Heterogeneity in patellofemoral cartilage adaptation to anterior cruciate ligament transection; chondrocyte shape and deformation with compression

OBJECTIVE: The purpose of this study was to determine if the opposing cartilages of the feline patellofemoral joint adapted differently to short-term anterior cruciate ligament transection (ACL-T) and if the magnitude of chondrocyte deformation upon tissue loading was altered under ACL-T conditions compared to contralateral controls. In situ static compression of physiological magnitude was applied to the feline patellofemoral cartilage 16 weeks post-ACL-T and cartilage and chondrocyte deformation were evaluated by histomorphometry. DESIGN: Six adult cats were euthanized 16 weeks after unilateral ACL-T. A peak surface pressure of 9 MPa was applied to the fully intact patella and femoral groove cartilages. After in situ fixation under compression, sections from the centre of the indent and from an adjacent unloaded area of the cartilages were analysed. Chondrocyte shape, size, clustering and volumetric fraction were quantified. RESULTS: Experimental patellar articular cartilage was thicker, contained larger chondrocytes that were more frequently arranged in clusters and had, on average, a larger chondrocyte volumetric fraction compared to contralateral controls. In contrast, the experimental femoral groove cartilage demonstrated little adaptation to ACL-T. CONCLUSIONS: The patellar articular cartilage adapts to short-term ACL-T to a greater extent than femoral groove cartilage. We speculate that differences in the histological parameters of control tissues, such as cartilage thickness and the magnitude and depth distribution of chondrocyte shape, size and volumetric fraction may contribute to predisposing patellar cartilage, and not femoral groove cartilage, to adaptation after ACL-T.     

Diagnosis and treatment of excessive lateral pressure syndrome of the patellofemoral joint caused by military training

Objective: To investigate the diagnosis and surgical treatment of excessive lateral pressure syndrome of the patellofemoral joint caused by military training. Methods: Fifteen patients (patient group) and 18 healthy volunteers (control group) were involved in this retrospective study. Radiographs of the knee joints of all patients and volunteers were taken. The bone architecture was assessed, the trochlear angle, coincidence angle and patellofemoral joint index measured in both groups, and the resulting data compared. All 15 patients (17 knees) were treated by lateral collateral retinaculum release. Pre‐ and post‐operative pain was evaluated with a visual analog scale (VAS). Results: The differences between the two groups in coincidence angle (patient group: 7.67°± 5.81°; control group: ?2.2°±?2.71°) and patellofemoral joint index (patient group: 2.49 ± 1.40; control group: 1.25 ± 0.15) were statistically significant. Subchondral bone sclerosis and osteophytosis in the patellofemoral joint were more pronounced in the patient group than in the control group. The VAS was higher preoperatively (7.06 ± 0.85) than postoperatively (6 months postoperatively: 3.87 ± 0.24; 1 year postoperatively: 3.01 ± 0.17), and the differences between preoperative and postoperative were statistically significant. Conclusions: Apart from the case history, typical symptoms and physical signs, X‐ray examination is the most basic way to diagnose excessive lateral pressure syndrome of the patellofemoral joint, and the patellofemoral joint index is the most reliable for diagnosis. Lateral collateral retinaculum release with a small‐incision is an effective treatment for this disease.     

Quantitative measurement of patellofemoral joint stability: force-displacement behavior of the human patella in vitro.

Patellofemoral joint instability is a common clinical problem. However, little quantitative data are available describing the stability characteristics of this joint. We measured the stability of the patella against both lateral and medial displacements across a range of knee flexion angles while the quadriceps were loaded physiologically. For eight fresh-frozen knee specimens a materials testing machine was used to displace the patella 10 mm laterally and 10 mm medially while measuring the required force, with 175 N quadriceps tension. The patella was connected via a ball-bearing patellar mounting 10 mm deep to the anterior surface to allow natural tilt and other rotations. Patellar force-displacement behavior was tested at flexion angles of 0 degrees, 10 degrees, 20 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees. Significant differences were found between the lateral and medial restraining forces at 10 mm displacement. For lateral displacement, the restraining force was least at 20 degrees of knee flexion (74 N at 10 mm displacement), rising to 125 N at 0 degrees and 90 degrees of knee flexion. The restraining force increased progressively with knee flexion for medial patellar displacement, from 147 N at 0 degrees to 238 N at 90 degrees. With quadriceps tension, the patella was more resistant to medial than lateral displacement. Our finding that lateral patellar displacement occurred at the lowest restraining force when the knee was flexed 20 degrees agrees with clinical experience of patellar instability.     

Knee – spine syndrome: correlation between sacral inclination and patellofemoral joint pain

 Low back pain is an enormous clinical and public health problem. When we use spinal instrumentation, measurements of spinal and leg alignment in the standing position are thought to be important. Knee joint pain has also become an enormous clinical problem in the increasing elderly population. However, the correlation between spinal alignment, particularly sacral inclination, and knee joint pain is not clear. We examined the correlation between lumbar lordosis, sacral inclination, and patellofemoral joint pain in elderly subjects. Three hundred and ninety-nine people aged 50–85 years were examined. Clinical findings and physical status were determined. Measurements and determination of total lordosis from L1 to S1 and sacral inclination were made from standing radiographs. The knee joints were evaluated by using the standing knee flexion angle, radiographs, and the patellofemoral (PF) joint grinding test. Thirty-nine percent of subjects were excluded because they had definite osteo-arthritis at the femorotibial joints. Fifty-eight percent of the subjects had felt low back pain within the previous 3 months, and 16% of the subjects complained of PF joint grinding pain. Sixteen percent of the subjects showed knee flexion when standing. There was a significant difference in sacral inclination between the groups with and without PF joint grinding pain (P < 0.01). Sacral inclination was approximately 5° less in the knee flexion group. A correlation between sacral inclination and PF joint pain is defined, and its prevalence in the elderly is reported. We speculate that this phenomenon is caused by changing of lumbar alignment. In addition, we think this is a new pathological concept that we call the knee – spine syndrome. Received: July 23, 2001 / Accepted: May 2, 2002     

Metabolic and biochemical abnormalities of articular cartilage induced by implantation of a sterile sheet of polyethylene in the rabbit patellofemoral joint

A polyethylene sheet was implanted in the patellofemoral joint of the right knee of the rabbit and the biochemical and metabolic changes in the articular cartilage from femoral trochleas (in contact with the implant) and femoral condyles (free of direct contact) were compared with those in their sham-operated counterparts 7, 15, and 30 days after joint implantation. The results showed that there was an increase in the water content; the extraction yields of uronic acid--, 35SO4-, and [3H]glycine-containing compounds; and the incorporation of [3H]thymidine, [3H]glycine, and 35SO4. Concomitantly, the contents of uronic acid--, hexosamine-, neutral sugars-, and hydroxyproline-containing substances decreased in the femoral trochlear cartilage and, to a much lesser extent, in the femoral condylar cartilage from implanted joints. The increased capacity of viable chondrocytes to incorporate metabolic radiolabeled precursors into newly synthesized macromolecules may represent a reparative cell response to the tissue injury induced by the implant. This is therefore a useful model for studying the response of chondrocytes to mechanical injury and tissue tolerance to intraarticularly implanted prosthetic materials.     

FrzB-2: a human secreted frizzled-related protein with a potential role in chondrocyte apoptosis

OBJECTIVE: To characterize a novel secreted frizzled-related protein (SFRP) and determine its tissue distribution at the mRNA and protein level. METHODS: The FrzB-2 gene was identified by expressed sequence tag (EST) analysis of human tissue-derived libraries. Tissue distribution of FrzB-2 mRNA was determined by Northern blot analysis and in situ hybridization. FrzB-2 protein reactivity was localized in human OA articular cartilage by immunocytochemistry, using a polyclonal antibody against a peptide sequence unique to FrzB-2. Apoptosis was detected in articular cartilage sections using Tunel staining. RESULTS: ESTs corresponding to FrzB-2 were found in osteoblast, chondrosarcoma, osteosarcoma, osteoclastoma and synovial fibroblast libraries. FrzB-2 mRNA is expressed in a number of tissues and cell types including bone-related cells and tissues such as primary human osteoblasts and osteoclastoma. In situ hybridization studies showed strong FrzB-2 mRNA expression in human chondrocytes in human osteoarthritic (OA) cartilage but negligible levels in normal cartilage chondrocytes. The FrzB-2 cDNA encodes a secreted 40 kDa protein consisting of 346 amino acids. FrzB-2 is 92. 5% identical to the rat orthologue, DDC-4, which has been shown to be associated with physiological apoptosis. FrzB-2 protein was selectively detected in human OA articular cartilage by immunocytochemistry, using a polyclonal antibody. Consistent with its potential role in apoptosis, positive FrzB-2 staining and Tunel positive nuclei staining were detected in chondrocyte clones in sections of human OA cartilage. CONCLUSION: These data suggest that FrzB-2 may play a role in apoptosis and that the expression of this protein may be important in the pathogenesis of human OA.     

Dynamic and static mechanical compression affects akt phosphorylation in porcine patellofemoral joint cartilage

Protein kinase B (Akt)–dependent signaling pathways induced by mechanical loading have been identified in a variety of tissue. However, there is no evidence for a potential regulation of Akt in cartilage mechanotransduction. This study was conducted in order to determine whether or not the Akt in chondrocytes is regulated by mechanical loading. Porcine patellofemoral joints were loaded in compression at 500 N for 150 s either dynamically at 12 Hz or 1 Hz or statically using a custom‐designed loading frame. Left‐sided knees served as intervention, right‐sided as unloaded control. Cartilage samples were harvested at different time points after mechanical loading and the phosphorylation of Akt was analyzed immunohistochemically. A downregulation of Akt phosphorylation was seen in cartilage 300 s after mechanical loading whereas Akt phosphorylation remained unchanged in unloaded specimens. In addition, regulation of Akt appeared to change with the frequency of loading, presenting different patterns in Akt phosphorylation with static and dynamic loading. Variations in Akt phosphorylation were detected through different zones of cartilage. Overall, our findings indicate that Akt signaling in porcine patellofemoral joint cartilage is dependent upon frequency of loading, cartilage zone, and the time interval between loading and cartilage harvest. It may be concluded that Akt plays a role in cartilage mechanotransduction. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:616–623, 2008     

Chondrons in cartilage: ultrastructural analysis of the pericellular microenvironment in adult human articular cartilages

A combination of scanning and transmission electron microscopy was used to investigate the morphology and ultrastructure of normal human articular cartilage sampled from adult amputation specimens. This study confirms our previous observations on canine articular cartilage, which showed middle and deep layer chondrocytes surrounded by a pericellular matrix and enclosed within a pericellular capsule composed of filamentous and fine fibrillar materials. Pores in the "felt-like" organization of the capsular weave progressively decreased in size from the inner to the outer border of the capsule. Matrix vesicles were found embedded within the capsular weave and distributed throughout the territorial matrix. It is suggested that the chondrocyte, its pericellular matrix, and capsule together constitute the "chondron," a primary functional and metabolic unit of cartilage that acts hydrodynamically to protect the integrity of the chondrocyte and its pericellular microenvironment during compressive loading.     

The use of debrided human articular cartilage for autologous chondrocyte implantation: maintenance of chondrocyte differentiation and proliferation in type I collagen gels.

Autologous chondrocyte implantation (ACI) is the most promising surgical treatment for large full thickness knee joint articular cartilage (AC) defects where cells from healthy non-weight bearing area AC are multiplied in vitro and implanted into such defects. In the routine surgical procedure for symptomatic knee full thickness AC defects, damaged AC surrounding the edge and the base of such defects is usually debrided and discarded. The purpose of this study was to examine if chondrocytes from this 'debrided' AC can proliferate, synthesize a cartilage specific matrix and thus can be used for ACI. METHODS: Biopsies were retrieved from 12 patients (debrided articular cartilage: DAC, aged 35-61) and from two autopsies (normal articular cartilage: NAC, aged 21 and 25). Chondrocytes were isolated, seeded at low density in type I collagen gels and as monolayer cultures for 4 weeks without passage. RESULTS: After 4 weeks cultures in type I collagen gels, cell proliferation from DAC (18.34 +/- 1.95 fold) was similar to cells from NAC (11.24 +/- 1.02 fold). Syntheses of proteoglycan and collagen in DAC were also similar to NAC. Newly synthesized matrices in gel cultures consisted predominantly of type II collagen as shown by immuno-labelling and SDS-PAGE followed by fluorography. Chondrocytes from 'debrided human AC' cultured at low density in type I collagen gels may be used for the ACI procedure as they provide sufficient viable cell numbers for ACI and maintain their chondrocyte phenotype as they synthesize a cartilage-like matrix.     

Structural characteristics of the collagen network in human normal, degraded and repair articular cartilages observed in polarized light and scanning electron microscopies

Objective

This study characterizes collagen organization (CO) in human normal (n = 6), degraded (n = 6) and repair (n = 22) cartilages, using polarized light (PLM) and scanning electron (SEM) microscopies.

Design

CO was assessed using a recently developed PLM-CO score (Changoor et al. Osteoarthritis Cartilage 2011;19:126–35), and zonal proportions measured. SEM images were captured from locations matched to PLM. Fibre orientations were assessed in SEM and compared to those observed in PLM. CO was also assessed in individual SEM images and combined to generate a SEM-CO score for overall CO analogous to PLM-CO. Fibre diameters were measured in SEM.

Results

PLM-CO and SEM-CO scores were correlated, r = 0.786 (P < 0.00001, n = 32), after excluding two outliers. Orientation observed in PLM was validated by SEM since PLM/SEM correspondence occurred in 91.6% of samples. Proportions of the deep (DZ), transitional (TZ) and superficial (SZ) zones averaged 74.0 ± 9.1%, 18.6 ± 7.0%, and 7.3 ± 1.2% in normal, and 45.6 ± 10.7%, 47.2 ± 10.1% and 9.5 ± 3.4% in degraded cartilage, respectively. Fibre diameters in normal cartilage increased with depth from the articular surface [55.8 ± 9.4 nm (SZ), 87.5 ± 1.8 nm (TZ) and 108.2 ± 1.8 nm (DZ)]. Fibre diameters were smaller in repair biopsies [60.4 ± 0.7 nm (SZ), 63.2 ± 0.6 nm (TZ) and 67.2 ± 0.8 nm (DZ)]. Degraded cartilage had wider fibre diameter ranges and bimodal distributions, possibly reflecting new collagen synthesis and remodelling or collagen fibre unravelling. Repair tissues revealed the potential of microfracture-based repair procedures to produce zonal CO resembling native articular cartilage structure. Values are reported as mean ± 95% confidence interval.

Conclusion

This detailed assessment of collagen architecture could benefit the development of cartilage repair strategies intended to recreate functional collagen architecture.     

健康青年人的膝关节软骨厚度3.0T MRI的定量研究

目的:探讨3.0T MRI精确测量健康青年膝关节软骨厚度为骨关节炎的定量诊断和关节置换精准截骨提供可靠的解剖参数。方法:自2013年1月至2013年12月于吉林省长春地区招募30名健康青年志愿者,男14名,女16名,年龄22~33(25.8±2.4)岁。对每名志愿者的双膝关节进行3.0 T MRI扫描,对股骨外侧髁(lateralis femoris condylus,LFC)、股骨内侧髁(medialis femorisc ondylus,MFC)、胫骨外侧平台(lateral tibial plateau,LTP)、胫骨内侧平台(medial tibial plateau,MTP)进行软骨厚度测量。结果:在LFC、MFC、LTP、MTP 4个区域中,无论青年男性或女性,左、右侧膝关节软骨厚度比较,差异均无统计学意义(P>0.05);健康青年男性与女性之间膝关节软骨厚度比较,差异有统计学意义(P<0.05)。在同一性别组,LFC软骨厚度中间较薄,前、后方较厚;MFC软骨厚度前方最薄,从前方向后方逐渐增厚;LTP软骨厚度中间最厚,后方次之,前方最薄;MTP软骨厚度前方最薄,中间、后方相对均匀且均较前方厚。结论:在我国22~33岁正常健康青年人中,性别差异可能是膝关节各个区域软骨厚度差异的重要因素。无论男性或女性健康青年人,整个膝关节软骨厚度分布不均匀,但左、右侧膝关节相同区域软骨厚度无明显差异。     

胫骨结节前内移治疗髌骨半脱位合并髌股关节骨关节病的预后因素分析

目的 :探讨胫骨结节前内移术治疗髌骨半脱位合并髌股关节骨关节病的临床效果及影响因素。方法 :对 1995年 6月～ 2 0 0 2年 11月 43例 ( 5 7膝 )诊断为髌骨半脱位合并髌股关节骨关节病的患者采用“胫骨结节前内移位 ,外侧支持带松解 ,清理钻孔术”治疗 ,并对术前和术后的主观症状、X线、改良Lysholm髌股关节功能评分进行比较。结果 :随访时间平均 3 5个月 ,主观优良率为 84%。平均改良Lysholm评分从术前 49分上升到术后 83分 ,提高了 3 4分 ,客观优良率为 81%。性别、侧别、年龄、随访时间及是否合并高位髌骨对治疗结果无明显影响。髌骨形态为WibergⅡ型与合并髌骨倾斜的患者治疗结果虽有更好的趋势 ,但无统计学差异。髌骨全关节面软骨磨损、伴有胫股关节软骨退变以及病程超过 10年的患者手术效果差。结论 :胫骨结节前内移术治疗髌骨半脱位合并髌股关节骨关节病可以获得比较满意的效果。髌骨全关节面软骨磨损 ,伴有胫股关节软骨退变以及病程超过 10年为预后差的危险因素。     

Biological reconstruction of the joint: Concepts of articular cartilage regeneration and their scientific basis

Articular cartilage injuries are common. The diagnosis of these injuries is often delayed and may lead to early osteoarthritis. Treatment depends on many factors but mainly on the stage and size of the lesion. The anatomy of articular cartilage is complex, and it is an avascular, aneural, and alymphatic structure. Recently, more emphasis is laid on its anatomy and biomechanics to understand the regeneration process of articular cartilage.     

肌内效贴配合电针治疗中老年运动爱好者髌股关节病

目的:观察肌内效贴配合电针治疗中老年运动爱好者髌股关节病的临床疗效.方法:2018年4月至2020年4月,选取62例中老年运动爱好者髌股关节病的患者,分为观察组和对照组.观察组30例,男12例,女18例;年龄35～66(48.32±6.80)岁,采用肌内效贴配合膝部取穴电针治疗.对照组32例,男12例,女20例;年龄3...     

MRI序列及三维重建在膝关节软骨损伤的诊断价值

目的观察脂肪抑制三维扰相梯度回波序列（FS-3D-SPGR）、FS-FSE-T2W序列及三维重建对软骨损伤的诊断价值。方法41个膝关节关节面共205个区域进入研究,MR检查至少包括FS-FSE-T2W、3D-FS-SPGR序列,对损伤进行分级。在工作站上采用HDMIP进行三维重建,其结果与关节镜对照。结果3D-FS-SPGR序列对软骨损伤显示的敏感度为89．47％,特异度为97．65％;FS-FSE-T2W序列的敏感度为78．57％,特异度为94．71％。结论3D-FS-SPGR能准确评价关节软骨的损伤程度,但对软骨下骨及骨髓损伤不敏感;FS-FSE-T2W能准确反应软骨下骨及骨髓损伤的程度及范围,二者结合是目前诊断软骨损伤的最佳扫描序列。关节软骨的三维重建图像能够较真实准确地显示软骨损伤的部位与范围。     

Sonography on injury of the medial patellofemoral ligament after acute traumatic lateral patellar dislocation: Injury patterns and correlation analysis with injury of articular cartilage of the inferomedial patella

Objective

The purpose of this study was to investigate the accuracy of high-frequency ultrasonography in the diagnosis of injuries of medial patellofemoral ligaments (MPFLs), analyse the characteristics of MPFL injury and correlations between injury of the MPFL and articular cartilage of the inferomedial patella in patients with acute traumatic lateral patellar dislocation.

Methods

High-frequency sonographic images of 49 patients with acute traumatic lateral patellar dislocations treated surgically were reviewed. The χ² tests were performed for statistical analysis.

Results

Twenty-eight cases of complete MPFL tear and 21 cases of partial MPFL tear were identified in operation, with 27 cases of MPFL tear located at their femoral attachment, 21 cases of tear at the patellar attachment and one case of midsubstance tear. The diagnostic accuracy of sonography regarding partial MPFL tear and complete MPFL tear was 89.8% and 89.8%. Among the patients with MPFL tear at the patellar attachment, eight and six cases were concomitant with chondral and osteochondral lesions in the inferomedial patella, respectively, in contrast to nine and six cases in patients with MPFL tear at the femoral attachment, respectively. There was no significant difference between the two locations described above regarding the prevalence rates of chondral or osteochondral lesions of the inferomedial patella (P = 0.732, P = 0.614). Among the patients with complete MPFL tear, 12 and 10 cases were concomitant with chondral and osteochondral lesions in the inferomedial patella, respectively, while six and two cases were concomitant with partial MPFL tear. There was no significant difference between the two types of injuries discussed above on the prevalence rates of chondral lesions of the inferomedial patella (P = 0.305), but the prevalence rate of osteochondral lesions between the two types of injuries discussed above was statistically different (P = 0.035).

Conclusions

The MPFL is most easily injured at the femoral attachment, secondly at the patellar attachment. High-frequency ultrasonography is an accurate method in the diagnosis of an MPFL tear. There are neither significant differences on the prevalence rates of chondral or osteochondral lesions of the inferomedial patella between locations of MPFL injuries, nor significant difference on the prevalence rates of chondral lesions between MPFL injury types; but the complete MPFL tear is more often concomitant with inferomedial patellar osteochondral lesions than the partial MPFL tear.