Posterior Condyle Research Articles

Static patellofemoral alignment in anterior cruciate ligament deficient knees; a retrospective analysis with magnetic resonance imaging

Static patellofemoral alignment in anterior cruciate ligament deficient knees; a retrospective analysis with magnetic resonance imaging

Comparison of medial and lateral posterior femoral condyle articular cartilage wear patterns

BackgroundWhile degenerative changes to the articular cartilage of the anterior and distal portions of the femoral condyles have been well studied in the literature, the changes that occur on the posterior femoral condyle are not as clear. The purpose of this study was to assess the difference in articular cartilage thickness between the medial and lateral posterior femoral condyles in knees undergoing unicompartmental knee arthroplasty. MethodsA retrospective review of prospectively gathered data on 107 consecutive patients undergoing unicompartmental knee arthroplasty performed by a single surgeon was performed. The remaining articular cartilage thickness after resection of the posterior femoral condyle was measured and simple analysis conducted to compare cartilage thickness between medial and lateral posterior femoral condyles. ResultsNinety-two medial unicompartmental arthroplasties and 15 lateral unicompartmental arthroplasties were performed during the 16 month study period. The majority of lateral UKA patients were female and had lower BMI than medial UKA patients. The articular cartilage thickness on the medial posterior femoral condyle was 3 mm ± 1 mm (mean ± standard deviation) and 1 mm ± 1 mm on the lateral side (p-value <0.001). ConclusionsThere is a significant difference in articular cartilage thickness between the medial and lateral posterior femoral condyles in patients undergoing unicompartmental knee arthroplasty. This coincides with a potentially inherently different pattern of articular cartilage degeneration between the medial and lateral compartments of the knee and has implications on implant designs and resurfacing techniques about the knee.

Gender differences in morphology exist in posterior condylar offsets of the knee in Korean population.

This study aimed to analyze the morphometric data from magnetic resonance images of arthritic knees in Korean adults, and to identify the existence of morphological differences of femoral posterior condylar offset (PCO) between genders. The differences in anthropometric PCO data in 975 patients (825 female and 150 male) were evaluated. The distances from the anterior and posterior femoral shaft cortex line to the most posterior femoral condyle tangent line were defined as the anterior-posterior dimension (AP) and the PCO. The PCO ratio (PCOR) was calculated as PCO/AP. The medial PCO was greater than the lateral PCO (26.3 ± 2.2 vs. 24.3 ± 2.3mm, p < 0.01). This difference was observed in both female patients (medial: 26.2 ± 2.2mm vs. lateral: 24.2 ± 2.2mm, p < 0.01) and male patients (medial: 26.8 ± 2.3mm vs. lateral: 24.8 ± 2.4mm, p < 0.01). The medial and lateral PCO values were also greater in male patients than in female ones (p < 0.01). In contrast, PCOR was greater in female patients than in male ones, both in the medial and lateral femoral condyles (p < 0.01). It was shown that medial and lateral PCO and PCOR were asymmetric, and that there was gender difference in Korean population in our study. In addition, our data showed that the PCOR of contemporary TKAs may be small for Asian patients that may not be sufficient to meet the needs of the Korean patient population. These results confirm that a gender-specific femoral component design is necessary to recreate the PCO for male and female Asian populations. Non-consecutive patients, Level III.

Diagnostic Usefullness of Bone Metal Modality Preset in the 3D Anteversion Angle CT

목적: Pelvis 및 hip 질환은 증가하는 추세임에도 불구하고 Anteversion angle CT는(이하 anteversion CT) 아직 생소하기만 하다. 따라서 Anteversion CT를 소개하고, Anteversion CT의 취약한 부분인 Metallic artifact로 인해 각도 측정이 용이하지 않은 환자들에 추가로 재구성 영상을 제공하여 진단적 가치를 확인하고자 하였다. 대상 및 방법: 2017년 11월부터 12월까지 두 달 동안 본원에 입원 및 내원한 정형외과 환자들 중 금속 인공물로 metallic artifact를 유발하는 Anteversion CT를 시행한 환자(총 32명)를 대상으로 하였다. Anteversion의 각도 측정은 현재 두 가지 방법을 사용하고 있는데, 첫 번째는 femoral neck의 MPR 영상에서 골반과의 각도를 재는 방법이다. 이 방법은 환자의 하지 회전각도에 따라 달라질 우려가 있으므로, Knee axial 사진과의 비교를 통해 각도를 측정한다. 두 번째는 VRT 영상에서 posterior condyle을 평행하게 두고 그 가운데에 femoral neck을 두어 그 각도를 재는 방법이다. 금속 인공물이 포함된 환자의 경우 각도 측정이 어렵기 때문에 metallic artifact로 인해 측정이 어려운 환자를 대상으로 추가적인 재구성 영상을 제공하여 각도 측정을 용이하게 하고자 하였다. 영상 평가에는 신뢰도를 높이기 위해 정형외과 전문의 1명, 영상의학과 전문의 2명, Anteversion CT를 접한 경험이 있는 방사선사 5명(총 8명)을 대상으로 Likert(리커트) 5점 척도로 결과를 나타내었다. 결과: 추가로 제공하는 재구성 영상에 대한 리커트 5점 척도 영상 평가에 따른 결과는 Bone metal modality preset 영상에서 매우 좋음 4개, 좋음 4개로 합계 36점, 평균 4.5 점을 받아 가장 높은 점수로 나타났고, BR MIP modality preset 영상에서 좋음 2개, 보통 1개, 나쁨 3개, 매우 나쁨 2개로 합계 18점, 평균 2.25 점을 받아 가장 낮은 점수를 나타냈다. 각도 측정에 용이하다고 판단 된 영상의 공통점은 femoral neck과 posterior condyle이 명확하게 관찰 되는 경우였다. 반대로 점수가 낮았던 영상은 femoral neck과 posterior condyle이 명확하지 않거나, 일정한 기준이 없어 재현성이 확보되지 않은 영상이었다. 결론: Anteversion CT는 HIP, Pelvis CT에 비해 스캔 범위가 커서 피폭이 많지만, 제공할 수 있는 정보가 많아, 근래 증가하는 골반 및 고관절 질환에 다양한 재구성을 통해 진단적 가치를 높일 수 있다. 고액의 소프트웨어인 MAR(metal artifact reduction)을 구비하지 못한 병원에서도 metallic artifact의 영향이 적으면서 진단적 가치가 높은 Bone metal modality preset 영상을 재구성해 진료에 제공하고, 이외에도 또 다른 modality preset 혹은 방법들이 논의되어 서로 공유할 수 있기를 희망한다.Purpose: Many people do not know about Anteversion angle CT despite trends in increasing pelvic and hip disease. It is not easy to check the angle from Anteversion CT with metallic artifact. so, diagnostic value will be confirmed by adding reconstructed VRT images. Material and methods: The subject of this study is orthopedic patients(sum 32)ordered Anteversion CT with metallic artifact. There are two methods of Anteversion angle measurement. The first method is to measure the angle of the pelvis and Femoral neck in the MPR images. The second method is to measure the angle of the Feomral neck between the parallel posterior condyles in the VRT image. For the purpose of evaluating the images, one orthopedic surgeon and two radiology specialist and five radiologist were evaluated on a Likert scale 5 scale. Result: As a result of Likert scale for the purpose of evaluation about provided images, Bone metal modality preset images received the highest score with sum 36 and average 4.5. and BR MIP modality preset images received the lowest score with sum 18 and average 2.25. Femoral neck and posterior condyles were observed in common with the highest score images. On the contrary femoral neck and posterior condyles were not observed with the lowest score images, or the criteria were not clear and the reproducibility was insufficient. Conclusion: The anteversion CT has a larger scan range than Pelvis and hip CT, so there is much exposure. but there is more information provided than them. It is possible to provide reconstructed images for increasing pelvic and hip diseases. The soft ware MAR is expensive. so it is possible to provide bone metal modality preset images with high diagnostic value without software MAR.

A threshold value of 3.5 mm of passive anterior tibial subluxation on MRI is highly specific for complete ACL tears

To identify and quantify passive anterior tibial subluxation on MRI using a standardized measurement protocol and determine the diagnostic threshold of subluxation for complete anterior cruciate ligament tears. A retrospective case-control study was performed. Patients who underwent surgery for a complete isolated ACL tear between 2009 and 2015 were matched for age and gender to controls with an intact ligament on knee MRI. All subjects underwent 1.5T closed field MR imaging with the same protocol. Measurements were performed on axial sequences to evaluate translation of the medial and lateral condyles compared to the tibial plateau. Each compartment was measured between the vertical tangent to the posterior femoral condyles and the most posterior part of the tibial plateau. The main criterion was global passive subluxation measurements on MRI, corresponding to mean medial and lateral compartment subluxation. The reproducibility and diagnostic value of passive subluxation were calculated. Sixty (30/30) subjects were included, mean age 27.1 ± 1.7years, 20 women and 40 men. Patients had a significantly higher global passive subluxation than controls (3.3 ± 0.6mm vs 0.6 ± 0.2mm, respectively p < 0.00001). Reproducibility was excellent and the diagnostic value of passive subluxation for a complete ACL tear was fair. A passive subluxation threshold of 3.5mm had a sensitivity of 55.2%, a specificity of 100% and 77.6% of well-classified subjects. The calculated cutoff value for global passive subluxation to identify patients with a complete ACL tear was 3.5mm, with excellent specificity and a high positive likelihood ratio. Suboptimal clinical results following ACL reconstruction could be partially due to failure to restore an anatomical femorotibial relationship. III.

Two new species of the family Nippobodidae (Acari, Oribatida), including a description of the leg-folding process.

Nippobodespanemorfissp. n. and Leobodestrypasissp. n. are described by means of optical and Scanning Electron Microscopy (SEM) and compared to other congeners. The leg-folding process is described and illustrated.Nippobodespanemorfissp. n. is characterised by interlocking, double hook-shaped, posterior prodorsal condyle and anterior zone humeral apophysis; posterior prodorsal depression present. Tutorium a large lamina defining a pocket-shaped structure; bothridial opening ovoid, situated at the bottom of a U-shaped structure; deep, rounded-ovoid anterior notogastral depression present; ten pairs of notogastral setae; c setae looped, dentate, sharply tipped. Marginal setae h3, p3 on large promontories, followed by deep V-shaped incision; notogaster completely surrounded by circumgastric depression; lateral genital zone with locking structure constituted by longitudinal cuticular elevation, with promontories and a parallel furrow involved in the leg-folding process; genital plate smaller than anal plate.Leobodestrypasissp. n. is characterised by: the presence of posterior prodorsal depression and anterior notogastral depression; bridge-shaped anterior prodorsal condyles; heart-shaped frontal prodorsal orifice; ten pairs of notogastral setae; posterior prodorsal condyle and humeral condyle interlocked, forming double hook-like structure; circumgastric furrow surrounding entire notogaster; setae lp, h2, h1 situated on shallow medial furrow; notogastral setae lm, lp, h1, h2 medially aligned; p1, p2, p3, h3 marginally situated. Legs I-IV, tutorium, pedotectum I, and pedotectum II involved in leg folding which is inferred to be a protection mechanism.

Relationship Between Coronal Alignment and Rotational Profile of Lower Extremity in Patients With Knee Osteoarthritis

BackgroundWe aimed at determining whether the coronal alignment of lower extremity was related to rotational geometry of distal femur, femoral anteversion, and tibial torsion in patients with knee osteoarthritis. MethodsA total of 422 lower extremities were divided into 3 groups according to the coronal alignment: valgus (n = 31), neutral (n = 78), and varus group (n = 313). Condylar twisting angle was measured to determine rotational geometry of distal femur as the angle between the clinical transepicondylar axis and the posterior condylar line. Femoral anteversion was assessed using the angle between a line intersecting the femoral neck and the posterior condylar line (pFeAV) and the angle between the same line and transepicondylar axis that is not affected by posterior condylar variations (tFeAV). Tibial torsion was evaluated by measuring the angle between the posterior condyles of the proximal tibia and the transmalleolar axis. ResultsAs the coronal alignment changed from varus to valgus, the condylar twisting angle increased (r = 0.253, P < .001; 6.6° in varus, 7.4° in neutral, and 10.2° in valgus group). Although the pFeAV also increased (r = 0.145, P = .003), the tFeAV did not change significantly (P = .218). Mean tFeAV was 4.3° in varus, 4.7° in neutral, and 6.5° in valgus group. In contrast, as the coronal alignment changed from varus to valgus, the external tibial torsion increased (r = 0.374, P < .001; 22.6° in varus, 26.3° in neutral, and 32.6° in valgus group). ConclusionThe change patterns of the rotational profiles of the lower extremity according to the coronal alignment should be considered in order to obtain satisfactory rotational alignment after TKA.

Selection of Reference Axis for Distal Femoral Rotation in TKA: A Literature Review

Total knee arthroplasty (TKA) is widely accepted and standard surgical procedure for osteoarthritis. Most patients are able to recover their preoperative pain completely and achieve a good range of motions to perform daily tasks after TKA. However, there is a number of patients who remained unsatisfied with the result after TKA and often complain pain in performing daily task. Exploring reason behind post-operative pain and failure of TKA; researchers had found that in 31.2% of these cases; failure is due to aseptic loosening. Aseptic loosening is closely related to improper component placement. Orienting component in the axial direction is critical for proper outcome of TKA. Measured resection and gap balancing are two methods used for rotational alignment of component. Studies have shown that the measured resection technique has an advantage over gap balancing. However, the outcome of measured resection technique depends on the proper selection of reference axis. Transepicondyle axis, Whiteside line and Posterior condyle line are mostly used for setting the component rotation in TEA. All three rotational axis has its own advantages and pitfalls, therefore selection of reference should be based upon knee bone morphology and diseased condition. Malalignment of component placement in the axial plane may cause patella maltracking, anterior knee pain, aseptic loosening and also it could be one of the reasons behind TKA revision. The Success of rotational alignment depends upon proper preoperative planning and accurately selection of landmarks involved in creating axis. In this review paper, Pros and cons of reference axis are discussed individually and their correlations with each other are explored based on existing literature.

Short lateral posterior condyle is associated with trochlea dysplasia and patellar dislocation.

Surgeons mainly consider the anterior anatomy of the distal femur in the treatment of patellar instability (PI) with trochlear dysplasia (TD). Through this research, the idea was to analyse the posterior femoral condyle length in TD. The research team posited the presence of morphological differences in the posterior part of the femoral epiphysis in TD compared to a control group. They also postulated that the posterior bicondylar angle (PCA), in the axial plane, was increased in TD. This is a single-centre morphological study of 100 patients who had a computed tomography (CT) using the same protocol. 50 patients with PI (25 dysplasias A and 25 B-C-D according to the Dejour classification), and 50 controls were included. All patients presenting a clinical PI were considered for the study. None of these patients had undergone a surgical treatment prior to imaging. Demographic characteristics, BMI, and laterality were comparable in all patients. 20 pilot CT scans were used to establish the methodology. The following measurements were performed: anterior bicondylar angle, PCA, and condylar lengths with respect to the surgical transepicondylar axis. Ratios were calculated in relation to the femoral width. TD was classified according to the Dejour classification in grade A or grades B-C-D. An analysis of variance and a linear model were performed within some groups to investigate which parameters correlated with the classification's grade. This study showed a link between TD and the PCA: control group (1.4 ± 0.2°), type A group (1.6 ± 0.3°), and types B, C, D group (2.6 ± 0.3°) (p = 0.01). The difference between the control group and types B, C, D TD group was significant (p = 0.002). In groups B, C, D, the PCA was more important, which proves that in these groups the posterior part of the lateral condyle was relatively shorter compared to the medial condyle. The greater the dysplasia, the longer the medial condyle was in the anterior posterior (p = 0.02). This study shows not only an anterior but also a posterior anomaly in PI with TD. There is a correlation between the severity of the anterior deformation and the PCA: in other words, the knee is placed in valgus in flexure which promotes the external dislocation of the patella. This anatomical study could open a field of research on the development of surgical treatments based on the correction of posterior condylar femoral anomalies in PI. III.

Establishment of posterior tibial plateau partition and its clinical significance for surgical approach selection

Objective To explore the guiding significance of posterior tibial plateau partition for the selection of surgical approach in treatment for posterior column fracture. Methods From June 2008 to May 2015, 46 patients with posterior column fractures of tibial plateaus treated were retrospectively analyzed. There were 31 males and 15 females with an average age of 35.1±12.8 years old (range, 19-62 years). Nineteen patients were left side and twenty-seven patients were right side. Injury was caused by traffic accident in 27 cases, falling from bicycle in 12 cases and falling from height in 7 cases. On the basis of the posterior condyle with anatomical structure in tibial plateau, the posterior column was divided into four parts. All fractures were treated via the optimal approach based on the location of them. The posteromedial approach was used with fractures in zone 1 and 2, posterolateral approach used in zone 3, lateral approach via the fibular head osteotomy was used in zone 4 and combined approaches were used in multiple zones. All the fractures involved the posterior column were treated by anatomical reduction and fixation with plates and screws under direct vision. Results All the patients were followed up with an average of 15.5±3.7 months (range from 12 to 24 months). The healing time of all patients was 11-18 weeks, with an average time of 14.6±2.3 weeks. According to Rasmussen radiographic evaluation, the average score was 15.1 (range from 11 to 18) and clinical outcomes were rated with in 17 cases, in 24 cases, in 5 cases. The excellent and good rate was 89.1% (41/46). The mean HSS (the Hospital for Special Surgery) score of all patients at 12 months operatively were 86.7±8.6 (range from 67 to 98) and the functional scores were excellent in 25 cases, good in 17 cases and fair in 4 cases with the excellent and good rate was 91.3% (42/46). The average range of motion in affected knee was 118°±13.7° (range from 0° to 135°) in 17 cases via posterolateral approach, 123°±15.6° (range from 0° to 135°) in 18 cases via posteromedial approach, 115°±16.7° (range from 0° to 130°) in 18 cases via combined posteromedial and posterolateral approaches and 124°±7.4° (range from 0° to 130°) in 4 cases via the fibular head osteotomy lateral approach. Complications included fat liquefaction in 1 case, anterior tibial artery spasm in 1 case and traumatic arthritis in 1 case. Conclusion The partition of posterior tibial plateau can be used to guide the surgical approach to the posterior column simply and accurately. For the fractures of isolated posterior column and posterior column mainly involved, the partition has a certain guiding significance. Key words: Tibial fractures; Fracture fixation, internal; Treatment outcome

Feasibility of screw placement on posterior occipital condyle assisted by occipital tangent angulation

Objective: To investigate the practicability of occipital tangent angle in assisting posterior occipital condylar screw placement and to verify the safety and accuracy of self-made screw placement device for auxiliary screw. Methods: Occipito-cervical region specimens of 12 adult corpses were selected and scanned by thin-cut CT examination.The three-dimensional reconstruction of occipital and atlas was simulated for each specimen, and 3-matic software was used to measure the setting parameters, including occipital tangent angle, head obliquity, internal inclination angle, length of the screw and the distance from the inferior margin of hypoglossal canal to the screw axis.Using the self-designed occipital condylar screw placement device, combined with occipital tangent angle, internal inclination angle and insertion point, the posterior occipital condylar screw specimen was inserted with nails with assisting tool.The occipito-cervical region was reconstructed and scanned by thin-cut CT examination again after the operation to measuring the parameters of screw placement after actual screwing.The paired t test was used to compare the parameters of screw placement before and after operation. Results: Pre-operative three dimensional reconstruction of occipital condyle screw showed that the head obliquity was 5.3°±0.9°, the tangent angle was 14.9°±3.7°, the internal inclination angle was 28.1°±5.9°, and the length of screw insertion was (21.4±1.7) mm respectively; the distance from the inferior margin of hypoglossal canal to the screw axis was (4.74±0.36) mm.There was no significant difference in the parameters of analogue nailing between the left and right occipital condyles before the operation (t=-1.32, -0.48, 0.10, 0.23, 0.09, all P>0.05). The occipital condylar screw was safely implanted with screw placement device.The screw was located in the ideal nail insertion channel after operation by CT scan evaluation, without any injury to the hypoglossal canal, the atlanto-occipital articular surface and other structure.After the operation, the actual nailing parameters were measured: the head inclination angle was 5.2°±0.7°, the tangent angle was 15.1°±3.2°, the internal inclination angle was 28.2°±4.2°, the length of screw insertion was (21.5±1.7) mm, the distance from the inferior margin of hypoglossal canal to the screw axis was (4.54±0.29) mm.There was no significant difference between the left and right side in the actual screw placement parameters (t=-0.77, 0.82, 0.56, 0.22, 0.21, all P>0.05). It was found that there was no significant differences in the head obliquity, the occipital tangent angle, the internal inclination angle, length of screw entry, and the distance from the inferior margin of hypoglossal canal to the screw axis before and after the operation (t=0.56, -0.47, -0.18, -0.70, 1.89, all P>0.05). Conclusion: The occipital tangent angle can be measured directly in the process of posterior occipital condyle screw insertion to guide occipital condylar screw insertion, and the self-made occipital condylar screw placement device can effectively combine the three parameters: occipital tangent angle, head inclination angle and insertion point, which can improve the safety of posterior occipital condylar screw insertion.

Three-dimensional volumetric analysis of condylar head and glenoid cavity after mandibular advancement

The aim of this study was to assess condylar resorption, spatial change in glenoid cavity, and its risk factors after mandibular advancement by three-dimensional volumetric analysis. Subjects consisted of 30 condyles of 15 patients diagnosed with mandibular retrognathism who underwent Le Fort I and bilateral sagittal split ramus osteotomy advancement. CBCT images were taken before surgery (T0), immediately after surgery (T1), and postoperatively at 6 months (T2) and 1 year (T3). Condylar resorption was observed in 21 condyles. The posterior was the most affected region, while the anterior was the least affected. The volume of the glenoid cavity was significantly increased after surgery regardless of the presence or absence of resorption. However, the cavity recovered close to its original volume over time. At 1 year after surgery, the volume was not significantly different from the preoperative volume. Counterclockwise rotation of the proximal segment was found to be a risk factor affecting resorption based on correlation analysis. Mandibular advancement appeared to generate excessive mechanical stress on the posterior condyle, and might be responsible for the resorption. Counterclockwise rotation might have added stress to the region. Articular spatial change was transient and did not appear to be related to condyle resorption.

Development of a Novel Large Animal Model to Evaluate Human Dental Pulp Stem Cells for Articular Cartilage Treatment

PurposeChondral lesion is a pathology with high prevalence, reaching as much as 63% of general population and 36% among athletes. The ability of human Dental Pulp Stem Cells (DPSCs) to differentiate into chondroblasts in vitro suggests that this stem cell type may be useful for tissue bioengineering. However, we have yet to identify a study of large animal models in which DPSCs were used to repair articular cartilage. Therefore, this study aimed to describe a novel treatment for cartilage lesion with DPSCs on a large animal model.MethodsMesenchymal stem cells (MSC) were obtained from deciduous teeth and characterized by flow cytometry. DPSCs were cultured and added to a collagen type I/III biomaterial composite scaffold. Brazilian miniature pig (BR-1) was used. A 6-mm diameter, full-thickness chondral defect was created in each posterior medial condyle. The defects were covered with scaffold alone or scaffold + DPSCs on the contralateral side. Animals were euthanized 6 weeks post-surgery. Cartilage defects were analyzed macroscopically and histology according to modified O’Driscoll scoring system.ResultsFlow cytometry confirmed characterization of DPSCs as MSCs. Macroscopic and histological findings suggested that this time period was reasonable for evaluating cartilage repair. To our knowledge, this study provides the first description of an animal model using DPSCs to study the differentiation of hyaline articular cartilage in vivo.ConclusionThe animals tolerated the procedure well and did not show clinical or histological rejection of the DPSCs, reinforcing the feasibility of this descriptive miniature pig model for pre-clinical studies.

Posterior Reference Position Affects Intraoperative Kinematic and Soft Tissue Balance in Navigated Posterior-Stabilized Total Knee Arthroplasty

BackgroundThe importance of medial compartment stability is recognized in total knee arthroplasty (TKA). To manage the medial extension-flexion gap, the posterior reference position can be changed from conventional posterior center to posterior medial in measured resection techniques. This study aimed to compare the intraoperative soft tissue balance and rotational kinematics between the posterior medial and posterior center reference groups. MethodsWe enrolled 57 consecutive patients with varus osteoarthritis undergoing posterior-stabilized (PS) TKA using an image-free navigation system. The detailed surgical plan in both groups and intraoperative kinematics were recorded using navigation, and soft tissue balance measured with an offset-type tensor was statistically compared between groups. ResultsPatients were divided into the posterior center reference group (n = 32) and posterior medial reference group (n = 25). The posterior medial and posterior lateral condyles were significantly thicker in the posterior center reference group (P < .05). Although preoperative rotational kinematics were comparable between groups, the tibial rotational position was significantly more externally rotated in the posterior center reference group than in the posterior medial reference group at 45°, 60°, and 90° of flexion (P < .05). The varus angle and joint component gap were significantly smaller in the posterior medial reference group than in the posterior center reference group at 60° and 90° of flexion (P < .05). ConclusionThe posterior reference position affects intraoperative kinematics and soft tissue balance in navigated PS TKA. Posterior medial reference PS TKA decreases the excessive tibial external rotation during midflexion and increases the flexion stability compared with conventional posterior center reference PS TKA.

Cartilage can be thicker in advanced osteoarthritic knees: a tridimensional quantitative analysis of cartilage thickness at posterior aspect of femoral condyles

To test, through tridimensional analysis, whether (1) cartilage thickness at the posterior aspect of femoral condyles differs in knees with medial femorotibial osteoarthritis (OA) compared to non-OA knees; (2) the location of thethickest cartilage at theposterior aspect of femoral condyles differs between OA and non-OA knees. CT arthrograms of knees without radiographic OA (n = 30) and with severe medial femorotibial OA (n = 30) were selected retrospectively from patients over 50 years of age. The groups did not differ in gender, age and femoral size. CT arthrograms were segmented to measure the mean cartilage thickness, the maximal cartilage thickness and its location in a region of interest at the posterior aspect of condyles. For the medial condyle, mean and maximum cartilage thicknesses were statistically significantly higher in OA knees compared to non-OA knees [1.66 vs 1.46 mm (p = 0.03) and 2.56 vs 2.14 mm (p = 0.003), respectively]. The thickest cartilage was located in the half most medial aspect of the posterior medial condyle for both groups, without significant difference between groups. For the lateral condyle, no statistically significant difference between non-OA and OA knees was found (p ≥ 0.17). Cartilage at the posterior aspect of the medial condyle, but not the lateral condyle, is statistically significantly thicker in advanced medial femorotibial OA knees compared to non-OA knees. The thickest cartilage was located in the half most medial aspect of the posterior medial condyle. These results will serve as the basis for future research to determine the histobiological processes involved in this thicker cartilage. Advances in knowledge: This study, through a quantitative tridimensional approach, shows that cartilage at the posterior aspect of the medial condyles is thicker in severe femorotibial osteoarthritic knees compared to non-OA knees. In the posterior aspect of the medial condyle, the thickest cartilage is located in the vicinity of the center of the half most medial aspect of the posterior medial condyle. These results will serve as the basis for future research to determine the histobiological processes involved in this thicker cartilage.

Finite element analysis of occipital condylar screw in treatment of occipitocervical instability

Objective To explore the biomechanical properties of posterior occipital condyle screws compared with common occipitocervical fusion internal fixation and it's impacts upon stress of hypoglossal canals. Methods Finite element models based on the occipitocervical CT data of one 28-year-old male healthy volunteer were built, including normal model, instability model, internal fixation model by occipital condyle screws, internal fixation model by occipital plate screws, and internal fixation model by transarticular screws. Fifty N gravity and 1.5 N·m torque were exerted upon the surface of occipital bone so that the models could perform lateral bending, flexion, extension, and rotational motions. The motion range and stress distribution of internal fixation were compared under varying conditions among different occipitocervical fusion models. In addition, the impact of occipital condyle screw upon hypoglossal canals was examined. Results Compared with instability model, the motion range in the internal fixation model by occipital condyle screws declined by 96.8%, 95.6%, 95.0% and 98.5% respectively in lateral bending, flexion, extension and rotation. In the internal fixation by occipital plate screws, the motion range decreased by 96.3%, 95.7%, 98.4% and 99.6% respectively. In the internal fixation by transarticular screws, the motion range exhibited a decline of 95.7%, 94.0%, 94.3% and 98.9%, respectively. The stress peaks in the occipital condyle screw were 192.4 MPa, 201.6 MPa and 187.6 MPa under lateral bending, flexion, and rotation conditions, respectively. The stress peaks in the occipital plate screw were 279.6 MPa, 213.7 MPa, and 154.1 MPa, respectively. The stress peaks in the transarticular screw were 232.4 MPa, 220.9 MPa, and 224.5 MPa, respectively. The stress impact peak of occipital condyle screw on the hypoglossal canals wall was 12.96 MPa, and the content deformation under the hypoglossal canal was 0.64%. Conclusions The occipital condyle screw internal fixation has similar stability with common occipitocervical fusion fixations. The occipital condyle screw has more uniform stress distribution and less effect on the hypoglossal canals, and hence is safe and reliable as anchor point on the cranial side in occipitocervical fusion. Key words: Cervical vertebrae; Internal fixators; Finite element analysis; Spinal fusion

Regional Distribution of the Saphenous Nerve below the Adductor Canal: An Anatomical Study

The adductor canal is an aponeurotic tunnel that courses between the anterior and medial compartments in the middle third of the thigh. The canal begins at the apex of the femoral triangle and extends to the adductor hiatus. Its major contents are the superficial femoral artery, the nerve to vastus medialis, and the saphenous nerve. The latter two nerves are branches of the posterior division of the femoral nerve. Along with the medial and intermediate cutaneous nerves of the thigh and the lateral femoral cutaneous nerve the saphenous nerve contributes to the sensory distribution around the anterior aspect of the knee. This anatomic cadaveric study defined the course of the saphenous nerve and its divisions along the medial aspect of the knee. Landmark-based distance measurements were recorded in reference to the proximal border of the patella, medial border of the patella, medial epicondyle, medial femoral condyle, and posterior femoral condyle. The clinical implications of our findings suggest there is opportunity to obtain medial sensory analgesia during total knee arthroplasty when periarticular injections of bupivacaine derived medications are injected in the region of saphenous nerve proximal and posterior to the medial femoral condyle.

Posterior Condyle Offset and Maximum Knee Flexion Following a Cruciate Retaining Total Knee Arthroplasty.

Inconsistent data has been reported on the effect of the femoral posterior condyle offset (PCO) on the maximal knee flexion after total knee arthroplasty (TKA). This study investigated the relationship between the postoperative changes of the PCO and the changes of maximal knee flexion after a cruciate retaining (CR) TKA. Nine patients with medial osteoarthritis (OA) in one knee were investigated. Before operation, each index knee was magnetic resonance imaging (MRI) scanned for construction of a three-dimensional (3D) knee model. The patient then performed a maximal weight-bearing (WB) flexion and the index knee flexion was measured using a dual fluoroscopy technique. At an average of 8 months after a CR TKA, all patients performed the same WB knee flexion. The postoperative changes of the PCO, the posterior cruciate ligament (PCL) elongation, and the posterior tibial slope (PTS) were determined. The postoperative changes of maximal knee flexion were determined by comparing with the preoperative maximal flexion angles of the knee. The correlations of the postoperative changes of PCO and PTS with the postoperative changes of the maximal flexion angle and PCL elongation of the knee were analyzed. The preoperative PCO (28.5 ± 4.5 mm) was significantly smaller than the postoperative PCO (31.1 ± 5.1 mm) (p < 0.05). The increasing of PCO after surgery is correlated with the decreasing of maximal knee flexion angle (r = 0.74) and the increasing of PCL elongation (r = 0.64) after the TKA. The PTS was not found to change significantly after the TKA and was not significantly correlated to the maximal knee flexion angle and PCL elongation. The postoperative increases of the PCO were shown to cause overstretching of the PCL and poor flexion angle of the knee after the CR TKA. Restoration of PCO could help optimize the maximal flexion of the knee after the TKA with consideration about PCL tension.

Femoral rotational asymmetry is a common anatomical variant.

The sulcus line (SL) is a three-dimensional landmark that corrects for individual variation in the coronal alignment of the trochlear groove in contrast to the traditional Whiteside's line (WL). Femoral rotational asymmetry (FRA) is an anatomical variation in which the posterior condyles and trochlear groove are not perpendicular to each other. This study aims to measure the SL and assess its reliability relative to WL, in addition to measuring and classifying the FRA. A retrospective analysis of a series of 191 CT scans of nonarthritic knees was performed. Measurements were taken of rotational landmarks in three-dimensional reconstructions. The variability and outlier rate of SL was less than WL (P < 0.05), however, it was also greater than the posterior condylar line (PC) (P < 0.05). Averaging the PC + 3° and the SL did not change the rate of femoral malrotation relative to the surgical epicondylar axis (SEA) (P > 0.05), however it decreased the rate of change of the rotational alignment of the trochlear groove between the native knee and the prosthetic knee from 31% to 5% (P < 0.05). FRA was classified and was >5° in 56/191 (29%) of cases. The SL technique is more accurate than WL for determining the rotational alignment of the trochlear groove. Nonarthritic femora have a high rate of rotational asymmetry. Identifying and classifying FRA in individual cases allows the femoral component to be inserted in a position which gives the best possible match to both the native posterior condyles and trochlear groove. Clin. Anat. 31:551-559, 2018. © 2018 Wiley Periodicals, Inc.

Pearls: Early Removal of Posterior Osteophytes in TKA.

Posterior-compartment osteophytes are commonly encountered during TKA. They can limit or prevent terminal extension by tenting the posterior capsule and can cause coronal plane imbalance due to tenting of adjacent capsulo-ligamentous structures. Osteophyte removal is a principle of TKA soft-tissue balancing [2]. Failure to remove an osteophyte may result in unnecessary soft-tissue releases or lead to additional bone resection. Posterior femoral osteophytes can be difficult to remove because they are hard to see, and surgeons may be concerned about passing a sharp instrument posteriorly, near the popliteal neurovascular structures. Surgeons generally remove them after resection of the distal, anterior, and posterior femur and proximal tibia. After these resections, the surgeon should have easier access to the posterior compartment. However, this technique requires the surgeon to determine the femoral component rotation before osteophyte removal. In our experience, determining the femoral component rotation before large (> 1 cm) posterior osteophytes are removed can result in coronal plane imbalance of both the flexion and extension gaps because of the remaining tenting effect of the retained posterior osteophytes. Therefore, we suggest that surgeons remove these osteophytes before the anterior and posterior femoral cuts are completed. Here, we describe our technique, which allows access to the posterior compartment before the final femoral component rotation is determined [1]. This early posterior osteophyte removal technique is applicable to measured resection, kinematic alignment, as well as our preferred gap balancing technique. Many patients with large posterior osteophytes also have advanced medial-compartment arthritis and a fixed-varus deformity (Fig. 1A-B). After knee exposure, the deep medial collateral ligament is released to the mid-coronal plane of the tibia. Additional soft-tissue releases should then be delayed until all femoral and tibial osteophytes are removed. We favor resection of the extension space (distal femur and proximal tibia) followed by removal of medial and lateral distal femoral and peripheral tibial osteophytes that might tent surrounding ligamentous structures.Fig. 1 A-B: (A) AP radiograph of right knee with fixed varus deformity and advanced arthritis is shown. (B) Lateral radiograph of right knee with large posterior femoral osteophyte, denoted by arrow is shown. (Published with permission from Douglas A. Dennis MD).A spacer block is inserted into the extension gap. Residual medial soft tissue tightness is typically encountered, and so at this point we remove any large posterior femoral osteophytes. The femoral component sizing guide then is applied to determine femoral component size. With the knee flexed 90°, a laminar spreader is inserted into the lateral flexion gap and tensioned. A retractor is placed medially to protect the medial collateral ligament (Fig. 2). A 4-mm resection of the posterior aspect of the medial femoral condyle is performed with an oscillating saw, providing access to the posterior compartment (Fig. 3). The interface between osteophyte and native femur is then visualized (Fig 4). A curved osteotome is used to divide the osteophyte at that interface (Fig 5). During this maneuver, it is common to observe some degree of opening of the flexion gap since the tenting effect of the posterior femoral osteophyte on the posterior capsule and posterior oblique ligament has been eliminated. The posterior femoral osteophyte is then removed with a rongeur (Fig. 6). While this technique has been most commonly used to remove large posteromedial femoral osteophytes in knees with varus deformity, the technique is applicable and has been utilized in knees with valgus deformity and large posterolateral femoral osteophytes as well.Fig. 2: Intraoperative photo shows a planned posterior preliminary resection, marked in ink on the femur, and denoted by the arrow. A retractor is protecting the medial collateral ligament. (Published with permission from Douglas A. Dennis MD).Fig. 3: An oscillating saw used to perform preliminary resection provides access to the posterior compartment of the knee. (Published with permission from Douglas A. Dennis MD).Fig. 4: A demonstration of the interface of normal condyle of the femur and the posterior osteophyte is shown, indicated by the arrow. (Published with permission from Douglas A. Dennis MD).Fig. 5: A curved osteotome divides the posterior osteophyte from the normal bone of the posterior condyle. (Published with permission from Douglas A. Dennis MD).Fig. 6: A pituitary rongeur extracts the resected posterior osteophyte. (Published with permission from Douglas A. Dennis MD).Extension gap tension and balance then are assessed. If imbalance persists, additional medial soft-tissue releases are performed until the gap is balanced. The AP femoral cutting block is then applied using the surgeon’s preferred method to obtain a rectangular flexion gap (measured resection guide or flexion gap tensioning). The remaining steps of the TKA are then completed in routine fashion. Large posterior femoral osteophytes contribute to soft-tissue imbalance, and we believe benefit from early removal before extensive soft tissue releasing is performed and femoral component rotation is determined.