Reliability of Tibial Tubercle-Trochlear Groove Distance for Assessing Tibial Tubercle Lateralization: A Study Comparing Different Anatomic References.

Background: The tibial tubercle-trochlear groove (TT-TG) distance is a measurement used to quantitatively assess tibial tubercle lateralization (TTL), and it has important reference value for the treatment of patellar dislocation (PD). However, TT-TG distance accuracy has been questioned, so many new parameters have been proposed. Purpose: To compare which of the TT-TG, tibial tubercle-midepicondyle (TT-ME), tibial tubercle-Roman arch (TT-RA), tibial tubercle-tibial intercondylar midpoint (TT-TIM), and tibial tubercle-mid inter-epicondyle trochlea intersection (TT-MIELTI) distances better reflect TTL in patients with PD. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: A total of 96 patients who had undergone surgery for PD and 96 patients without PD (controls) were included in the study. The patients had all undergone computed tomography examination. The TT-TG, TT-ME, TT-RA, TT-TIM, TT-MIELTI distances and the TTL distance were measured independently by 2 surgeons in a blinded and randomized fashion. The t test was used to detect whether the parameters were significantly different between the 2 groups. The TTL distance was used as a reference value for lateralization of tibial tubercle. Pearson correlation coefficients were calculated to determine correlations between the defined measurements. Results: The intra- and interobserver reliability of the defined measurements was excellent. All parameters except for TT-TIM distance were significantly larger in the PD group than the control group (P < .01 for all). There was a moderate correlation (r = 0.601) between the TT-TG distance and TTL, and other parameters were less correlated with TTL. Conclusion: Among 5 the parameters tested, the TT-TG distance still had the highest correlation with TTL and was able to reflect TTL better in patients with PD. The role of TT-TIM distance in the assessment of PD needs further study.

Arthroscopic Linear Chain Fixation for the Treatment of Medial Meniscus Posterior Root Tear: A Case Study.

BACKGROUND: The repair and reconstruction of medial meniscus posterior root tears (MMPRTs) is an important issue in the field of orthopedic sports medicine. This study reports the first application of arthroscopic linear chain fixation for the treatment of MMPRTs. CASE PRESENTATION: A 78-year-old female patient presented with a 1.5-month history of right knee pain accompanied by a locked facet joint. The patient underwent surgery with the new linear chain fixation method. In this method, the suture and the loop part of the buckle-strap titanium plate were combined into a linear chain mechanical complex, and the tension of the posterior root stump was gradually increased by pulling on the two attachment lines at the external mouth of the tibial tunnel. The postoperative Lysholm score was 89, and the visual analogue scale score was 0.9, indicating a significant improvement in knee joint function. At the 7-month and 1-year post-surgery follow-up, physical and MRI examinations confirmed satisfactory healing of the MMPRTs. CONCLUSION: This surgical approach offers several benefits, including a simplified instrumentation setup, preservation of natural anatomical structures, and reliable residual stump fixation. It has the potential for clinical implementation.

The influence of varus and valgus deviation on the contact area of patellofemoral joint in healthy knees.

OBJECT: Varus-valgus lower alignment is a risk factor for patellofemoral osteoarthritis, but malalignment alone affect not only the tibiofemoral joint but also the patellofemoral joint. The aim of the present study was to analyse the contact area of patellofemoral joint in varus alignment and valgus alignment of healthy subjects using magnetic resonance imaging. METHODS: Twenty-six healthy subjects with valgus lower limb alignment (Group I, n = 26) and twenty-six volunteers with varus lower limb alignment (Group II, n = 26) was performed. An MRI scan was used to capture and measure the patellofemoral joint articular cartilage contact area at different degrees of knee flexion (20°, 40°,60°) in passive movement. All subjects were categorized on the basis of the global limb alignment and mechanical alignment of the femur and tibia. Varus alignment is hip-knee-ankle angle ≥ 3°; and valgus alignment is hip-knee-ankle angle ≥ - 3°. To obtain medial facet contact area and lateral facet contact area for each slice, the length of each respective line of contact was multiplied by the 5 mm slice thickness. RESULTS: The overall joint contact area increased from 168.0 ± 20.5 mm2 at 20° knee flexion to 334.4 ± 30.5 mm2 at 60° knee flexion in group (I) The overall joint contact area increased from 178.0 ± 18.9 mm2 at 20° knee flexion to 328.9 ± 27.2 mm2 at 60° knee flexion in group (II) There was a significant difference in lateral facet contact area between group I and group II at 40° of knee flexion. There was significantly different in medial facet contact area between group I and group II at 20° and 40° of knee flexion. CONCLUSIONS: Throughout the knee movement, the contact area on the lateral facet of the patellofemoral joint was greater in the valgus group. In the early phase of knee flexion, the contact area of the medial patellofemoral joint was larger in the varus group. Lower alignment is an important factor in patellofemoral joint degeneration.

Contact area and pressure changes of patellofemoral joint during stair ascent and stair descent.

PURPOSE: To investigate the differences of patellofemoral joint pressure and contact area between the process of stair ascent and stair descent. METHODS: The finite element models of 9 volunteers without disorders of knee (9 males) to estimate patellar cartilage pressure during the stair ascent and the stair descent. Simulations took into account cartilage morphology from magnetic resonance imaging, joint posture from weight-bearing magnetic resonance imaging, and ligament model. The three-dimension models of the patella, femur and tibia were developed with the medical image processing software, Mimics 11.1. The ligament was established by truss element of the non-linear FE solver. The equivalent gravity direction (-z direction) load was applied to the whole end of femur (femoral head) according to the body weight of the volunteers, and the force of patella was observed. A paired-samples t-test or Wilcoxon rank sum test to make comparisons between stair ascent and stair descent. Statistical analyses were performed using SPSS 22.0 using a P value of 0.05 to indicate significance. RESULTS: During the stair descent (knee flexion at 30°), the contact pressure of the patella was 2.59 ± 0.06Mpa. The contact pressure of femoral trochlea cartilage was 2.57 ± 0.06Mpa. During the stair ascent (knee flexion at 60°), the contact pressure with patellar cartilage was 2.82 ± 0.08Mpa. The contact pressure of the femoral trochlea cartilage was 3.03 ± 0.11Mpa. The contact area between patellar cartilage and femoral trochlea cartilage was 249.27 ± 1.35mm2 during the stair descent, which was less than 434.32 ± 1.70mm2 during the stair ascent. The area of high pressure was located in the lateral area of patella during stair descent and the area of high pressure was scattered during stair ascent. CONCLUSION: There are small change in the cartilage contact pressure between stair ascent and stair descent, indicating that the joint adjusts the contact pressure by increasing the contact area.

Platelet-Derived Exosomes Alleviate Knee Osteoarthritis by Attenuating Cartilage Degeneration and Subchondral Bone Loss.

BACKGROUND: Osteoarthritis (OA) is the most prevalent chronic degenerative joint disease among the aged population. However, current treatments for OA are limited to alleviating symptoms, with no therapies that prevent and regenerate cartilage deterioration. PURPOSE: To assess the effects of platelet-derived exosomes (Plt-exos) on OA and then to explore the potential molecular mechanism. STUDY DESIGN: Controlled laboratory study. METHODS: Exosomes derived from human apheresis platelets were isolated and identified. The effects of Plt-exos in protecting chondrocytes under interleukin 1ß stimulation were evaluated by analyzing the proliferation and migration in human primary chondrocytes. RNA sequencing was later performed in vitro for primary chondrocytes to reveal the underlying mechanisms of Plt-exo treatment. Anterior cruciate ligament transection was used to construct an OA mice model, and intra-articular injection of Plt-exos was given once a week for 6 weeks. Mice were sacrificed 4 weeks after the last injection. Histologic and immunohistochemistry staining and micro-computed tomography analysis were performed to assess alterations of articular cartilage and subchondral bone. RESULTS: Plt-exos significantly promoted proliferation and migration of chondrocytes within a dose-dependent manner, as well as dramatically promoted cartilage regeneration and attenuated abnormal tibial subchondral bone remodeling, thus slowing the progression of OA. After being treated with Plt-exos, 1797 genes were differentially expressed in chondrocytes (923 upregulated and 874 downregulated genes). Functional enrichment results and hub genes were mainly involved in anti-inflammatory effects, mediating cell adhesion, stimulating cartilage repair, promoting anabolism, and inhibiting catabolism. CONCLUSION: Our results demonstrated that Plt-exos promoted chondrocyte proliferation and migration in vitro, as well as attenuated cartilage degeneration, improved the microarchitecture of subchondral bone, and retarded OA progression in vivo. CLINICAL RELEVANCE: Our study illustrated that the administered Plt-exos could alleviate knee OA by attenuating cartilage degeneration and subchondral bone loss, possibly serving as a novel promising treatment for OA in the future.

Isolated medial patellofemoral ligament reconstruction is valid to stabilize patellofemoral joint but uncertain to reduce patellar height in setting of lateral patellar dislocation and patella alta.

INTRODUCTION: Medial patellofemoral ligament reconstruction (MPFLR) is the most commonly used surgical treatment for patients with lateral patellar dislocation (LPD). It is still poorly understood whether or not MPFLR has a contributory effect on decreasing patellar height. MATERIALS AND METHODS: Forty-five patients who underwent isolated MPFLR for LPD and patella alta were evaluated with a mean follow-up period of 24 months (22-25 months). Knee joint functions were evaluated by Banff patellofemoral instability instrument (BPII) 2.0 scores and Kujala scores. Patellofemoral engagement and stability were assessed by the patella tilt angle (PTA) and patellar congruence angle (PCA) measured by CT scans, and the patellar-glide test. Patellar height was calculated on lateral radiographs according to three methods: Caton-Deschamps ratios (CDR), Insall-Salvati ratios (ISR), and Blackburne-Peel ratios (BPR). A threshold value of p < 0.05 denoted a statistically significant difference. RESULTS: Significant improvements were found in both BPII 2.0 scores, which increased from 41.7 to 77.8 (p < 0.001) and Kujala scores, which increased from 49.2 to 85.5 (p < 0.001). Post-operative PTAs and PCA decreased from 19.6 ± 8.8 to - 3.4 ± 6.2, and from 24.6 ± 7.3 to 13.1 ± 3.8 degrees respectively (p < 0.001). No patients showed lateral translation more than grade II in the patellar-glide test. Regarding patellar height, a tiny reduction (Δ = 0.02, Δ max = 0.09) was discovered in using CDR (p = 0.027), rather than ISR or BPR. All measurements of radiographic indices had an excellent intra- and inter-rater reliability (ICC > 0.75). CONCLUSIONS: Isolated anatomic MPFLR is sufficient to achieve good clinical outcomes, as well as patellofemoral stability and high rates of return-to-sport. However, it is unclear if the reconstructed MPFL has a contributory effect on reducing patellar height.

RNA-seq based integrative analysis of potential crucial genes and pathways associated with patellar instability.

Patellar instability (PI) is a common knee injury in adolescents, but the crucial biomarkers and molecular mechanisms associated with it remain unclear. We established a PI mouse model and investigated PI-related changes in gene expression by RNA sequencing (RNA-seq). Differentially expressed gene (DEG) analysis and enrichment analysis were performed to identify crucial genes and pathways associated with PI. Subsequently, a protein-protein interaction, DEG-miRNA, DEG-transcription factors, and DEG-drug interaction networks were constructed to reveal hub genes, molecular mechanism, and potential drugs for PI. Finally, the reliability of the sequencing results was confirmed by real-time quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry. Upon comparison with the control group, 69 genes were differently expressed in PI, including 17 upregulated and 52 downregulated ones. The DEGs were significantly enriched in Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway and immune responses. The protein-protein interaction network identified ten PI-related hub genes, all of which are involved in the JAK/STAT signaling pathway or inflammation-related pathways. DEG-miRNA and DEG-transcription factor networks offered new insights for regulating DEGs post-transcriptionally. We also determined potential therapeutic drugs or molecular compounds that could restore dysregulated expression of DEGs via the DGIdb database. RT-qPCR results were consistent with the RNA-seq, confirming the reliability of the sequencing data. Immunohistochemistry results suggested that JAK1 and STAT3 expression was increased in PI. Our study explored the potential molecular mechanisms in PI, provided promising biomarkers and suggested a molecular basis for therapeutic targets for this condition.

Can Traditional Straight-leg Swaddling Influence Developmental Dysplasia of the Femoral Trochlea? An In Vivo Study in Rats.

BACKGROUND: It has been reported that trochlear dysplasia occurs very early in development, and environmental factors like swaddling may cause developmental dysplasia of the hip, which is associated with a shallower trochlear groove. However, to our knowledge, there are no definitive studies about the relationship between trochlear dysplasia and traditional straight-leg swaddling. QUESTIONS/PURPOSES: Using a rat model of femoral trochlear dysplasia, we asked: Does straight-leg swaddling for 1 and 2 weeks in newborn Wistar rats alter the femoral trochlea with respect to (1) gross morphology, (2) histologic appearance, as well as (3) trochlear sulcus angle, width, and depth? METHODS: Eighty-four newborn Wistar rats (44 females and 40 males) were divided into two equal groups: 42 in the unswaddled group and 42 in the swaddled group; each group was comprised of 22 females and 20 males. In the swaddled group, the rats were wrapped in surgical tape to maintain hip and knee extension to simulate traditional human straight-leg swaddling. To determine whether longer periods of swaddling were associated with more severe trochlear dysplasia, 21 rats in each group were euthanized at 1 and 2 weeks, respectively, and the gross morphology of the femoral trochlea was observed by one observer blinded to condition. Then hematoxylin and eosin staining of the femoral trochlea was performed and the distribution and number of the chondrocytes of the trochlear groove were viewed through a microscope. The trochlear sulcus angles, depth, and width were measured by an experienced technician blinded to condition. RESULTS: By observing the gross morphology, we found that the trochlear groove in the swaddled group became qualitatively flatter compared with the unswaddled group at 1 week, and at 2 weeks, the trochlear groove became much shallower. At 1 and 2 weeks, histologic examinations showed obvious qualitative changes in the distribution and number of chondrocytes of the trochlear groove in the swaddled than in the unswaddled groups. In the swaddled group, trochlear dysplasia was more common at 2 weeks, occurring in 62% (26 of 42 [16 of 22 females and 10 of 22 males]) versus 33% (14 of 42 [8 of 22 females and 6 of 20 males]) at 1 week. At 1 week, the swaddled group showed more trochlear dysplasia compared with the unswaddled group as measured by angle of the trochlear groove (137° ± 6° versus 132°± 3.6°, mean difference 5° [95% confidence interval 2.9° to 7.2°]; p < 0.001), depth of the trochlear grove (0.28 ± 0.04 mm versus 0.31 ± 0.02 mm, mean difference 0.03 mm [95% CI 0.01 to 0.04]; p < 0.001). At 2 weeks, the swaddled group showed more severe trochlear dysplasia than at 1 week compared with the unswaddled group as measured by the angle of the trochlear groove (135° ± 6.0° versus 128° ± 4.8°, mean difference 7° [95% CI 5.7° to 10.4°]; p < 0.001), depth of the trochlear grove (0.32 ± 0.04 mm versus 0.36 ± 0.02 mm, mean difference 0.04 mm [95% CI 0.03 to 0.06]; p < 0.001). There was no difference in the width of the trochlear sulcus between the swaddled and the unswaddled groups at 1 week (1.29 ± 0.14 mm versus 1.30 ± 0.12 mm, mean difference 0.01 mm [95% CI -0.05 to 0.07]; p = 0.73) and 2 weeks (1.55 ± 0.12 mm versus 1.56 ± 0.12 mm, mean difference 0.01 mm [95% CI -0.05 to 0.07]; p = 0.70). CONCLUSION: Our results indicate that traditional straight-leg swaddling could induce trochlear dysplasia in this model of newborn rats. With an increased swaddling time of 2 weeks, more severe trochlear dysplasia appeared in the swaddled group. CLINICAL RELEVANCE: Our findings suggest that traditional straight-leg swaddling may impair trochlear development in the human neonate and lead to trochlear dysplasia in infants. We believe our animal model will be useful in future work to observe and study the change of cartilage and subchondral bone in each stage of the development of trochlear dysplasia and the change of mechanotransduction-associated proteins (such as, TRPV4/ Piezo1 and CollagenⅡ) in cartilage and subchondral osteocytes. It will also be helpful to further investigate the mechanism of developmental femoral trochlea dysplasia caused by biomechanical changes.

The tibial tubercle-posterior cruciate ligament (TT-PCL) distance does not truly reflect the lateralization of the tibial tubercle.

PURPOSE: The role of the tibial tubercle-posterior cruciate ligament (TT-PCL) and tibial tubercle-trochlear groove (TT-TG) in recurrent patellar instability (RPI) remains unclear. This study aims to confirm the validity of the TT-TG and TT-PCL in predicting RPI and to verify whether the TT-PCL can truly reflect the lateralization of the tibial tubercle. METHODS: A total of 50 patients with RPI and 50 controls were recruited and underwent magnetic resonance imaging examinations. The TT-TG, TT-PCL, and tibial tubercle lateralization (TTL) were measured independently by two authors in a blinded and randomized fashion. T-test was used for parametric variances and the Mann-Whitney U and Chi-square tests were used for non-parametric variances. Pearson's product moment correlation coefficients were calculated to determine correlations between the defined measurements. The intraclass correlation coefficient was used to assess the reliability of the measurements. RESULTS: All defined measurements showed excellent intra- and inter-observer reliability. The TT-TG distance, TT-PCL distance, and TTL were significantly greater in the PI group than in the control group. The AUC was highest for the TT-TG distance compared with that for the TT-PCL distance, and TTL were 0.798, 0.764, and 0.769, with the calculated cut-off value of 12.5 mm, 16.5 mm, and 66.1 percentages. There was a moderate correlation (r = 0.595) between the TT-TG distance and TTL, and a weak correlation (r = 0.430) between the TT-PCL distance and TTL. CONCLUSION: Both the TT-TG distance and TT-PCL distance can be measured with excellent reliability on magnetic resonance imaging. The TT-TG distance, rather than the TT-PCL distance, has a better performance in predicting RPI. Most interestingly, the TT-PCL distance cannot reflect the real lateralization of TT. This study provides new information to evaluate TTL in patients with RPI. LEVEL OF EVIDENCE: III.

What is the relationship between the breech presentation and femoral trochlear dysplasia? An experimental study of the breech presentation model in neonatal rats.

BACKGROUND: The relationship between breech presentation and trochlear dysplasia has been confirmed. However, the pathological process of breech-related trochlear dysplasia remains unclear. This study aimed to establish an animal model to simulate breech presentation and to analyze the pathological process of the femoral trochlea. MATERIALS AND METHODS: One hundred and twenty neonatal rats were randomly assigned into a control group and two experimental groups that were swaddled (using surgical tape) to keep the hip flexed and knees extended to simulate human breech presentation for the 5 days (short Swaddling) and the 10 days (prolonged Swaddling) of life. Gross and cross-sectional observation, histological staining measurement in two experimental time points (5 and 10 days after birth) were conducted to evaluate the morphological changes of the femoral trochlea. RESULTS: The incidence of trochlear dysplasia increased with the Swaddling time. Rats in the prolonged Swaddling group had the high prevalence of trochlea dysplasia (52 of 60), followed by short Swaddling group (42 of 60). Gross and cross-sectional observation showed a shallower trochlea groove in two experimental groups. Histologicalstaining measurement indicated that the trochlear sulcus angle and trochlear sulcus depth were significantly different between the experimental group and the control group since day 5 and day 10. CONCLUSION: In this model, breech presentation had an adverse effect on neonatal knees and could induce trochlear dysplasia. In addition, this study also showed that the more time in breech presentation, the more incidence of trochlear dysplasia.

The effect of increased femoral anteversion on the morphological and trabecular microarchitectural changes in the trochlea in an immature rabbit.

Increased femoral anteversion (FA) has been recently demonstrated as one risk factor for recurrent patellar dislocation (RPD). However, it has been still unclear whether the increase of FA can result in patellar dislocation, and subsequent morphological and trabecular microarchitectural changes in the trochlea has not been investigated. Forty knees from 20 rabbits at 3 months of age were included. The right knees underwent surgery with internal rotation of distal femur to increase FA, with the left knees acting as internal controls. The surgical knees were called operated group, and non-operated knees were control group. Micro-CT scans for distal femur were acquired after 4 months of surgery. In the operated group, a boss located proximal to the entrance of the groove was formed. The central trochlear height was significantly greater, sulcus angle was significantly greater, both lateral and medial trochlear slope were significantly lower, and boss height was significantly greater in comparison to the control group. Regarding the microarchitectural changes, the trabecular thickness were increased by 67.5% at the groove, 33.0% and 29.5%, at the medial and lateral femoral condyle, and trabecular number were decreased by 37.8% and 26.5% at the groove and medial femoral condyle. This study provided a novel animal model of trochlea dysplasia by femoral rotational osteotomy and increased FA. These changes were associated with the load redistribution in the patellofemoral joint after the increase of FA.

Hemostatic techniques to reduce blood transfusion after primary TKA: a meta-analysis and systematic review.

PURPOSE: To investigate the efficacy of non-tranexamic acid (TXA) on reducing blood loss and requirements of allogeneic blood transfusion (ABT) in total knee arthroplasty (TKA). METHODS: The PubMed, EMBASE, and the Cochrane Library databases were researched since incipiency to June 2018. Only randomized controlled trials (RCTs) involved with non-TXA hemostatic techniques in TKA met the inclusion criteria. RESULTS: A total of 36 RCTs, including 1511 patients, were recruited for analysis. The results of subgroup analysis revealed that hemostatic techniques, which could substantially decrease the rate of ABT, were cell salvage with the transfusion trigger of 9 mg/dl, fibrin sealant with a dosage of 10 ml, and postoperative flexion position. CONCLUSION: The available evidence in this meta-analysis suggests that postoperative flexion position, fibrin sealant, and cell salvage can substantially decrease the rate of ABT in TKA. Further studies, including more hemostatic methods and high-quality research, are expected.

Long term results after double and single bundle ACL reconstruction: Is there any difference? A meta - analysis of randomized controlled trials.

OBJECTIVE: The double-bundle (DB) techniques are considered to yield better stability of the knee compared with single-bundle (SB) for anterior cruciate ligament (ACL) reconstruction. However, most studies followed up patients in short to middle-term within 5 years, and the longer-term efficacy of SB and DB ACL reconstruction is still beyond consensus. The purpose of this meta-analysis is to compare the longer-term efficacy between double-bundle (DB) and single-bundle (SB) techniques. METHODS: PubMed, EMBASE, and Cochrane Library databases were searched for relevant articles published up to November, 2017 with an English language restriction. The searches were limited to human subjects and randomized controlled trials (RCTs). In addition, the reference lists of identified articles were checked manually to avoid missing other potentially eligible studies. This process was performed iteratively until no additional articles could be included. The quality of the included studies was assessed using The Cochrane Collaboration's risk of bias tool. All statistical analyses were performed with Review Manager soft-ware. RESULTS: A total of five RCTs involving 294 patients were included finally. No studies were excluded due to insufficient data or low quality. The pooled results showed no statistically significant difference between SB and double bundle DB reconstructions for Lysholm, IKDC, pivot shift, KT scores, and the development of osteoarthritis at a minimum of 5 years. No significant heterogeneity was found across all outcomes. CONCLUSION: The best available evidence demonstrated that SB and DB techniques could yield similar efficacy for ACL reconstruction. And no superiority was founded in DB ACL reconstruction with a minimal 5-year follow-up. Given that, the relatively simple and proven techniques of SB ACL reconstruction may be preferable for orthopedic surgeons. LEVEL OF EVIDENCE: Level I, Therapeutic Study.

Evaluation of Trochlear Dysplasia Severity Using Trochlear Angle: A Retrospective Study Based on Computed Tomography (CT) Scans.

BACKGROUND Trochlear dysplasia is an important pathological factor in patellofemoral instability. Quantitative evaluation of the severity of trochlear dysplasia is rare and remains unclear. MATERIAL AND METHODS Computed tomography (CT) data on 136 knees (95 patients) with trochlear dysplasia in the case group and an age- and sex-matched cohort of 120 knees (70 patients) in the control group were collected for this retrospective study. All participants had undergone CT scans in the supine position. The trochlear angles (TA) formed by the posterior condylar line and the trochlear line were calculated and compared. The threshold for statistical significance was set at p<0.05. RESULTS The mean TA values were significantly greater in the case group compared to the control group independent of sex (p<0.01). The distribution of trochlear dysplasia of Dejour grades was type A n=34, type B n=31, type C n=40, and type D n=31. Except for types A and B, differences in the trochlear dysplasia grade between any 2 other types were statistically significant (p<0.01). CONCLUSIONS The technique of measuring TA is reproducible and accurate in patients with patellar instability and normal controls. The TA positively correlates with higher levels of trochlear dysplasia. This technique can help to evaluate and treat trochlear dysplasia in research as well as in clinical practice.

Double-bundle anatomical medial patellofemoral ligament reconstruction with lateral retinaculum plasty can lead to good outcomes in patients with patellar dislocation.

PURPOSE: To evaluate the clinical outcomes of double-bundle anatomical medial patellofemoral ligament (MPFL) reconstruction combined with lateral retinaculum plasty versus isolated MPFL reconstruction for patellar dislocation. METHODS: From 2011 to 2013, 64 patients underwent either double-bundle anatomical MPFL reconstruction combined with lateral retinaculum plasty (Group A, 32 patients), or isolated MPFL reconstruction (Group B, 32 patients). Clinical evaluations were performed 2 years post-operatively and included determination of the number of patients with patellar redislocation, the patellar tilt angle, lateral patellar shift, subjective symptoms, and functional outcomes as evaluated with the Kujala score and Lysholm score. RESULTS: No dislocation or subluxation occurred during the 25-month follow-up. Radiographically, the patellar tilt angle was 6.0° ± 1.7° in Group A and 6.7° ± 2.0° in Group B, without a significant difference (n. s). The lateral patellar shift was 8.0 ± 2.6 mm in Group A and 8.5 ± 2.4 mm in Group B (n. s). The mean Kujala score was 91.8 ± 3.7 in Group A and 91.5 ± 3.6 in Group B post-operatively (n. s), and the mean Lysholm score was 92.5 ± 3.8 and 90.8 ± 4.9, respectively (n. s). CONCLUSIONS: Double-bundle anatomical MPFL reconstruction with lateral retinaculum plasty is a promising procedure that provides a new option for patellar dislocation. LEVEL OF EVIDENCE: III.

Clinical outcomes of medial collateral ligament injury in total knee arthroplasty.

Intraoperative injury to the medial collateral ligament (MCL) during total knee arthroplasty (TKA) is a rare but severe complication. The main treatment methods are primary repair and revision with a more constrained implant; however, the clinical outcomes of primary reconstruction without a constrained implant have rarely been reported.A retrospective study was performed to evaluate the prevalence of iatrogenic injury to the MCL during primary TKA, and to report the clinical outcomes of MCL reconstruction without the use of a constrained device.A total of 1749 patients (2054 knees) underwent primary TKA between 2007 and 2013 and were retrospectively evaluated. Seventeen patients (0.83%) experienced an MCL injury intraoperatively, and the remaining 1732 patients (2037 knees) were considered as the controls. We attempted to reconstruct the MCL with an unconstrained prosthesis in all patients. The Knee Society Score (KSS) was used to evaluate knee function after an average 51-month follow-up (range, 36-72 months).No patients were lost during the follow-up period. In the MCL injury group, the mean KSS was 84.7 for function and 87.7 for pain, while the scores were 87.9 and 90.6, respectively, in the control group. No patient treated with MCL reconstruction without increased prosthetic constraint experienced knee instability requiring revision.MCL reconstruction without a constrained implant achieved excellent results for MCL injury during TKA. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Patella morphological alteration after patella instability in growing rabbits.

BACKGROUND: The shape of the patella has been considered to be a predisposing factor resulting in patellar instability, but the effects of abnormal patella position during its development are unclear. The present study evaluated patellar morphological changes after patella instability and evaluated the influence of patellar instability on the patella shape. METHODS: Twenty rabbits that were 2 months old were included in the study. The left knee of each rabbit, defined as the experimental group (N = 20 knees/group), underwent a medial soft tissue restraint release. The right knee of each rabbit, defined as the control group (N = 20 knees/group), did not undergo any surgical procedures. A CT scan was performed on each knee before surgery and 6 months post-surgery to measure the transverse diameter, thickness, Wiberg index, and Wiberg angle for analysis of the patellar morphological changes. Cross-specimen examination was conducted to evaluate the differences between the experimental group and the control group. RESULTS: The four indices remained the same between the two groups before surgery. However, 6 months after surgery, the mean transverse diameter of the patellae in the experimental group was significantly longer than that in the control group (P < 0.001), while the mean thickness in the experimental group was not significantly greater than that in the control group (P = 0.314), resulting in a flattened shape. The Wiberg indices were not significantly different between the two groups. However, the mean Wiberg angle was higher in the experimental group than in the control group (P < 0.001), which resulted in a flattened articular surface of the patella. CONCLUSION: The sectional shape and articular surface of the patella became more flattened after patella instability in this study, which indicates that patella dysplasia could be caused by patella instability. Clinically, early intervention for adolescent patients with patella instability is important.