Altered tibiofemoral joint contact mechanics and kinematics in patients with knee osteoarthritis and episodic complaints of joint instability

Background

To evaluate knee joint contact mechanics and kinematics during the loading response phase of downhill gait in knee osteoarthritis patients with self-reported instability.

Methods

Forty-three subjects, 11 with medial compartment knee osteoarthritis and self-reported instability (unstable), 7 with medial compartment knee osteoarthritis but no reports of instability (stable), and 25 without knee osteoarthritis or instability (control) underwent Dynamic Stereo X-ray analysis during a downhill gait task on a treadmill.

Findings

The medial compartment contact point excursions were longer in the unstable group compared to the stable (P = 0.046) and the control groups (P = 0.016). The peak medial compartment contact point velocity was also greater for the unstable group compared to the stable (P = 0.047) and control groups (P = 0.022). Additionally, the unstable group demonstrated a coupled movement pattern of knee extension and external rotation after heel contact which was different than the coupled motion of knee flexion and internal rotation demonstrated by stable and control groups.

Interpretation

Our findings suggest that knee joint contact mechanics and kinematics are altered during the loading response phase of downhill gait in knee osteoarthritis patients with self-reported instability. The observed longer medial compartment contact point excursions and higher velocities represent objective signs of mechanical instability that may place the arthritic knee joint at increased risk for disease progression. Further research is indicated to explore the clinical relevance of altered contact mechanics and kinematics during other common daily activities and to assess the efficacy of rehabilitation programs to improve altered joint biomechanics in knee osteoarthritis patients with self-reported instability.     

Clinical biomechanics of instability related to total knee arthroplasty

Background

Tibiofemoral instability is a common reason for total knee arthroplasty failure, and may be attributed to soft tissue deficiency and incorrect ligament balancing. There are many different designs of implant with varying levels of constraint to overcome this instability; however there is little advice for surgeons to assess which is suitable for a specific patient, and soft tissue balance testing during arthroplasty is very subjective.

Method

The current theories on primary and secondary soft tissue restraints to anterior/posterior, varus/valgus, and internal/external rotational motion of the knee are discussed. The paper reviews biomechanics literature to evaluate instability in the intact and implanted knee.

Findings

The paper highlights important intra- and extra-capsular structures in the knee and describes the techniques used by clinicians to assess instability perioperatively. In vitro cadaveric studies were found to be a very useful tool in comparing different implants and contributions of different soft tissues.

Interpretation

In vitro cadaveric studies can be utilised in helping less experienced surgeons with soft tissue releases and determining the correct implant. For this to happen, more biomechanical studies must be done to show the impact of release sequences on implanted cadavers, as well as determining if increasingly constrained implants restore the stability of the knee to pre-deficient conditions.     

The influence of vertebral instability on peridural circulation and concomitant peridural fibrosis formation

An animal model of vertebral instability was used to analyze the effect of chronic lumbar instability on the peridural vasculature and fibrosis formation. Fifty mature male domestic rabbits were divided into five equal groups. The vertebral instability was performed by excision of supra and interspinous ligaments between L2-L3 and L3-L4, excision of transverse and spinous processes and making bilateral laminectomies and facetectomies in groups I, II, III and IV. In group V only para vertebral muscle dissection was performed without vertebral instability. The simulation of the long term effects of overuse model on unstable spines (chronic instability) were performed with the use of Electrical Neuromuscular Stimulator to simulate cyclic flexion–extension movement in groups I, II. The rabbits in group I and III were sacrified for the histological evaluation at postoperative fifth day. The rabbits in groups I II, IV and V were sacrified at postoperative 21st day. There was no peridural venous endothelial injury or stasis but there was an increased amount of polymorph nuclear leukocytes in both group I (unstable-overuse) and group III (unstable-no overuse) after sacrification at postoperative fifth day. Peridural fibrosis and also vascular changes with different grades were seen in group II, VI and V after sacrification at postoperative 21th day. The grade of the venous changes and the mean amount of peridural scar formation were prominently higher in group II (unstable-overuse) than in group IV (unstable-no overuse) and V (control group). There was no difference between group IV and V for peridural scar formation and vascular changes. In conclusion, the instability of the lumbar spine with overuse could be a cause of peridural venous circulatory impairment, resulting in fibrosis formation.     

颈椎病患者突出椎间盘周围的炎症反应及临床意义

目的：观察颈椎病患者突出椎间盘周同组织的病理表现，并探讨其临床意义。方法：79例颈椎病患者手术切除100个突出的椎间盘；取出间盘周围的绀织进行HE染色及免疫绀化染色。将染色结果结合其临床表现、影像学资料进行分析。结果：45个(45％)突出间盘周围的组织内可见血管增生、炎症细胞浸润：炎症组与无炎症组患者在病程、术后脊髓功能改善方面存在显著性差异；炎症反应与颈椎不稳定之间存在显著相关性。结论：(1)部分颈椎病患者突出椎间盘周围组织内存在慢性炎症反应，炎症浸润细胞多为单核-巨噬细胞及淋巴细胞；(2)颈椎不稳定可能是造成突出椎间盘周围组织内炎症反应的原因之一；(3)慢性炎症因素可能参与了颈椎病的发病。     

激光焊点对金瓷界面结合的影响

目的:通过激光焊点对金瓷界面结合的影响分析与临床评价,探讨激光点焊技术在固定修复中的应用价值。方法:用Herapuls激光点焊机对200例存在缺陷的冠桥行点焊修补,再行烤瓷修复。结果:200例不同材料、不同缺陷原因的问题冠桥,经分类点焊修补调整后,均取得满意的修复效果。经1a随访,无焊接点处崩瓷、断裂。结论:激光点焊对金瓷界面修复无直接影响,此技术可以解决冠桥制作中的常见问题。     

内、外固定联合治疗不稳定性骨盆骨折

目的：探讨内、外固定联合治疗不稳定性骨盆骨折的临床疗效。方法：32例不稳定性骨盆骨折采用内、外固定联合治疗。结果：本组32例患者随访3～18个月,平均随访12.5个月,骨折均愈合,疗效满意,优良率为93.8%,并发症少。结论：内、外固定联合治疗不稳定性骨盆骨折,有助于治疗休克,疗效满意,并发症少,值得临床推广应用。     

Chromosomal and genetic imbalances in synovial sarcoma detected by conventional and microarray comparative genomic hybridization

Purpose: To analyze the relationship between chromosomal instabilities and clinicopathological factors in synovial sarcoma (SS). Methods: Twenty-two fresh-frozen SS were analyzed by metaphase comparative genomic hybridization (CGH). Additional microarray CGH was performed in 13 cases. Results: Fourteen patients with SYT–SSX1 rearrangements and nine patients with biphasic tumor subtypes had better prognosis than the eight patients with SYT–SSX2 rearrangements and 13 patients with monophasic subtypes, respectively. Gains (average 3.0) were more frequent than losses (average 1.0). Frequent gains were identified on chromosomal regions 2, 6q, 7, 8q, 12, 17q, 18q, and 21q, whereas frequent losses were over-lapped on chromosomes 1p31–p35, 3p, 6q, 16, and 17p. High-level gains were observed on chromosomes 1q21–q31, 7, 8, 12, 17q, 18q, and 21q. Thirteen monophasic and nine biphasic tumors had an average of 5.1 and 2.8 aberrations, respectively. Patients with tumors harboring numerous aberrations (≥3) had a worse clinical course. Microarray CGH more specifically detected genetic imbalances including gains in MDM2, MSH2, KCNK12, DCC, CDK2, ERBB3, SAS, and CDK4 and losses in HRAS, RASSF1, and CCND1. Gain of SAS was an important prognostic factor of SS. Conclusion: We have identified several factors influencing the prognosis of SS patients by metaphase and microarray CGH.     

Fractures of the tibial spine: epidemiology and outcome

We documented functional outcome in 83 knees with tibial spine fractures. The mean age at injury was 35 years. There was a medial collateral ligament sprain in 17 knees and posterolateral corner injury in three knees. Twenty patients with displaced tibial spine fractures were treated with fixation of the tibial spine and 63 patients with undisplaced or minimally displaced fractures were treated non-operatively.

Fourteen (22%) non-operatively treated knees developed symptomatic instability, three of which underwent ACL reconstruction. Tibial spine fixation restored stability in 18 of 20 knees, but knee stiffness was more common in this group when compared to non-operatively treated knees (60% vs 19%, p < 0.0005). Patients with postoperative knee stiffness had a mean age of 28 years compared to 18 in patients with no knee stiffness (p < 0.05).

We concluded that tibial spine fracture in skeletally mature patients is associated with a significant risk of knee stiffness and instability.     

关节镜指导下锚钉固定自体游离股薄肌腱加强内侧髌股韧带治疗髌骨不稳定

目的:探讨关节镜指导下锚钉固定自体游离股薄肌腱加强内侧髌股韧带治疗髌骨不稳定的手术方法和临床疗效。方法:1997年5月~2010年10月经临床和关节镜诊断的髌骨不稳定患者46例(49膝),A组在行膝关节支持带外侧松解、内侧紧缩的基础上,配合胫骨结节内移的综合术式治疗;B组在行膝关节支持带外侧松解基础上,配合锚钉固定自体游离股薄肌腱加强内侧髌股韧带的综合术式治疗。结果:随访15~87个月(平均39个月),A组优良率93.3%;B组优良率92.3%。按照Lysholm法评估膝关节功能,两组术后平均得分与术前比较均有显著性差异(P<0.001)。结论:关节镜指导下锚钉固定自体游离股薄肌腱加强内侧髌股韧带治疗髌骨不稳定可恢复髌股关节稳定性,手术方式简单、创伤小、效果好,是治疗髌骨不稳定的理想方法。