Guillaume Demey

In Vivo Positioning Analysis of Medial Patellofemoral Ligament Reconstruction

Background: Several techniques have been described for reconstruction of the medial patellofemoral ligament (MPFL). The anatomical insertion of the MPFL has been defined; however, there are no reports describing the accuracy of femoral graft positioning assessed postoperatively. Purpose: To analyze our femoral tunnel positioning for MPFL reconstruction in correlation with our clinical results. Study Design: Case series; Level of evidence, 4. Methods: The authors reported a prospective series of 29 MPFL reconstructions with a minimum follow-up of 24 months. The tunnel positioning analysis was performed using plain radiographs and magnetic resonance imaging at 1-year follow-up. Results: Twenty-nine femoral tunnels were analyzed; 20 femoral tunnels (69%) were considered to be in good position on plain radiographs. On magnetic resonance imaging, the authors found 19 femoral tunnels (65%) in a proper location, 5 (17.5%) in a high position, and 5 in an anterior and/or high position. Conclusion: The study highlights the difficulty of reproducible MPFL reconstruction. The surgical procedure continues to be improved and finding a reliable technique to anatomically place the graft remains challenging. Verifying femoral tunnel placement radiographically may be recommended during surgery.

Patellar Tendon Tenodesis in Association With Tibial Tubercle Distalization for the Treatment of Episodic Patellar Dislocation With Patella Alta

Background: The association between patella alta and episodic patellar dislocation (EPD) has been well described, but its pathophysiology is not completely clear. Patella alta causes decreased contact between the patella and trochlea and decreased resistance to lateral translation of the patella. Additionally, increased patellar tendon length may allow pathologically increased coronal plane patellar motion. It may thus be desirable to address the length of the patellar tendon itself rather than just its insertion site. Hypothesis: Tenodesis of the patellar tendon in association with tibial tubercle distalization in patients with EPD and abnormally long patellar tendons (>52 mm) results in significant reduction in patellar tendon length, prevention of further patellar dislocation, and good knee function at long-term follow-up. Study Design: Case series; Level of evidence, 4. Methods: Twenty-seven knees in 22 patients with EPD and patella alta were treated with patellar tendon tenodesis and tibial tubercle distalization. Following tubercle distalization, the patellar tendon was tenodesed into the original location of the tibial tubercle with suture anchors. Changes in patellar tendon length and patellar height were measured radiographically. Any recurrent dislocation was documented, and patients completed an International Knee Documentation Committee (IKDC) subjective form at a mean of 9.6 years (range, 6-14 years) after surgery. Results: The mean length of the patellar tendon decreased from 56.3 ± 2.7 mm to 44.3 ± 8.6 mm (P < .0001). The Caton-Deschamps index decreased from 1.22 ± 0.17 to 0.95 ± 0.22 (P < .0001), and the Insall-Salvati ratio decreased from 1.42 ± 0.17 to 0.91 ± 0.18 (P < .0001). No patellar dislocations occurred postoperatively. The mean postoperative subjective IKDC score was 75.6 ± 9.5. Conclusion: Patellar tendon tenodesis and tibial tubercle distalization result in normalization of patellar tendon length, a stable patellofemoral joint, and good long-term knee function in patients with patella alta and EPD.

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.

Does a Collar Improve the Immediate Stability of Uncemented Femoral Hip Stems in Total Hip Arthroplasty? A Bilateral Comparative Cadaver Study

The aim of this study was to compare the immediate stability of collared vs collarless uncemented femoral stems in total hip arthroplasty. A bilateral comparative study of 20 cadavers (40 hips: 20 collarless, 20 collared) was performed. Forces in the vertical and horizontal planes required to initiate subsidence of femoral stem and subsequent femoral fracture were measured. In vertical plane, subsidence began at an average force of 3129 ± 494 N for collarless stems and 6283 ± 3584 N for collared stems (P = .02). Fracture occurred at a significantly higher force for collared stems (P = <.001). In horizontal plane, subsidence began at an average force of 540 ± 170 N for collarless stems and 678 ± 206 N for collared stems (P = .01). Fracture occurred at a significantly higher force for collared stems (P = .005). Collared uncemented stems have significantly greater immediate stability than collarless. They are able to withstand greater vertical and horizontal forces before the initiation of subsidence and subsequent fracture.

The Effect of Medial Opening and Lateral Closing High Tibial Osteotomy on Leg Length

Background: High tibial osteotomy (HTO) is a common treatment for medial compartment arthritis of the knee in younger, more active patients. An HTO also potentially affects leg length. Mathematical models predict that the osteotomy type (medial opening-wedge vs lateral closing-wedge) and the magnitude of the correction determine the change in leg length, but no in vivo studies have been published. Purpose: This study was undertaken to quantify and compare leg-length change after opening-wedge and closing-wedge HTO. Study Design: Cohort study; Level of evidence, 3. Methods: Thirty-two medial opening-wedge and 32 lateral closing-wedge HTOs were selected from patients treated at the authors’ institution. Preoperative and postoperative coronal plane alignment and leg length were measured and surgical details were collected. Results: The 64 osteotomies were performed at an average age of 57 years. The mean opening wedge was 9.3 mm and the mean closing wedge was 8.0 mm. Mean knee alignment changed from 174° preoperatively to 183° postoperatively in both groups. In the medial opening-wedge group, entire leg length changed from 836.3 ± 63.5 mm to 841.8 ± 64.1 mm, an increase of 5.5 ± 4.4 mm (P < .0001). Tibia length changed from 368 ± 30.9 mm to 372.3 ± 31.2 mm, an increase of 4.3 ± 2.3 mm (P < .0001). In the lateral closing-wedge group, entire leg length changed from 840.6 ± 51.5 mm preoperatively to 837.9 ± 52.0 mm postoperatively, a decrease of 2.7 ± 4.0 mm (P = .0008). Tibia length changed from 365.1 ± 23.2 mm to 361 ± 22.9 mm, a decrease of 4.1 ± 2.9 mm (P < .0001). The difference in mean leg-length change between opening-wedge and closing-wedge osteotomies was 8.2 ± 5.9 mm (P < .0001). Conclusion: Both medial opening-wedge and lateral closing-wedge HTO can result in significant leg-length change, but changes are generally less than mathematical models predict.

A CT-based classification of prior ACL femoral tunnel location for planning revision ACL surgery

PurposeThe purposes of this study are to describe an ACL femoral tunnel classification system for use in planning revision ACL reconstruction based on 3-D computed tomography (CT) reconstructions and to evaluate its inter- and intra-rater reliability.MethodsA femoral tunnel classification system was developed based on the location of the femoral tunnel relative to the lateral intercondylar ridge. The femoral tunnel was classified as Type I if it was located entirely below and posterior to the ridge as viewed from distally, Type II if it was slightly malpositioned (either vertically, anteriorly, or both), and Type III if it was significantly malpositioned. To evaluate the reproducibility of the classification system, CT scans of 27 knees were obtained from patients scheduled for revision ACL reconstruction, and 3-D reconstructions were created. Four views of the 3-D reconstruction of each femur were then obtained, and inter- and intra-observer reliability was determined following classification of the tunnels by eight observers.ResultsTwenty-five tunnels were classified as Type I (5 tunnels), Type II (9 tunnels), or type III (11 tunnels) by at least 5 of 8 observers, while insufficient agreement was noted to classify two tunnels. The interobserver reliability of tunnel classification as type I, II, or III yielded a κ coefficient of 0.57, while intra-observer reliability yielded a κ coefficient of 0.67. Subclassification of type II femoral tunnels into the subgroups anterior, vertical, and both was possible in four of the nine type II patients. The interobserver reliability of the complete classification system yielded a κ coefficient of 0.50, while the intra-observer reliability yielded a κ coefficient of 0.54.ConclusionClassification of the location of ACL femoral tunnels utilizing 3-D reconstructions of CT data yields moderate to substantial inter- and intra-observer reliability.Level of evidenceDiagnostic Level III.

Treatment of chronic disruption of the patellar tendon in Osteogenesis Imperfecta with allograft reconstruction

We present a case of chronic disruption of the patellar tendon in a patient with Osteogenesis Imperfecta. This patient was treated with a customized extensor mechanism allograft. Results were excellent at 5 years follow up. To our knowledge this treatment has not previously been published in this situation. We present this as a reliable treatment option.

The effect of gender on outcome of unicompartmental knee arthroplasty

No report has specifically addressed the question of the influence of gender on outcome following unicompartmental knee arthroplasty (UKA). To clarify this issue, we studied two groups of 40 patients of each gender, matched by pre-operative clinical and radiological presentation, and with post-operative follow up of at least 2 years. The mean age at operation was 71 years and the mean follow-up was 5.9 years. In both groups, IKS score improved significantly, but without difference based on gender. No difference was found between groups in terms of range of motion, alignment, or radiologic progression of arthritis. These results suggest that when utilizing specific patient selection criteria, gender does not influence outcome following UKA.

Evolution of trochlear compartment geometry in total knee arthroplasty

BACKGROUND The study aimed to compare trochlear profiles in recent total knee arthroplasty (TKA) models and to determine whether they feature improvements compared to their predecessors. The hypothesis was that recent TKA models have more anatomic trochlear compartments and would display no signs of trochlear dysplasia. METHODS The authors analyzed the geometry of the 6 following TKA models using engineering software: PFC and Attune (DePuy), NexGen and Persona (Zimmer), Noetos and KneeTec (Tornier). The mediolateral trochlear profiles were plotted at various flexion angles (0°, 15°, 30° and 45°) to deduce the sulcus angle. RESULTS Analysis of sulcus angles reveals general convergence of recent designs towards anatomic values. At 0° of flexion, sulcus angles of recent implant models were between 156.0-157.4°, while those of previous generation models between 154.5-165.5°. At 30° of flexion, sulcus angles of recent models also lie within 145.7-148.6°, but those of previous models are between 149.5-152.0°. All three manufacturers deepened their trochlear profile at 30° of flexion in recent models compared to earlier designs. Sulcus angles converge towards anatomic values but still exceed radiologic signs of dysplasia by 2-5°. CONCLUSIONS Recent TKA designs have more anatomic trochlear geometries than earlier TKA models by the same manufacturers, but trochlear compartments still exceed radiologic signs of trochlear dysplasia by 2° to 5°. The hypothesis that recent TKA models display no signs of trochlear dysplasia is therefore refuted. Surgeons should be aware of design limitations to optimize choice of implant and extensor mechanisms alignment. LEVEL OF EVIDENCE IV geometric implant analysis.

Total knee arthroplasty for secondary osteoarthritis following ACL reconstruction: A matched-pair comparative study of intra-operative and early post-operative complications

Injury to the anterior cruciate ligament (ACL) is associated with increased risk of osteoarthritis and subsequent need for total knee arthroplasty (TKA). The impact of prior ACL reconstruction on TKA has been rarely studied. Twenty-two patients undergoing TKA, with a mean of 26 years following ACL reconstruction, were compared to a matched control group. Tibial exposure was more difficult in the study group, requiring tibial tubercle osteotomy in three cases (14%). Manipulation under anesthesia was required in five patients in the study group (23%) and none in the control group (p=0.048). No differences in final range of motion, outcomes scores, or alignment were noted 2 to 3 year post-operative. Total knee arthroplasty following ACL reconstruction is effective. Difficulties in obtaining tibial exposure and post-operative stiffness requiring manipulation under anesthesia are common.