Radiography of the patellofemoral joint

Radiographs of the knee, and especially the patellofemoral joint, are indeed important, but they must be kept inperspective. There is a tendency for the orthopedist to rely too heavily upon the “x-ray.” Perhaps this is natural because we treat so much trauma, and the diagnostic answers, the fracture classification, and even the preferred treatment are often suggested by the initial radiograph. When it comes to patellofemoral disorders, the history, the physical examination, and the initial radiographs assume nearly equal importance, with the physical examination providing perhaps the best information to explain each patient's pathophysiology and to develop a treatment plan. The patellofemoral joint is unique, so its radiographic evaluation will be unique as well. The axial radiograph, which provides the most information, demands that the clinician know exactly what technique was used before an intelligent interpretation can be made. An understanding of the advantages and disadvantages of these different techniques, as well as an appreciation for the various radiographic measurements that separate “normal” from “abnormal,” will make the clinician's task much easier.     

Biomechanics of patellofemoral instability

The patellofemoral joint functions as a complex extensor apparatus with important biomechanical contributions provided by both articular contact and the surrounding soft tissues. The patella must remain relatively stable while tracking along the anterior and distal surfaces of the femur. If there is instability in the coronal plane (subluxation or dislocation) or around the caudocranial axis (tilt), then pain may result. Stability is maintained through the precise interaction of the patellofemoral articulating surfaces, passive and active soft-tissue restraints, and the alignment of the lower extremity. The purpose of this article is to review these biomechanical variables and how they relate to the treatment of patellofemoral instability.     

Two-dimensional knee valgus displacement as a predictor of patellofemoral pain in adolescent females

Patellofemoral pain (PFP) is a prevalent lower limb musculo-skeletal injury in adolescent females. Female athletes with PFP display increased frontal plane knee joint motion in comparison to control subjects. The current investigation aimed to determine prospectively whether two-dimensional knee valgus displacement during landing could predict the risk of developing PFP. Seventy-six injury-free adolescent female athletes (age = 12.9 ±0.35 years) participated. At baseline participants performed three drop vertical jump trials from a 31-cm box. A standard video camera was used to record frontal plane knee joint kinematics. Over the 24-month follow-up, eight participants developed PFP, as diagnosed by a Chartered Physiotherapist. Knee valgus displacement was significantly increased in those who developed PFP compared to those who did not (mean difference = 7.79°; P = 0.002; partial eta squared = 0.07). Knee valgus displacement ≥10.6° predicted PFP with a sensitivity of 0.75 and specificity of 0.85. The associated positive likelihood ratio was 5. These results have clinical utility suggesting that two-dimensional analysis could be implemented to screen for increased risk of PFP in adolescent female athletes.     

Functional anatomy and biomechanics of the meniscus

The meniscus is no longer considered the evolutionary remnant in the knee joint.Rather, it is now well established as an important structure that is integral to the complex biomechanics and proper functioning of the knee. The medial and lateral menisci form two crescent-shaped wedges of fibrocartilage between the femoral condyles and tibial plateaus.The knee joint biomechanics are based on a complex interaction of these intra-articular structures. The functions ascribed to the menisci include load transmission, shock absorption, stability, proprioception, joint lubrication, and joint nutrition. Load transmission generally is accepted as one of its primary functions. The menisci transmit a portion of the axial forces across the knee joint by converting this load into “hoop stresses.” This is accomplished by their unique shape, composition, and anatomic attachments. The menisci are relatively mobile structures and their motion during knee flexion also is determined by their shape and soft tissue attachments/constraints. Preservation of the meniscal functions is essential, and the authors review the basic anatomic and biomechanical concepts necessary to understand techniques for repair and restoration of these functions.     

军事训练所致外侧髌股挤压综合征的临床研究

目的 探讨军事训练所致外侧髌股挤压综合征的诊断方法及手术治疗效果.方法 收集2006年5月-2008年5月收治的军事训练所致外侧髌股挤压综合征患者15例(病例组),男12例(14膝),女3例(3膝),年龄22～43岁,平均27.3岁.以随机抽取的18名年龄性别匹配、无膝痛症状的健康志愿者作为对照组.两组患者均接受膝关节正侧位及髌骨轴位X线片检查,观察膝关节骨质结构情况,测量滑车角、适合角及髌股指数并进行组间比较.病例组患者均实施髌外侧支持带松解术,并对术前和术后疼痛程度(VAS法)进行评估.结果 病例组适合角(7.67°±5.81°)及髌股指数(2.49±1.40)均明显大于对照组(适合角-2.2°±-2.71°,髌股指数1.25±0.15),差异有统计学意义(P＜0.01,P＜0.05),而滑车角(132.44°±10.21°)与对照组(136.80°±4.87°)比较差异无统计学意义(P＞0.05),且病例组膝关节骨质结构改变明显.病例组术前疼痛程度评分为7.06±0.85,明显高于术后6个月(3.87±0.24)及术后1年(3.01±0.17),差异有统计学意义(P＜0.05),而术后6个月与术后1年的疼痛程度评分差异无统计学意义(P＞0.05).结论 军事训练所致外侧髌股挤压综合征的诊断需结合病史、典型临床症状、体征及X线检查并注意鉴别诊断.膝关节X线片是诊断外侧髌股挤压综合征最基本的辅助检查手段,其中髌股指数应用方便.     

髌股关节紊乱的MRI表现与临床

目的：探讨髌股关节紊乱(PFD)的MRI表现。方法：膝关节正常组6例(10个膝)及病例组42例(70个膝)受试者均行MRI检查,对病理性髌股关系及髌骨支持带的表现进行分析。结果：所有病例(70个膝)髌骨外侧半脱位程度6～15 mm,60％为双侧。其他恒定的异常包括股骨滑车发育不良、髌骨内侧支持带薄、髌外侧支持带增厚以及...     

髌骨倾斜导致髌股关节接触压力与面积改变

我们采用压敏片测量技术对髌骨倾斜状态下髌股关节的生物力学变化特点进行了研究。７例新鲜人尸体标本采用手术方法将髌外侧支持带紧缩造成髌骨外侧倾斜状态，超低压型压敏片置于髌股关节之间，等长加载２００Ｎ，分别在正常状态及髌骨倾斜状态下于屈膝３０°、６０°、９０°、１２０°时测量髌股关节接触压力与面积。结果表明：髌骨倾斜后使髌股关节原正常的“哑铃型”接触压迹转变为“彗星尾状”，外侧面孤立接触，内侧面接触区减少或失接触，接触压力改变表现为髌内侧软骨面接触压力减少或消失，外侧面接触压力集中且明显增高上述改变均以屈膝３０°时最明显。实验结果提示：各种纠正髌骨倾斜状态及治疗髌骨软骨软化症的手术方法，必须以恢复髌骨内外侧关节面压力平衡为标准，特别是屈膝３０°时病理力学的改善最为重要     

Clinical and radiological outcome of medial patellofemoral ligament reconstruction with a semitendinosus autograft for patella instability

Background: Recurrent patellar instability is a common problem after dislocation. The medial patellofemoral ligament (MPFL) contributes 40–80% of the total medial restraining forces. This study assessed the clinical and radiological outcome after a follow-up of 4 years after linear MPFL reconstruction using an ipsilateral Semitendinosus tendon autograft. Study design and methods: 15 knees in 12 patients were examined with a mean of 47 months after linear reconstruction of the MPFL at a mean age of 30 years. 3 knees underwent previous surgery. 3 patients had mild trochlear dysplasia grade I or II, according to the classification of Dejour. If preoperative tibial tuberosity-trochlear groove distance (TTTG) was more than 15 mm, patients underwent additional medialisation of the tibial tuberosity (n=8) creating a similar postoperative situation for all patients. All patients were available for a postoperative evaluation, which consisted of a subjective questionnaire, the Kujala score, and the recording of potential patellar redislocation and apprehension. Patellar height and tilt was measured on plain radiographs. Postoperative CT scans were performed in patients with an additional tibial tuberosity-transfer. Results: Postoperatively, one patient reported on recurrent bilateral redislocation. Physical examination however revealed no findings. Three knees presented with persistent patellar apprehension. Thirteen knees had improved subjectively after surgery. The mean Kujala score improved significantly from 55.0 to 85.7 points. The patellar tilt decreased significantly from 11.3° to 9.2°. Four knees had patella alta preoperatively, but only two at the latest follow-up visit. Previous surgery or additional trochlear dysplasia had no influence on the clinical outcome. Conclusion: MPFL reconstruction improves clinical symptoms, reduces the patellar tilt substantially, and may correct patella alta. Additional mild trochlear dysplasia did not compromise the outcome; however, this fact needs further attention in a larger study group.     

Anatomical analysis of the medial patellofemoral ligament of the knee, especially the femoral attachment

The purpose of this study was to investigate the anatomical morphology and measurement of the medial patellofemoral ligament (MPFL), especially the femoral attachment. A total of 20 knee specimens were dissected and the total length, width, thickness, inclination, as well as the attachment points of the MPFL were measured. The MPFL was well-developed in seven knees, moderate in ten knees and wispy in three knees. Total length of the MPFL was 58.8 ± 4.7 mm. The width and thickness was 12.0 ± 3.1 mm and 0.44 ± 0.19 mm at the middle point. The long axis of the MPFL inclined at 15.9 ± 5.6° proximally. The center of the patellar attachment was located at 27 ± 10% from the upper end of the patella in the longitudinal patellar height. The femoral attachment was superoposterior to the medial femoral epicondyle and just distal to the adductor tubercle. The center of the anterior edge of the femoral attachment was 9.5 ± 1.8 mm proximally and 5.0 ± 1.7 mm posteriorly from the center of the medial femoral epicondyle. The femoral attachment was located at 61 ± 4% of anteroposterior length of the medial femoral condyle from the anterior edge.     

Medial patellofemoral ligament reconstruction using a hamstring graft

Recurrent lateral dislocation of the patella has been historically treated with a combination of multiple techniquesincluding lateral release, proximal realignment, medial reefing, and distal realignment. Poor-quality medial retinacular tissues and nonanatomic surgical attempts to restrain the patella may contribute to notable problems with redislocation and anterior knee pain. Recent biomechanical studies have identified the functional importance of the medial patellofemoral ligament as the primary restraint to lateral translation of the patella. A technique of reconstruction of this ligament with a single semitendinosis autograft, which provides a sturdy check-rein to lateral translation, is described. The authors' current indications for this procedure are (1) the recurrent lateral patellar dislocations in a patient with poor-quality medial soft tissues and no definable MPFL, and (2) the failure of previous proximal or proximal and distal realignment procedures with continued medial functional deficiency.     

Q角对髌股关节接触力学的影响

本研究应用染色法和压敏片法,对8例新鲜尸体膝关节在不同Q角和屈膝角度时的髌股接触部位、面积和应力分布进行测试。结果表明:在生理Q角状态下,随着屈膝角度的增大,髌股接触从髌后关节面下极逐渐向上极移行,接触面积也逐渐增大,接触应力呈渐进缓慢增加:并在屈膝80°—90°时出现腱股接触现象,这种现象对保护关节软骨,避免局部软骨压力过高有重要意义。Q角改变后,接触区向内或向外侧偏移,接触面积无明显改变,但接触应力变化显著。作者认为异常的Q角是导致髌股疾病的一个潜在因素,无论是手术矫治还是运动员选材时都应予以重视。     

人类髌股关节三维运动规律的研究

本实验通过精密机械式三维位移测量方法，采用１０条新鲜离体人膝关节标本定标加载，分析研究了屈膝过程中的髌股关切运动学及Ｑ角变化对髌股关节运动的影响。结果发现，人类髌股关切具有复杂而有规律性的三维运动特点，对传统认为“髌骨具二维运动”的观点提出了修正。同时发现，Ｑ角异常增大或减小，虽然对髌股运动趋势无显著影响，但可影响髌股运动幅度从而影响髌股稳定性。髌骨的许多特征运动均发生在屈膝３０°之前，髌骨此时也最不稳定，容易受到伤害提示临床手术治疗、护具设计及运动员选材时应予重视。     

Osteochondritis dissecans of the patellofemoral joint

Osteochondritis dissecans of the patellofemoral joint is an uncommon condition that may be the cause of anterior knee pain or crepitus. We present the clinical features of 37 patients with osteochondritis dissecans lesions of the patellofemoral joint (24 on the patella, 13 on the trochlear groove), including two patients with medial trochlear groove lesions, which have not, to our knowledge, been previously reported. The osteochondral lesions involved the convex articular surfaces. The median age of patients when first examined was 15 years, and 54% of patients had open epiphyses. These lesions were more common in male patients than in female patients (four-to-one ratio). Osteochondritis dissecans of the patellofemoral joint can be overlooked unless quality radiographs are viewed with care and, at arthroscopy, both the patella and trochlear groove are assessed. Treatment depends on the symptoms, site, and nature of the lesion and the patient's age. Nonoperative management includes patellar taping and vastus medialis obliquus muscle exercises. Operative intervention is indicated for patients with mechanical symptoms and includes arthroscopy, consisting of chondroplasty and removal of loose bodies, and lateral retinacular release. In this study treatment generally improved the symptoms, but patients with articular cartilage loss had persistent patellofemoral crepitus and discomfort.     

Early osteoarthritis of the patellofemoral joint

Patellofemoral joint cartilage lesions are associated with a variety of clinical situations including blunt trauma, lateral patella dislocations, or as a secondary development in the setting of abnormal joint loading. There is a need for more clarity on how to best address these lesions. Most specifically, when is it necessary to surgically treat these lesions of the patella and trochlea and which technique to use? This review will focus on the spectrum of patellofemoral disease/injury and their treatment strategies, with special emphasis on cartilage damage and early osteoarthritis. Chapter sections will review the most common scenarios of cartilage damage in the patellofemoral joint, with an attempt to summarize current treatment, their outcomes, remaining challenges and unanswered questions. Level of evidence V.     

The influence of medial patellofemoral ligament reconstruction on clinical results and sports activity level

Objectives: The aim of this study was to demonstrate postoperative outcomes and return to regular physical and sports activities at average of 6 years after patellar stabilization with medial patellofemoral ligament (MPFL) reconstruction.

Methods: Between November 2006 and January 2010, 31 isolated MPFL reconstructions in 29 patients with recurrent patellar dislocation were performed. Radiographs and magnetic resonance imaging were evaluated preoperatively. Knee function was assessed pre- and postoperative using Kujala score and the patient satisfaction, according to the International Knee Documentation Committee (IKDC) score. Tegner activity score was used for the evaluation of sports activity level.

Results: The average follow-up was 6.4±1.2 years. All measured scores increased significantly at follow-up. The average Kujala score increased from 75±10 to 95±10, patient satisfaction according to IKDC score from 6.1±1.4 to 8.7±1.4 and Tegner activity score from 4.4±1.6 to 5.7±1.3. The Tegner activity score after surgery was significantly lower than the score before the patellar dislocation (6.7±1.3). There were no significant differences in Kujala postoperative score between women’s and men’s group (P=0.25). There was no significant correlation between body mass index and Kujala score postoperatively (P=0.11) and between age at surgery and Kujala scores postoperatively (P=0.56). Patients who were active in sports preoperatively had resumed sports activities in 88.5% after surgery, 69.6% of them returned to the same levels and 30.4% return to the lower levels.

Conclusion: Patellar stabilization with MPFL reconstruction is a safe and effective treatment method for all patients with patellofemoral instability and allows most patients to return to regular physical and sports activities after surgical intervention. Although sports activity level increased significantly after surgery, the same level of sports activity before the patellar dislocation has not been achieved.     

髌骨骨折的生物力学研究及其治疗现状

髌骨骨折治疗原则是充分恢复髌骨的功能;髌骨切除术治疗后,常发生不同程度的关节软骨退变;接骨术的内固定方法较多,金属张力带固定是较理想的固定方法,但术后可能有针尾触痛、刺破皮肤等并发症,还需Ⅱ期手术。选择生物材料固定正在研究发展之中。     

新型胫骨动力型交锁髓内钉的生物力学研究

目的：设计胚骨动力型交锁髓内钉与静力型交锁髓内钉进行生物力学比较。方法：将胫骨标本制成四组实验模型。甲组：动力固定，粉碎性骨折；乙组：动力固定，斜形骨折；丙组：动力固定，横断骨折；丁组：静力固定，粉碎性骨折。将各级标本进行轴向加压试验及扭转试验。结果：各组压缩试验相差显著，扭转试验相差不显著，压缩试验曲线表明用新型胚骨动力型交锁髓内钉固定后抗压能力强，骨折端有一定应力存在。结论：胚骨动力型交锁髓内钉固定良好，骨折端有压应力存在，有利于骨折愈合。