Posterior Condyle Research Articles

A clinical study of the rotational alignment of the femoral component in total knee arthroplasty.

[Purpose] The reasons for femorotibial rotational malalignment after total knee arthroplasty (TKA) were analyzed to provide evidence for clinical knee joint surgery and to reduce complications. [Subjects and Methods] Ninety knees of 60 patients were selected and randomly divided into two groups (n=30). For one group, rotational alignment of the femoral component was determined by the transepicondylar axis and TKA was performed. For the other group, rotational alignment of the femoral component was conducted through 3° external rotation of the posterior femoral condyles. Knee joint specimens were operated with TKA and various biomechanical indices were measured. [Results] The femoral epicondylar axis was a constant, reliable reference for femoral component rotational alignment. When the femoral component was rotated by 0° versus the epicondylar axis, the peak contact pressure on the patellofemoral joint was optimal. When the femoral component was arranged in parallel with Whiteside’s line, the peak contact pressure on the patellofemoral joint varied largely. The patellofemoral contact areas of the two groups were similar. [Conclusion] Axial rotational alignment of the femoral component influenced the contact pressure of patellofemoral joints in TKA more significantly than external rotation of the femoral condyles. It is more reliable to use the femoral epicondylar axis as the reference for the rotational alignment of the femoral component.

Knee joint loading during lineman-specific movements in American football players.

Linemen are at high risk for knee cartilage injuries and osteoarthritis. High-intensity movements from squatting positions (eg, 3-point stance) may produce high joint loads, increasing the risk for cartilage damage. We hypothesized that knee moments and joint reaction forces during lineman-specific activities would be greater than during walking or jogging. Data were collected using standard motion analysis techniques. Fifteen NCAA linemen (mean ± SD: height = 1.86 ± 0.07 m, mass = 121.45 ± 12.78 kg) walked, jogged, and performed 3 unloaded lineman-specific blocking movements from a 3-point stance. External 3-dimensional knee moments and joint reaction forces were calculated using inverse dynamics equations. MANOVA with subsequent univariate ANOVA and post hoc Tukey comparisons were used to determine differences in peak kinetic variables and the flexion angles at which they occurred. All peak moments and joint reaction forces were significantly higher during jogging than during all blocking drills (all P < .001). Peak moments occurred at average knee flexion angles > 70° during blocking versus < 44° in walking or jogging. The magnitude of moments and joint reaction forces when initiating movement from a 3-point stance do not appear to increase risk for cartilage damage, but the high flexion angles at which they occur may increase risk on the posterior femoral condyles.

Radiographic Anatomy of the Native Anterior Cruciate Ligament: a Systematic Review.

In an attempt to improve the accuracy and reproducibility of tunnel positioning, radiographs are being analyzed in an attempt to recreate the native anatomy of the ACL. Understanding the native ACL radiographic anatomy is an essential prerequisite to understand the relevance of postoperative tunnel position. We performed a systematic review of the literature to delineate the radiographic location of the native ACL femoral and tibial footprints. A search was performed in March 2014 in PubMed, the Cochrane Collaboration Library, and EMBASE to identify all studies that evaluated the native anterior cruciate ligament (ACL) anatomy on radiographs. Various measurement methods were used in each study, and averages were obtained of the data from studies with the same measurement methods. Fifteen papers were identified (which included data on 177 femora and 207 tibiae in total). Evaluation of the femoral footprint using the quadrant method on lateral knee radiographs showed that the average percent distance location of the anteromedial (AM) bundle and posterolateral (PL) bundle was 22.8% (95% confidence interval (CI) 16.59-28.90) and 32.5% (95% CI 27.71-37.26) from the posterior condyle, respectively, and 23.2% (95% CI 19.52-26.94) and 50.0% (95% CI 46.16-53.76) from Blumensaat's line, respectively. Using the Amis and Jacob method, the tibial footprint on the lateral knee radiograph average percent distances was 35.1% (95% CI 34.46-35.72) for the center of the AM bundle and 47.3% (95% CI 41.69-52.95) for the center of the PL bundle of the ACL. The femoral and tibial ACL footprints on the anteroposterior (AP) views of the knee were not well delineated by these studies. The information presented in this systematic review offers surgeons another important tool for accurate ACL footprint identification.

Evaluation of posterior lateral femoral condylar hypoplasia using axial MRI images in patients with complete discoid meniscus.

Hypoplasia of the lateral femoral condyle has been reported in discoid lateral meniscus patients, but associated imaging findings in the axial plane have not been characterized. In this study, we aimed to identify differences in the lateral femoral condyle between patients with discoid lateral meniscus and those with normal menisci using axial MRI images. Twenty-three patients (24 knees) with complete discoid lateral meniscus, 43 (45 knees) with incomplete discoid lateral meniscus, and 50 with normal menisci (50 knees) were enrolled and distributed into three groups. Two new angles, posterior lateral condylar angle (PLCA) and posterior medial condylar angle (PMCA), were measured on axial MRI images; the posterior condylar angle (PCA) was also measured. Differences between the three groups in the PLCA, PMCA, PCA, and PLCA/PMCA were analysed. The predictive value of PLCA and PLCA/PMCA for complete discoid lateral meniscus was assessed. In the complete discoid lateral meniscus group, PLCA and PLCA/PMCA were significantly smaller compared with the normal meniscus group and the incomplete discoid lateral meniscus group (P<0.001). A significantly larger PCA was identified in the complete discoid lateral meniscus group compared with the incomplete discoid lateral meniscus group (P<0.05) and normal meniscus group (P<0.05). Both PLCA and PLCA/PMCA showed excellent predictive value for complete discoid lateral meniscus. Hypoplasia of the posterior lateral femoral condyle is typically seen in patients with complete discoid lateral meniscus. PLCA and PLCA/PMCA can be measured from axial MRI images and used as excellent predictive parameters for complete discoid lateral meniscus. Diagnostic study, Level III.

Cartilage thickness at the posterior medial femoral condyle is increased in femorotibial knee osteoarthritis: a cross-sectional CT arthrography study (Part 2)

To evaluate the thickness of cartilage at the posterior aspect of the medial and lateral condyle in Osteoarthritis (OA) knees compared to non-OA knees using computed tomography arthrography (CTA). 535 consecutive knee CTAs (mean patient age = 48.7 ± 16.0; 286 males), were retrospectively analyzed. Knees were radiographically classified into OA or non-OA knees according to a modified Kellgren/Lawrence (K/L) grading scheme. Cartilage thickness at the posterior aspect of the medial and lateral femoral condyles was measured on sagittal reformations, and compared between matched OA and non-OA knees in the whole sample population and in subgroups defined by gender and age. The cartilage of the posterior aspect of medial condyle was statistically significantly thicker in OA knees (2.43 mm (95% confidence interval (CI) = 2.36, 2.51)) compared to non-OA knees (2.13 mm (95%CI = 2.02, 2.17)) in the entire sample population (P < 0.001), as well as for all subgroups of patients over 40 years old (all P ≤ 0.01), except for females above 60 years old (P = 0.07). Increase in cartilage thickness at the posterior aspect of the medial condyle was associated with increasing K/L grade in the entire sample population, as well as for males and females separately (regression coefficient = 0.10-0.12, all P < 0.001). For the lateral condyle, there was no statistically significant association between cartilage thickness and OA (either presence of OA or K/L grade). Cartilage thickness at the non-weight-bearing posterior aspect of the medial condyle, but not of the lateral condyle, was increased in OA knees compared to non-OA knees. Furthermore, cartilage thickness at the posterior aspect of the medial condyle increased with increasing K/L grade.

Will a single periarticular lidocaine-corticosteroid injection improve the clinical efficacy of intraarticular hyaluronic acid treatment of symptomatic knee osteoarthritis?

A local injection of corticosteroid-lidocaine into the periarticular soft tissue structures is used commonly for rapid pain relief. It is hypothesized that knee pain associated with knee osteoarthritis would be relieved quickly and effectively in patients receiving intraarticular hyaluronic acid combined with a periarticular lidocaine-corticosteroid injection. To test this hypothesis, the clinical effect of the combined treatment with hyaluronic acid injection alone in patients with symptomatic knee osteoarthritis as compared in this prospective single-blinded randomized trial. This study included 70 patients. Group 1 (n=35) received intraarticular hyaluronic acid injections only, whereas group 2 (n=35) received intraarticular hyaluronic acid injections combined with a single local injection of corticosteroid-lidocaine. Injections were administered to the most painful areas of the anterior or posterior medial condyle of the femur or tibia. The outcome was measured by independent assessors (blinded to treatment) using a linear VAS pain scale and WOMAC and HSS knee scores. Assessments were performed at baseline and at 1, 3, 6, 12, 26, and 52weeks. During the first 3weeks, group 2 patients showed significantly better all scores than did group 1 patients (p<0.01). However, no significant differences were detected at 6, 12, 26 or 52weeks (n.s.). The combined treatment may lead to earlier pain relief compared with intraarticular hyaluronic acid alone in patients with knee osteoarthritis and can be considered a useful adjunctive treatment modality. This combined method may provide early return to patient's daily activity. Therapeutic study, Level I.

Correlation Between Asymmetric Resection of Posterior Femoral Condyles and Femoral Component Rotation in Total Knee Arthroplasty

Objectives:Pertaining to peculiar designs of current knee prostheses, more bone is removed from posteromedial femoral condyle than posterolateral condyle to obtain desired femoral component rotation. The aim of our study was to evaluate whether there is a correlation between the asymmetry of the cuts and the femoral component rotation in total knee arthroplasty.Methods:We built a model to simulate anterior chamfer cut (ACC) performed during total knee arthroplasty for measuring posterior condylar offset (PCO). Right knee axial MRI slices of a total 290 consecutive patients (142 male, 138 female, and mean age 31.39 ± 6.6) were examined. A parallel line to surgical transepiphyseal axis was drawn, and placed at the deepest part of trochlear groove. Posteromedial and posterolateral condylar offsets were measured by drawing perpendicular lines to ACC beginning from the intersection points of both anteromedial and anterolateral cortices to posterior joint line (PJL), respectively. Differences between posteromedial and posterolateral PCO were calculated, and femoral rotation angles (FRA) relative to PJL were measured.Results:The mean surgical FRA was 4.76 ± 1.16 degrees and the mean PCO differencesss- was 4.35 ± 1.04 mm for the whole group and there was no statistically significant difference between genders. There was a strong correlation between surgical FRA and PCO difference (p<0.0001, r=0.803). Linear regression analyses revealed that 0.8 mm of difference between the anteroposterior dimensions of medial and lateral PCO corresponds to 1 degree of surgical FRA (p<0.0001, R2=0.645).Conclusion:Correlation between the asymmetry of posterior chamfer cuts and achieved femoral component rotation can verify the accuracy of desired rotation, intraoperatively. However, further clinical investigations should be planned to test the results of our morphometric study.

Anterior tibial plateau fracture: An often missed injury.

Background:In most classifications of tibial plateau fractures, including one used most widely-Schatzker classification, fractures are described as a combination of medial and lateral condyle, primarily in the sagittal plane. Coronal component of these fractures, affecting the posterior tibial condyle is now well recognized. What is not described is anterior coronal component of the fracture, what we are calling “anterior tibial condyle fracture”. These fractures are often missed on routine antero-posterior and lateral knee X-rays due to an overlap between the fracture and the normal bone.Materials and Methods:Eight cases of anterior tibial condyle fractures with posterior subluxation of the tibia, six of which were missed by the initial surgeon and two referred to us early, are described. Two of the six late cases and both the early ones were operated. Reconstruction of the anterior condyle and posterior cruciate ligament reconstruction was done. Primary outcome measures such as union of the fracture, residual flexion deformity, range of motion and stability were studied at the end of 6 months.Results:All operated fractures united. There was no posterior sag in any. In those presenting late and were operated, the flexion deformity got corrected in all (average from 15° to 0°) and mean flexion achieved was 100° (range: 80-120°). In those presenting early and were operated, there was no flexion deformity at 6 months and a mean flexion achieved was 115° (range: 100-130°). None of the operated patients had instability.Conclusion:This article attempts to highlight that this injury is often missed. They should be suspected, diagnosed early and treated by reconstruction of anterior condyle, posterior cruciate ligament reconstruction.

Radiographic landmarks for surgical reconstruction of the anterolateral ligament of the knee.

To determine the radiographic landmarks of the anterolateral ligament (ALL) on the femur and tibia to assist in intraoperative graft placement during ALL reconstruction. The footprints of the ALL, fibular collateral ligament (FCL), popliteus insertion, lateral gastrocnemius insertion, and Gerdy's tubercle were isolated and centrally marked with tantalum beads in thirteen fresh-frozen cadaveric knees. Measurements were taken from the true lateral fluoroscopic images. On the femur, the mean distances from the ALL origin to the FCL origin and from the ALL origin to the popliteus insertion were measured. On the tibia, the mean distances from the ALL insertion to Gerdy's tubercle and from the ALL insertion to the lateral tibial plateau were measured. Furthermore, radiographic descriptions of the ALL origin and insertion were developed. The ALL origin on the femur averaged 3.3 ± 1.5 mm anterior-distal to the FCL origin in one anatomical variant and 5.4 ± 1.4 mm posterior-proximal to the FCL origin in a second variant. The ALL origin was 9.9 ± 2.7 mm from the popliteus insertion. The ALL origin is described as overlying the posterior femoral cortical line, between Blumensaat's line and a line from the posterior condylar articular edge parallel to Blumensaat's line. The ALL insertion on the tibia averaged 24.7 ± 4.5 mm posterior to Gerdy's tubercle and 11.5 ± 2.9 mm distal to the lateral tibial plateau. The tibial ALL insertion is described between the posterior tibial cortical line and a parallel line drawn down from the apex of the tibial spine, and overlying a line drawn perpendicular to the posterior tibial cortical line starting from the apex of the posterior tibial condyles. Using direct lateral fluoroscopy, radiographic landmarks of the ALL origin and insertion have been described.

AB0789 The Clinical Effects of Post-Operative Anterior-Posterior Length Mismatch in Distal Femur with after Total Knee Arthroplasty

BackgroundRecently, anatomic differences of the distal femur in gender and races were reported. Especially in total knee arthroplasty (TKA), relationship between the anterior-posterior (AP) length and the medial-lateral width of...

Quantitative Magnetic Resonance Imaging UTE-T2* Mapping of Cartilage and Meniscus Healing After Anatomic Anterior Cruciate Ligament Reconstruction

Background: An anterior cruciate ligament (ACL) injury greatly increases the risk for premature knee osteoarthritis (OA). Improved diagnosis and staging of early disease are needed to develop strategies to delay or prevent disabling OA. Purpose: Novel magnetic resonance imaging (MRI) ultrashort echo time (UTE)–T2* mapping was evaluated against clinical metrics of cartilage health in cross-sectional and longitudinal studies of human participants before and after ACL reconstruction (ACLR) to show reversible deep subsurface cartilage and meniscus matrix changes. Study Design: Cohort study (diagnosis/prognosis); Level of evidence, 2. Methods: Forty-two participants (31 undergoing anatomic ACLR; 11 uninjured) underwent 3-T MRI inclusive of a sequence capturing short and ultrashort T2 signals. An arthroscopic examination of the medial meniscus was performed, and modified Outerbridge grades were assigned to the central and posterior medial femoral condyle (cMFC and pMFC, respectively) of ACL-reconstructed patients. Two years after ACLR, 16 patients underwent the same 3-T MRI. UTE-T2* maps were generated for the posterior medial meniscus (pMM), cMFC, pMFC, and medial tibial plateau (MTP). Cross-sectional evaluations of UTE-T2* and arthroscopic data along with longitudinal analyses of UTE-T2* changes were performed. Results: Arthroscopic grades showed that 74% (23/31) of ACL-reconstructed patients had intact cMFC cartilage (Outerbridge grade 0 and 1) and that 90% (28/31) were Outerbridge grade 0 to 2. UTE-T2* values in deep cMFC and pMFC cartilage varied significantly with injury status and arthroscopic grade (Outerbridge grade 0-2: n = 39; P = .03 and .04, respectively). Pairwise comparisons showed UTE-T2* differences between uninjured controls (n = 11) and patients with arthroscopic Outerbridge grade 0 for the cMFC (n = 12; P = .01) and arthroscopic Outerbridge grade 1 for the pMFC (n = 11; P = .01) only and not individually between arthroscopic Outerbridge grade 0, 1, and 2 of ACL-reconstructed patients (P > .05). Before ACLR, UTE-T2* values of deep cMFC and pMFC cartilage of ACL-reconstructed patients were a respective 43% and 46% higher than those of uninjured controls (14.1 ± 5.5 vs 9.9 ± 2.3 milliseconds [cMFC] and 17.4 ± 7.0 vs 11.9 ± 2.4 milliseconds [pMFC], respectively; P = .02 for both). In longitudinal analyses, preoperative elevations in UTE-T2* values in deep pMFC cartilage and the pMM in those with clinically intact menisci decreased to levels similar to those in uninjured controls (P = .02 and .005, respectively), suggestive of healing. No decrease in UTE-T2* values for the MFC and new elevation in UTE-T2* values for the submeniscus MTP were observed in those with meniscus tears. Conclusion: This study shows that novel UTE-T2* mapping demonstrates changes in cartilage deep tissue health according to joint injury status as well as a potential for articular cartilage and menisci to heal deep tissue injuries. Further clinical studies of UTE-T2* mapping are needed to determine if it can be used to identify joints at risk for rapid degeneration and to monitor effects of new treatments to delay or prevent the development of OA.

Osteochondral transplantation for the treatment of osteochondral defects at the talus with the Diamond twin system® and graft harvesting from the posterior femoral condyles

The aim of this study is to analyze clinical results after osteochondral cylinder transplantation for osteochondral defects at the medial or lateral talar dome using the Diamond twin system (Karl Storz). We hypothesize that grafts harvesting from the posterior femoral condyles are associated with less donor site morbidity than reported by previous studies. We have surgically treated 20 patients with an osteochondral defect of the talus by osteochondral transplantation with the Diamond twin system via an osteotomy of the ankle. The osteochondral cylinders were harvested from the posterior aspects of the femoral condyles of the ipsilateral knee. The defects at donor site were filled with a bone substitute of tricalcium phosphate (Synthricer, Karl Storz). The mean age was 25.4 years. After a mean time of 12.6 months, the screws at the medial malleolus were removed and an arthroscopy was performed. The functional outcome was evaluated with the visual analog scale for pain at walking, running, stair climbing, quality of life at the time of implant removal and at a mean follow-up of 25.8 months. Activity was assessed with the Tegner scale. Knee function was evaluated with the Lysholm score. In one case, the osteochondral cylinder did not heal and an osteochondral fragment was removed arthroscopically. In all other cases, the osteochondral cylinder was stable with surrounding cartilage. The average ICRS Cartilage Repair Assessment was 10.1 points (±1.3). All malleolar osteotomies healed radiologically. In 15 patients, a synovectomy and local debridement of the ankle were performed at second-look arthroscopy. Ankle pain at walking, running and stair climbing as measured by a visual analog scale (10-0) decreased significantly from preoperatively to the first follow-up (mean 12.6 months) and to the second follow-up (mean 25.8 months). The ankle-related quality of life increased significantly from preoperatively to postoperatively. There was no significant change in the Lysholm score. The activity measured with the Tegner activity scale increased significantly from preoperatively to the last follow-up, but only two out of nine patients continued pivoting sports. Autologous osteochondral grafting with the Diamond twin system is a reliable treatment option for symptomatic osteochondral defects of the talus. After 1 year, the majority of patients had still some complaints. However, after screw removal and second-look arthroscopy, the pain and ankle-related quality of life further improved. The donor site morbidity after graft harvesting from the posterior aspects of the femoral condyles is lower than previously reported.

Measured Resection Versus Gap Balancing for Total Knee Arthroplasty

The number of TKAs performed in the United States is expected to increase substantially in the next two decades [6]. Additionally, surgeons are performing TKAs in younger and more active patients. While many articles discuss the importance of radiographic alignment, soft-tissue balancing is essential to a successful TKA. There remains great controversy in how surgeons obtain correct alignment and soft-tissue tensioning. Some surgeons utilize a measured resection technique, while other surgeons favor a gap-balancing technique. As such, I have invited two internationally known orthopaedic surgeons to discuss these two approaches, both of which seek to achieve the same general goal — a well-aligned and well-balanced TKA. Bryan D. Springer MD is an attending joint replacement surgeon at the OrthoCarolina Hip and Knee Center in Charlotte, NC, USA, and a member of The Knee Society. Dr. Springer is the recipient of numerous Knee Society Awards, and has extensive experience with the gap-balancing technique. Sebastien Parratte MD, PhD is an attending joint replacement surgeon and assistant professor of orthopedic surgery at the University Hospital of Marseille in Marseille, France. Dr. Parratte likewise has received numerous Knee Society and Hip Society Awards, and has considerable experience with the measured resection technique. Matthew P. Abdel MD:What do you each see as the advantages of the gap-balancing or measured resection techniques, in terms of achieving ligament balance? Bryan D. Springer MD: Instability following TKA remains one of the most common modes of early failure. The gap-balancing technique is based on the progressive release of ligaments to create equal and symmetric flexion and extension gaps. It is imperative that one understands what structures affect extension, flexion, and both in order to create proper balance. One of the fundamental differences between the gap-balancing technique and measured resection technique lies in setting the rotation of the femoral component to achieve a symmetric flexion gap. Measured resection relies on arbitrary bony landmarks (surgical transepicondylar axis, posterior condylar axis, and anteroposterior (AP) axis of the femur) in order to set rotation. While bony landmarks may occasionally provide accurate rotation of the femoral component, one major disadvantage is the surgeon’s inability to accurately and reproducibly find them intraoperatively. Research has suggested there is wide variability in femoral component rotation when using bony landmarks, which leads to asymmetry of the flexion space and condylar lift off (Fig. 1) in flexion [3]. Open in a separate window Fig. 1 This schematic depicts condylar lift off that occurs when there is asymmetry of the flexion space. Published courtesy of Bryan D. Springer MD.

Anatomical study of the medial patello-femoral ligament: landmarks for its surgical reconstruction

The aim of this dissection study was to describe the anatomical insertions of the medial patello-femoral ligament (MPFL), and to assess its relationship with surrounding structures to improve its surgical reconstruction. Twelve knees (7 cadavers) were included for the study. Measurements and general features of the MPFL were assessed: lengths, widths and insertions. The MPFL was found in all knees, presenting a triangular shape, and extending from the medial part of the patella to its femoral insertion (its length was of 59±6.6mm), distal to the adductor tubercle. The mean femoral insertion of the MPFL was 7.2±2.7mm proximal and 7.4±4.0mm posterior to the medial femoral epicondyle (MFE). It was also at a mean 11±2.8mm distal and 1.3±2.1mm posterior to the adductor tubercle, and 22±6.4mm anterior to the posterior condyle. We did not find any double-bundle organization on the patellar insertion. The width of the MPFL was 8.8±2.9mm at the femoral insertion, 27±5.9mm at the patellar insertion, and 12±3.1mm in the middle of the MPFL. The vastus medialis obliquus was found to be inserted on the superior part of the MPFL. The adductor tubercle appeared to be a better landmark than the MFE for the femoral tunnel positioning during surgical reconstructions of the MPFL because it was easier to identify and its relationship with the femoral insertion of the MPFL was constant (10mm below).

The potential effect of anatomic relationship between the femur and the tibia on medial meniscus tears

The anatomic and the kinematical relationships between the femur and the tibia have been previously examined in both normal and diseased knees. However, less attention has been directed to the effect of these relationships on the meniscal diseases. Therefore, we aimed to investigate the impact of femorotibial incongruence on both lateral and medial meniscal tears. A total of 100 images obtained from MRI of 100 patients (39 males and 61 females) were included in the study. Diameters of the medial and the lateral femoral condyles, thicknesses of the menisci, and diameters of the medial and the lateral tibial articular surfaces were measured. The medial meniscus tear was detected in 40 (40%) patients. However, no lateral meniscus tear was found. Significant relationships were found between the diameters of the posterior medial femoral condyle and the medial tibial superior articular surface and between the diameters of the posterior lateral femoral condyle and the lateral tibial superior articular surface. The mean values for the diameter of the medial condyle of the femur, the lateral condyle of the femur, the medial superior articular surface of the tibia, and the lateral superior articular surface of the tibia were found to be significantly higher in cases with meniscus tear compared to cases without meniscus tear. However, no significant difference was present regarding the thicknesses of the medial and the lateral menisci. A positive relationship between the diameter of the posterior medial femoral condyle and the tibial medial superior articular surface was found in cases with (n=40) (r (2)=0.208, p=0.003) and without tear (n=60) (r (2)=0.182, p=0.001). In addition, a significant positive relationship was found between the diameter of the posterior medial femoral condyle and the medial tibial superior articular surface in cases with and without tear. The impact of femorotibial incongruence on the medial meniscus tear is important for the understanding of the lesions.

Spectrum of T2* values in knee joint cartilage at 3 T: a cross-sectional analysis in asymptomatic young adult volunteers

To establish baseline T2* values in healthy knee joint cartilage at 3 T. Thirty-four volunteers (mean age: 24.6 ± 2.7 years) with no history or clinical findings indicative of any knee joint disease were enrolled. The protocol included a double-echo steady-state (DESS) sequence for morphological cartilage evaluation and a gradient-echo multi-echo sequence for T2* assessment. Bulk and zonal T2* values were assessed in eight regions: posterior lateral femoral condyle; central lateral femoral condyle; trochlea; patella; lateral tibial plateau; posterior medial femoral condyle; central medial femoral condyle; and medial tibial plateau. Statistical evaluation comprised a two-tailed t test and a one-way analysis of variance to identify zonal and regional differences. T2* mapping revealed higher T2* values in the superficial zone in all regions (P values ≤ 0.001) except for the posterior medial femur condyle (P = 0.087), and substantial regional differences demonstrating superior values in trochlear cartilage, intermediate values in patellar and central femoral condylar cartilage, and low T2* values in posterior femoral condylar cartilage and tibial plateau cartilage. Substantial regional differences in T2* measures should be taken into consideration when conducting T2* mapping of knee joint cartilage.

Nontraumatic Fracture of the Femoral Condylar Prosthesis in a Total Knee Arthroplasty Leading to Mechanical Failure

This paper reports a case of fatigue fracture of the femoral component in a cruciate-retaining cemented total knee arthroplasty (TKA). A 64-year-old man had undergone a primary TKA for osteoarthritis 10 years previously at another institution using the PFC-Sigma prosthesis. The patient recovered fully and was back to his regular activities. He presented with a history of sudden onset pain and locking of the left knee since the preceding three months. There was no history of trauma, and the patient was mobilizing with difficulty using crutches. Radiographs revealed fracture of the posterior condyle of the femoral prosthesis. Revision surgery was performed as an elective procedure revealing the broken prosthesis. The TC3RP-PFC revision prosthesis was used with a medial parapatellar approach. The patient recovered fully without any squeal. Mechanical failure of the knee arthroplasty prosthesis is rare, and nontraumatic fracture of the femoral metallic component has not been reported before.

Intra-articular calcifications following arthroscopic ACL reconstruction: prevalence and possible significance

The goal of our study was to determine the frequency of intra-articular calcifications on initial postoperative radiographs following arthroscopic ACL reconstruction, describe their appearance, hypothesize their etiology, and determine their significance. Review of records and post-operative radiographs for individuals undergoing arthroscopic ACL reconstruction at our institution identified 758 knees between November 2002 and April 2010. All patients underwent femoral and tibial tunnel drilling regardless of graft source. All but 23 underwent notchplasty. Intra-articular calcifications on initial postoperative radiographs were observed in 252 knees. The majority of calcifications were curvilinear, paralleling the posterior femoral condyles. Nineteen of the patients with calcifications on initial studies had repeat radiographs within 6years. The calcifications resolved in every case. This study shows that intra-articular calcifications are a common finding on initial post-operative radiographs following ACL reconstruction. We feel they are of doubtful clinical significance, and in our limited experience, they eventually resolve. They should not be confused with chondrocalcinosis or vascular calcification.

How Frequent Is Rotational Mismatch Within 0°±10° in Kinematically Aligned Total Knee Arthroplasty?

Rotational mismatch of the tibial component on the femoral component within 0°±10° is associated with better function after mechanically aligned total knee arthroplasty (TKA). Kinematically aligned TKA has gained interest; however, the percentage of kinematically aligned TKA within 0°±10° is unknown. The authors prospectively followed all patients who underwent TKA for primary osteoarthritis between December 2011 and April 2012 (194 patients, 195 knees). Each underwent kinematically aligned TKA with manual instruments. Aligning the anteroposterior axis of the tibial component parallel to the line that bisects the oval boundary of the lateral tibial condyle set internal/external rotation. Removing bone from the posterior femoral condyles equal in thickness to the femoral component after correction for cartilage wear set internal/external rotation and anteroposterior translation of the femoral component. Rotational mismatch of the tibial component on the femoral component was determined from a computed tomography scan of the knee. Ninety-seven percent of kinematically aligned TKA with fixed-bearing components had a rotational mismatch within 0°±10° (overall range, -11° to 11°). This percentage was higher and the range narrower than the 85% of TKA within 0°±10° and the -14° to 16° range reported for mechanically aligned TKA. The use of manual instruments to kinematically aligned TKA reliably limited rotational mismatch to within 0°±10°, which has been associated with better function.

T2 values of articular cartilage in clinically relevant subregions of the asymptomatic knee

In order for T2 mapping to become more clinically applicable, reproducible subregions and standardized T2 parameters must be defined. This study sought to: (1) define clinically relevant subregions of knee cartilage using bone landmarks identifiable on both MR images and during arthroscopy and (2) determine healthy T2 values and T2 texture parameters within these subregions. Twenty-five asymptomatic volunteers (age 18-35) were evaluated with a sagittal T2 mapping sequence. Manual segmentation was performed by three raters, and cartilage was divided into twenty-one subregions modified from the International Cartilage Repair Society Articular Cartilage Mapping System. Mean T2 values and texture parameters (entropy, variance, contrast, homogeneity) were recorded for each subregion, and inter-rater and intra-rater reliability was assessed. The central regions of the condyles had significantly higher T2 values than the posterior regions (P < 0.05) and higher variance than the posterior region on the medial side (P < 0.001). The central trochlea had significantly greater T2 values than the anterior and posterior condyles. The central lateral plateau had lower T2 values, lower variance, higher homogeneity, and lower contrast than nearly all subregions in the tibia. The central patellar regions had higher entropy than the superior and inferior regions (each P ≤ 0.001). Repeatability was good to excellent for all subregions. Significant differences in mean T2 values and texture parameters were found between subregions in this carefully selected asymptomatic population, which suggest that there is normal variation of T2 values within the knee joint. The clinically relevant subregions were found to be robust as demonstrated by the overall high repeatability.