青少年与成人急性髌骨外侧脱位后内侧髌股韧带损伤的MRI对比分析

目的 对比分析青少年与成人急性髌骨外侧脱位后内侧髌股韧带(MPFL)损伤的MRI特点.方法 分别对42例青少年和45例成人急性髌骨外侧脱位患者的MRI资料进行回顾性分析,87例患者均行常规MRI矢状面、冠状面和横断面T1 WI、T2WI、脂肪抑制FSE双回波序列扫描,分析MPFL的损伤特点,并应用x2检验比较青少年和成人MPFL各种损伤的发生率.结果 急性髌骨外侧脱位后,青少年组MPFL损伤发生率为97.6％ (41/42),其中完全撕裂、部分撕裂发生率分别为57.1％ (24/42)、40.5％(17/42);成人组对应的MPFL损伤发生率、完全撕裂发生率、部分撕裂发生率分别为100.0％ (45/45)、64.4％(29/45)、35.6％ (16/45);2组间MPFL损伤的发生率差异均无统计学意义(x2值分别为1.084、0.486、0.223,P值均＞0.05).青少年组MPFL股骨侧、髌骨侧、体部撕裂发生率分别为31.0％(13/42)、78.6％(33/42)和26.2％(11/42),其中多发部位损伤发生率为33.3％ (14/42);成人组对应的各发生率分别为64.4％(29/45)、40.0％(18/45)、15.6％(7/45)和15.6％ (7/45),2组间比较MPFL股骨侧、髌骨侧撕裂发生率差异有统计学意义(x2值分别为9.759、13.324,P值均＜0.05),体部撕裂发生率差异无统计学意义(x2=1.497,P＞0.05).青少年组较成人组尽管多发部位损伤差异无统计学意义(x2=3.749,P＞0.05),但青少年组更易伴发MPFL多发部位损伤.结论 青少年与成人比较,急性髌骨外侧脱位后MPFL损伤程度分布无差异,但在损伤部位分布上,二者具有显著差异,成人组损伤以股骨侧多见,其次为髌骨侧,而青少年组以髌骨侧多见,其次为股骨侧,青少年更易发生MPFL多发部位损伤.     

The influence of the lower patellar pole in the pathogenesis of chronic patellar tendinopathy

Resection of the lower patellar pole provides good results in the treatment of jumper’s knee. Therefore we hypothesized that the length of the lower patellar pole is increased in patients with chronic patellar tendinopathy. Cohort study, level of evidence 2. Between 2000 and 2005, 25 patients with chronic patellar tendinopathy underwent conservative and surgical treatment in our clinic. All of them had preoperative MRI were three independent examiners measured the Caton Index, the length and the ratio of the articular and non-articular patellar surface, tendon length and thickness and the thickness and length of the hypodens lesions in the patellar tendon. The measurements were compared with 50 MRI of a control group with no clinical patellofemoral disorders or patellar tendinopathy. Significant changes in tendon thickness (9.42 ± 2.87 vs. 4.88 ± 1.13; P < 0.0001), a longer non-articular surface of the patella (10.62 ± 2.86 vs. 7.098 ± 2.53; P < 0.0001) and significant higher ratio between the articular and the non-articular patellar surface (0.32 vs. 0.24; P < 0.0001) were found in the jumper’s knee group. No significant changes were seen in the length of the articular surface or the Caton Index. The development of chronic patellar tendinopathy in athletes might be associated with a longer lower patellar pole as patients with jumper’s knee showed a longer non-articular patellar surface compared with the control group.     

Factors of patellar instability: An anatomic radiographic study

We analyzed the radiographs and computed tomography (CT) scans of 143 knees operated on for symptomatic patellar instability and 67 contralateral asymptomatic knees, togcther with 190 control knee radiographs and 27 control knee scans, to determine the factors affecting patellar instability. Four factors were relevant in knees with symptomatic patellar instability: (1)Trochlear dysplasia (85%), as defined by the crossing sign (96%) and quantitatively experessed by the trochlear bump, pathological above 3 mm or more (66%), and the trochlear depth, pathologic at 4 mm or less. (2)Quadriceps dysplasia (83%), defined as present when the patellar tilt in extension is more than 20% on the CT scans. (3)Patella alta (Caton-Deschamps) index greater than or equal to 1.2 (24%). (4)Tibial tuberosity-trochlear groove, pathological when greater than or equal to 20 mm (56%). The factors appeared in only 3%–6.5% of the control knees. The etiology of patellar instability is multifactorial. Determination of the factors permits an effective elective therapeutic plan which aims at correcting the anomalies present.     

Evaluation of patellar tracking in symptomatic and asymptomatic individuals by magnetic resonance imaging

Objective To determine the patterns of patellar motion in subjects without knee symptoms using dynamic magnetic resonance imaging (MRI).Design Patellar tracking MR examinations were performed on 50 asymptomatic volunteers. The presence and degree of lateral subluxation and tilt of the patella was assessed independently by three radiologists, and discrepancies resolved by consensus. Using the same criteria, the tracking pattern in 50 consecutive patients, recently referred for imaging assessment of anterior knee pain, was studied.Patients Fifty volunteers (22 male, mean age 37 years) and 50 unmatched patients (15 male, mean age 25.5 years) were examined.Results and conclusions Forty-one per cent of a total of 97 knees in the volunteer group showed evidence of lateral subluxation, which was either minimal (grade 1, 32%) or minor (grade 2, 9%). No volunteer demonstrated major (grade 3) subluxation; lateral tilt without translation of the patella was also seen (2%). In the patient group, higher grades of lateral subluxation were more common. Minimal (grade 1) lateralization is a common movement pattern of the patella on knee extension, and should be regarded as normal.     

Superolateral Hoffa's Fat Pad Edema and Trochlear Sulcal Angle Are Associated With Isolated Medial Patellofemoral Compartment Osteoarthritis

Purpose

To evaluate whether mediopatellar plica and knee morphometric measurements obtained from magnetic resonance imaging (MRI) studies are associated with isolated medial patellofemoral osteoarthritis in young adults.

Patellar polyethylene peg fracture: a case report and review of the literature

The patellar component of a total knee replacement (TKR) is the most frequent source of non-septic complications after total knee arthroplasty. Fracture of patellar pegs in all polyethylene patellar components is a very rare occurrence. We report such a case of a patellar polyethylene fracture in a 72-year-old female patient 10 years after TKR. Due to patellar malalignment and high level of activity, the patellar components failed in this patient. This was treated arthroscopically by removing the components that failed and leaving the patella unresurfaced. We followed up the patient postoperatively and her symptoms were substantially resolved.     

Patients with lateral tracking patella have better pain relief following CT-guided tuberosity transfer than patients with unstable patella

In patients with either lateral tracking patella or unstable patella the pathological lateral position of the tuberosity can be corrected by a medial transfer. This study compared the results of subtle CT-guided correction of the tuberosity for objective unstable patella (n=27) with the results for lateral tracking patella (potential instability) as described by Dejour (n=16). Follow-up was 37 months. CT revealed a pathological lateralization of the tibial tuberosity–trochlear groove greater than 15 mm in 41 knees. These patients underwent medialization of the tibial tuberosity up to 10–12 mm lateral from the trochlear groove, and 28 patients underwent a distalization to normalize the Caton index to 1.0–1.2. Results were evaluated using Cox' method. Patients with objective patellar instability were rated as 11% excellent, 52% good, 33% fair, and 4% poor. All patients became stable except one who had a 6° valgus alignment. Although 96% had improved stability, 33% of the patients still had pain. The patients with lateral tracking patella (potential instability) were rated as 37.5% excellent, 44% good, and 19% fair. The lower proportion of pain relief in patients with unstable patella is likely the result of the cartilage damage experienced by these patients following multiple dislocations. Thus the patient with lateral tracking patella without patella dislocations must be differentiated from the one with unstable patella. Their prognosis in pain relief is better.     

Functional MRI of the patellofemoral joint: comparison of ultrafast MRI,motion-triggered cine MRI and static MRI

In recent years ultrafast gradient echo sequences have been used in MRI that allow functional MRI studies of the joints during active motion in an acquisition time of seconds. To evaluate the feasibility and usefulness of ultrafast MRI (u), patellar tracking from 30° of flexion to knee extension (0°) was analysed and compared with motion-triggered cine MRI (m) and a static MRI technique (s). The different imaging methods were compared in respect of the patellofemoral relationship, the examination time and image quality. Eight healthy subjects and four patients (in total 18 joints) with patellar subluxation or luxation were examined. Significant differences between the static MRI series without quadriceps contraction and the functional MRI studies (motion-triggered cine MRI and ultrafast MRI) were found for the patellar tilt angle (PTA: P _m/s = 0.01; P _u/s < 0.01). In the dynamic joint studies there was no statistical difference of the regression coefficients between the motion-triggered cine MRI studies and the ultrafast MRI studies (P _m/u = 0.8). The findings of the functional MRI studies compared with the static MRI images were significantly different for the lateralisation of the patella, expressed by the lateral patellar displacement (LPD: P _m/s < 0.01; P _u/s = 0.01) and bisect offset (BSO: P _m/s = 0.01; P _u/s < 0.05). No significant differences in patellar lateralisation were found between motion-triggered cine MRI and ultrafast MRI (LPD: P _m/u = 0.89; BSO: P _m/u = 0.33). Ultrafast MRI was superior to motion-triggered cine MRI in terms of the reduction in imaging time and improvement of the image quality. Correspondence to: C. Muhle     

Minimal rotation aberrations cause radiographic misdiagnosis of trochlear dysplasia

Radiologic criteria are commonly used to diagnose femoral trochlear dysplasia causing patellofemoral (sub)luxations. A dysplastic trochlea can be identified on conventional radiographs when the line of the trochlear groove crosses the anterior border of one or both condyles. The aim of this study was to establish the influence of rotation on the precision of these radiographic criteria as classified on a true lateral conventional radiograph. In a radiological in vitro study using two different distal femurs we found that rotation deviations of the distal femur can simulate femoral trochlear dysplasia in a normal knee. In case of trochlear dysplasia, rotational deviations can simulate a normal trochlear shape with crossing of the trochlear groove with the anterior border of the femoral condyle. Even a rotation deviation of 5° can cause a false-positive or false-negative diagnosis. We recommend the use of fluoroscopy to obtain a true lateral view (with both condyles overlapping on the posterior side) in order to correctly classify trochlear dysplasia and would strongly urge that no surgery should be performed on the basis of rotated conventional radiographs.     

Measurement of coronal plane patellar mobility in normal subjects

This study evaluated an instrument for measuring patellar mobility in the coronal plane in normal subjects, established baseline quantitative data and compared with methods of measurement described in the literature. This data can be used as a baseline for clinical assessment of patellar mobility. The findings suggest that 8-20 mm displacement is normal patellar mobility in the coronal plane. Displacement less than 8 mm may be considered as retinacular tightness and displacement greater than 20 mm considered as abnormal retinacular laxity. Received: 11 December 1998/Accepted: 1 October 1999     

Patellar dislocation has predisposing factors

One hundred patients with the diagnosis of an acute patellar dislocation treated conservatively and 30 healthy control subjects were studied roentgenographically by lateral and tangential views. The aim of the study was to determine the distribution and incidence of predisposing factors in different study groups. Three study groups were formed as follows: 67 patients (group A) without late problems or operative treatment of redislocation: 33 patients (group B) who underwent a surgical realignment procedure for redislocations or late problems; and 30 healthy control subjects (group C). A statistically significant difference was observed between the patient groups (A, B) and control group (C) when the means, medians and distributions of patellar tendon length (LT), patellar length (LP), tendon to patellar length ratio (LT/LP), tendon to patellar articular surface ratio (LT/LAS), sulcus angle (SA), lateral patellar displacement (LPD), lateral patellofemoral angle (LPA) and morphological classification of the patella (1–5, Jägerhut) were compared. In group A, LPD was also significantly greater than in group B. This study demonstrates a considerably high rate of predisposing factors associated with patellar dislocation.     

Patellar tendon length after anterior cruciate ligament reconstruction: a comparative magnetic resonance imaging study between patellar and hamstring tendon autografts

Patellar tendon shortening after anterior cruciate ligament reconstruction may be associated with anterior knee pain or patellofemoral arthritis. The present study was designed to compare postoperative changes in patellar tendon length after anterior cruciate ligament reconstruction between patellar tendon and hamstring tendon autograft. Magnetic resonance images of both knees (operated and healthy) and functional outcome were documented at least 1 year postoperatively in 16 patellar tendon harvested patients and in 32 hamstrings harvested patients. Patellar tendon length, patella length and Insall–Salvati ratio were measured. The operated knee values were compared to the respective values of the non-operated control knees. A significant 4.2 mm or 9.7% patellar tendon shortening in patellar tendon group and a non-significant 1.14 mm or 2.6% shortening in hamstrings group was detected. No significant difference was detected in terms of major shortening—patella baja—(6% for the patellar tendon group vs. 0% for the hamsting group). There was no significant difference in anterior knee problems between the two groups as evidenced by the Shelbourne score (94 for the patellar tendon group vs. 98 for the hamsting group). Harvesting of the patellar tendon for anterior cruciate ligament reconstruction resulted in a significant shortening of the remaining tendon. In contrast harvesting of the hamstring tendons did not affect significantly the patellar tendon length. However, the incidence of patella baja and overall functional outcome was not significantly different between the two groups. Paper presented at the 12th ESSKA 2000 Congress, Innsbruck, Austria, 2006 and also presented at the 5th Biennial ISAKOS Congress, Hollywood, FL, USA, 2005.     

Surgical treatment of patellar tendinitis

Patellar tendinitis is an overuse syndrome affecting the origin of the patellar tendon and its underlying part. Ultrasonography is useful to investigate tendinous pathology. It describes the anatomical lesions and their extent. Surgical excision of irreversible lesions, demonstrated on ultrasonography, is a logical attitude which provides good results.     

髌骨位置的CT几何测量——对髌骨移位角的初步研究

目的:为在横断面上评价膑骨位置,本文提出膑骨移位角(PSA)作为CT上髌骨位置的测量指标.材料和方法:对42例80个正常膝关节和11例18个膑骨半脱位膝关节CT的不同层面上的膑骨倾斜角(PTA)、髌骨外移距离(LPD)、髌骨二分比例(BSO)和PSA进行测量.对比这些参数的测量重复性,探讨PSA的价值.结果:正常组:PSA各平面平均相差0.4°,脱位组:PSA各平面平均相差1.2°.PSA各平面平均值相差不显著(P>0.05).而膝关节CT的不同平面上的PTA,LPD和BSO平均测量值有较大差异,各平面测量值之间相差显著(P<0.05).说明PSA较其它测量参数有更好的测量重复性.正常组PSA(平均7.6°)与脱位组PSA(平均13.6°)比较前者小(P<0.05).结论:作者认为PSA在膝关节不同平面之间有较好的重复性,作为横断面上估价髌骨位置的指标是有意义的.     

Dorsal defect on a multi-partite patella: imaging findings

Coincidence of dorsal defect on a multipartite patella constitutes a rare cause of anterior knee pain in the first decades of life. Imaging findings of this uncommon symptomatic skeletal variant are discussed, with emphasis on MR features.     

Imaging patellar complications after knee arthroplasty

The purpose of this study is to describe complications affecting the patella in patients with total or partial knee arthroplasty. We respectively analysed plain-film radiographs, as well as ultrasound images when acquired, in a consecutive series of 1272 patients. The mean interval from knee replacement to patellar complications was 5 years and 7 months (range, 5 months to 14 years). The complications described include fracture, instability, dislocation or luxation, necrosis of the patella, infection of the patella, erosion of the patella, patellar impingement on the prosthesis and patellar or quadricipital tendon tear. We discuss the pathological imaging findings in the patella and their differential diagnosis after knee arthroplasty. Patellar complications after knee arthroplasty are uncommon but often potentially serious.     

关节镜下手术治疗膝关节前交叉韧带急性损伤

目的 探索关节镜下微创诊断、修复与重建急性膝关节前交叉韧带（ACL）的方法 。方法 对356例ACL急性损伤的患者施行早期关节镜治疗,关节镜下采用自体中1/3髌韧带两端带骨块（B-PT-B）重建前交叉韧带,随访2年,采用Lysholm评分系统评价效果。结果 平均随访2年,Lysholm评分由术前平均40±6分提高到术后平均80±9分。结论 ACL急性损伤时,早期施以关节镜手术,创伤小,可同时处理合并伤,对于早期稳定膝关节有重要的作用。