related revision (acetabular fracture) in the screw fixation group and it is unclear whether this is related to the additional screws or to patient/surgical factors

The evolution of osteoarthritis in 103 patients with ACL reconstruction at 17 years follow-up

AIM: To evaluate the functional and radiological outcome of a bone-tendon-bone anterior cruciate ligament reconstruction, at long-term follow-up. METHODS: A retrospective study of 148 patients, of which 103 were available for long-term follow-up. Complete functional and radiological evaluation (International Knee Documentation Committee scale) were performed in 89 out of the 103 patients [Anderson AF. Rating scales. In: Fu FH, Harner CD, Vince KG, (Eds.). Knee Surgery, Baltimore, Williams and Wilkins vol. 1, 1994; 12, pp. 275-296]. RESULTS: The mean follow-up time was 17.4 years. Subjectively, 88% of the patients were very satisfied or satisfied. According to the IKDC score 55% had type A symptoms, 29% type B, 12% type C, and 4% type D. The IKDC ligament evaluation showed 14.9% type A, 44.8% type B, 35.8% type C, and 4.5% type D. At the review 22.7% had a narrowing 50% (D). Onset of osteoarthritis showed an association with the status of the medial meniscus. Knees with a preserved (healthy or sutured) medial meniscus had a significantly (p < 0.05) better radiological outcome. Among these, 9% had a joint space narrowing 50% (D). Medial meniscectomy, residual laxity, and femoral chondral defects were associated with osteoarthritis. CONCLUSION: The outcome of anterior cruciate ligament reconstruction plus extra-articular tenodesis is good in the very long term, particularly in knees with a preserved medial meniscus

Confrontation de la planification radiographique préopératoire et des données postopératoires lors de la mise en place des prothèses totales de hanche non cimentées

PURPOSE OF THE STUDY: For hip prosthesis surgery, the challenge is to obtain optimal function of the instrumented hip but also to eliminate any limb length discrepancy, correct the femur offset and guarantee the center of rotation of the hip joint. Preoperative planning for total hip arthroplasty (THA) enables determination of the appropriate length for the prosthetic neck and the size and eventually the type of implants to use. From a prospective series of 86 patients who underwent first-intention THA for implantation of a noncemented prosthesis, we studied the precision of the outcome as function of the preoperative planning. We also ascertained whether the preoperative planning was sufficient to provide the measurements necessary for correct implant position. MATERIAL AND METHODS: We analyzed a prospective series of patients who underwent first-intention THA from January 2004 through January 2006. To be eligible for inclusion, patients could not have a THA of the contralateral hip. The series was composed of 58 females and 28 males, mean age 70.2 years (range 45-93). The reasons for THA were primary degenerative disease (n=76) and aseptic osteonecrosis (n=10). The contalateral hip was intact and free of osteoarthritis with an anatomic presentation considered to be normal. The standard X-ray protocol included an anteroposterior view of the pelvis in the upright position and 10 degrees internal rotation obtained preoperatively and three months postoperatively. All radiographic measurements were made by the same investigator using a manual nondigitalized technique. We compared planning parameters (pivot size and type, length of the neck, and size of the cup) with the final outcome in order to determine the compliance with the preoperative planning. All operations were performed in the lateral supine position under general anesthesia and by the same surgeon. The posterolateral Moore approach was used. All implants were press fit without cement, both for the cup and for the femoral piece. RESULTS: All planning parameters selected for study (offset, size of the head and the cup, length of the neck) were available for 32 hips, giving an overall conformity of 37%. The length of the neck was as planned in 75% of hips, the size of the cup in 62% and the size of the femoral stem in 64%. The offset defined preoperatively was never changed during the operation. Ideal implantation (+/- 5mm for all criteria selected for study) was obtained in 60% of hips; the height of the center of rotation was reproduced in 81% and the lateralization in 84%. Femur lateralization was reproduced in 75% of the hips and hip offset in 66%. Leg length discrepancy was avoided in 85% of the patients. DISCUSSION AND CONCLUSION: Preoperative planning reliably predicts the final offset of the implanted femoral stem. It is more difficult to predict the size of a press fit cup but in our experience the difference does not greatly affect restitution of the hip anatomy. We readily changed the length of the neck during the operation if necessary and have found that the leg length has been better with this approach. This leads to the observation that all of the planning parameters are not fully accurate because of the magnification effect, anatomic conditions, or possible defective execution. While the overall rate of conformity was low, looking at the results for each element separately provided a useful element for each phase of the operation. We recommend planning a medium length neck so it can be easily changed during the operation. The availability of offset measurements is particularly important to control hip lateralization and leg length. Current advances in computer-assisted surgery should be helpful in improving the imperfections of preoperative planning

Two cases of deliberate implant mismatch in knee arthroplasty

Cases: Knee arthroplasty is increasingly common with good clinical results. However, there is a cohort of patients whose native knee anatomy may not marry well with standard implants. The current authors describe two cases (one unicompartmental knee arthroplasty (UKA), one total knee arthroplasty (TKA)), during which deliberately implanting an implant designed for the contra-lateral distal femur (TKA) or contralateral femoral condyle (UKA) respectively, led to a better fit than correct-sided implants. Conclusion: The authors share their experience to raise awareness of a potential solution to such an intra-operative challenge and suggest that implant customisation may ultimately address challenges with grossly abnormal native anatomy

Arthroscopy of the knee after unicompartmental arthroplasty

Le résultat fonctionnel des prothèses unicompartimentales est parfois imparfait. Les douleurs ne sont pas toujours expliquées par des signes cliniques patents, biologiques ou radiologiques présents, par exemple, en cas d’usure, de fracture, de descellement ou de défaut de positionnement des implants. Ce travail nous porte à discuter la place de l’arthroscopie dans le traitement et le diagnostic de certaines complications des prothèses unicompartimentales. Parmi une série de 214 prothèses unicompartimentales réalisées entre janvier 1988 et décembre 2005, sept cas (chez cinq femmes et deux hommes de moyenne d’âge de 75 ans [70—79 ans]), ont fait l’objet d’une arthroscopie dans les suites. La fréquence de l’arthroscopie après prothèse unicompartimentale était de 3,3 %. L’indication était posée devant la persistance de la douleur, 16,3 mois après la pose de la prothèse unicompartimentale (min 9—max 36 mois). Les sept patients étaient évalués cliniquement et radiologiquement avec un recul moyen de trois ans (12 mois à cinq ans) après l’arthroscopie. L’intérêt de l’arthroscopie pour le diagnostic et/ou le traitement de ces gonalgies après prothèse unicompartimentale, inexpliquées par les examens complémentaires non invasifs traditionnels, est retrouvé dans les sept observations. L’étiologie de ces douleurs peut ainsi être rattachée à une lésion méniscale dans le compartiment non prothésé, à un néoménisque ou un ménisque insuffisamment réséqué dans le compartiment prothésé, à une interposition fibreuse ou encore un fragment de ciment. L’arthroscopie, après prothèse unicompartimentale du genou douloureux, donne souvent de bons résultats dans les douleurs inexpliquées. Le score IKS genou a gagné 13 points après arthroscopie et le score fonction a gagné 20 points. Elle a, dans cette série, permis de trouver une cause à ces douleurs du genou après prothèse unicompartimentale, et souvent, malgré deux échecs, de la traiter

Relationship between the surgical epicondylar axis and the articular surface of the distal femur: an anatomic study

Many authors presented the epicondylar axis as the fixed axis of rotation of the femoral condyles during flexion of the knee. Positioning of the femoral component of a total knee arthroplasty (TKA) based on the epicondyles has been proposed. This work is a critical analysis of this concept. Metallic bodies were inserted at the level of collateral ligament insertions on 16 dried femurs, allowing us to locate the surgical epicondylar axis. The dried femurs were studied using standard radiographs and CT-scan. CT cuts were made perpendicular to the epicondylar axis. The medial mechanical femoral angle and the epicondylar angle were measured on the radiographs. The posterior and distal epiphyseal rotations relative to the epicondylar axis (Posterior Condylar Angle, PCA, and Distal Condylar Angle, DCA, respectively) were measured on the CT-scans. PCA and DCA values were compared. The centre of the posterior femoral condyles was located on sagittal reconstructions using the tangent method and was confirmed with circular templates, and then compared to the location of the epicondyles. Circle-fitting of the entire femoral condylar contours centred on the epicondyles was also tried. The mechanical femoral axis was nearly perpendicular to the epicondylar axis but with important variations. The average PCA and DCA were 1.9 ± 1.8 and 3.1 ± 2.1, respectively. No relationship could be established between the mechanical femoral angle and the PCA. The individual differences between the PCA and the DCA averaged 2.2. A significant distance was found between the centre of the condylar contours and the epicondyles: 6.5 mm in average on the lateral side (range 2.3–11.3 mm) and 8.4 mm on the medial side (range 4.0– 11.6 mm). Circle-fitting of the entire medial or lateral femoral condylar contours centred on the epicondyles was not possible. The centre of the posterior femoral condyles is significantly different from the epicondylar axis, thus refuting the conclusions of previous authors. Furthermore, considering the differences between the distal and posterior condylar angles shown here, as well as the difficulty of repeatably locating the epicondyles during surgery, using the epicondylar axis as the only landmark to position the femoral component during a first intention TKA is not recommended. The surgical epicondylar axis does not appear to be an adequate basis for the understanding of the shape of the distal femur

Conservative Femoral Stem Revision: Avoiding Therapeutic Escalation

A conservative approach to femoral revision is assessed. We report on 41 femoral revisions using an extensively coated hydroxyapatite primary femoral stem. Clinical, operative, and radiological data were gathered. Harris hip scores increased from 65/100 to 90/100 at the minimal follow-up of 1 year (P < .05). All stems showed signs of osseous integration. No significant migration was measured. No patient had to be reoperated because of problems related to the stem. Good results are reported for femoral revision with Paprosky type I and II bone defects with no significant difference between the 2 subgroups, hereby proving that conservative femoral revision is a reasonable treatment alternative. Reproducible results with such a technique may bring surgeons to be more aggressive when noticing early signs of femoral loosening

The influence of femoral cementing on perioperative blood loss in total knee arthroplasty a prospective randomized study

Background: Total knee arthroplasty can involve substantial blood loss. We prospectively studied a consecutive series of patients undergoing primary total knee arthroplasty to assess the influence of femoral cementing on perioperative blood loss. We hypothesized that an uncemented femoral component is a risk factor for bleeding. Methods: A semiconstrained posterior stabilized prosthesis was used in all patients. Preoperatively, 130 patients were randomly assigned to either the cement group (Group 1) or the hybrid group (Group 2). We selected all patients who underwent a knee replacement through a medial parapatellar approach (n = 107). Group 1 consisted of forty-two women and twelve men ranging in age from fifty-six to eighty-five years. Group 2 consisted of thirty-seven women and sixteen men ranging in age from fifty-six to eighty-five years. The hemoglobin and hematocrit levels were recorded preoperatively and five days postoperatively for each patient. The volumes of postoperative suction drainage and the rate of blood transfusion were recorded. Results: No differences between the two groups were identified with regard to hemoglobin and hematocrit levels, total measured blood loss, postoperative drainage amounts, or transfusion rates. The total measured blood loss was 1758.9 mL for Group 1 and 1759 mL for Group 2. Conclusions: Cementing the femoral component during a total knee arthroplasty does not appear to influence the amount of perioperative blood loss or the need for postoperative blood transfusion

Long-Term Follow-Up of 24.5 Years After Intra-Articular Anterior Cruciate Ligament Reconstruction With Lateral Extra-Articular Augmentation

Background: Many studies have reported successful outcomes 10 to 15 years after ACL reconstruction. However, few authors report results at ultra long-term follow-up (more than 20 years of follow-up). Purpose: The aim of this study was to determine how the status of the medial meniscus and the medial compartment articular cartilage observed at the time of ACL reconstruction affects results more than 24 years after surgery. This article examines longterm outcome of ACL reconstruction with extra-articular augmentation (procedure performed through a medial arthrotomy). Study Design: Case series; Level of evidence, 4. Methods: One hundred of 148 patients reviewed at 11.5 years of follow-up could be reviewed at 24.5 years. Complete clinical and radiographic evaluation (International Knee Documentation Committee scale and Knee Injury and Osteoarthritis Outcome Score) was performed. Results: The radiographic International Knee Documentation Committee rating was as follows: grade A, 39%; grade B, 7%; grade C, 27%; and grade D, 27%. Onset of osteoarthritis was correlated with medial meniscal status and femoral chondral defects at time of surgery. Conclusion: Total medial meniscectomy and articular cartilage damage were risk factors for osteoarthritis