The patellotrochlear index: a new index for assessing patellar height

The radiological methods to determine patellar height described in the literature are variable, not reliable and depend on the chosen ratio. The purpose of this paper is to describe another method of measuring patellar height on sagittal MRI using the true articular cartilage patellotrochlear relationship. An analysis of magnetic resonance (MR) examinations of 66 consecutive patients was performed. The most common diagnoses were meniscal or anterior cruciate ligament pathologies. No patient suffered from patellofemoral complaints. Measurements on sagittal MR images included different parameters using the articular cartilage of the patella and the trochlea. The ratio patella : trochlea of the cartilage baselines was measured in percentages and described as patellotrochlear index. The measurements were assessed at two different times by three raters under blinded conditions. The mean patellotrochlear index was 31.7% (CI: 12.5–50.0; range −5.0 to 61.1%; SD ±11.6). The intraobserver variability showed only in the “second observer” a difference of the mean values of the two different measurements (t=2.189; P=0.032). The interobserver correlation was high and significant (0.663–0.893; P=0.000). Our results indicate that the patellotrochlear index is a reliable and precise method to determine the exact articular correlation of the patellofemoral joint and the patellar height. The results represent the average patellotrochlear index in the normal population without patellofemoral complaints. Measurements of the articular cartilage congruence can be helpful to define an underlying pathology of patellar height, such as patella alta or infera.     

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.     

Proximal patellar tendinosis and abnormalities of patellar tracking

Objective. To assess whether an association exists between patellar tendinosis and abnormal patellar tracking. Design and patients. The MRI examinations of 630 patients (i.e. 860 knees) referred with anterior knee pain over a 4-year period were assessed in retrospect for the presence of patellar tendinosis and abnormal patellar tracking. The images of the patients with patellar tendinosis were reviewed and the location within the patellar tendon was recorded. Results. There were 44 knees with proximal patellar tendinosis. Twenty-four of these were considered to have normal patellar tracking and 20 to have abnormal patellar tracking. In the group of 816 knees without proximal patellar tendinosis, 581 were considered to have normal patellar tracking and 235 knees to have abnormal patellar tracking. When the two groups were compared there was a statistically significant difference in the ratio of patients with and without abnormal tracking. Conclusion. In patients referred with anterior knee pain or suspected abnormal patellar tracking there is a significant association between proximal patellar tendinosis and abnormal patellar tracking. Received: 3 June 1998 Revision requested: 4 August 1998; 16 November 1998 Revision received: 9 November 1998; 18 January 1999 Accepted: 29 January 1999     

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.     

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.     

镍钛形状记忆合金聚髌器治疗髌骨骨折42例

 目的观察镍钛形状记忆合金聚髌器这一新型髌骨骨折内固定方法的疗效.方法选取我院1995年～2002年就诊的髌骨骨折患者42例,均符合手术适应证,采用镍钛形状记忆合金聚髌器治疗.结果经术后随访,优良率达97.6%,骨折愈合率达100%,随诊未发现聚髌器断爪、松动、戳破皮肤、骨折移位、骨不连及关节面阶梯等现象.结论该方法固定可靠,使用安全,疗效确切,符合髌骨骨折内固定的生物力学要求,改善了髌骨骨折内固定技术.     

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.     

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.     

Quantification of patellar tracking using kinematic MRI

The purpose of this study was to describe a method to quantify dynamic patellar tracking using kinematic MRI (KMRI). Twelve normal females and three patients with patellofemoral pain participated. Imaging was performed with a 1.5-T/64-MHz MR system using a fast spoiled gradient-recalled acquisition in the steady state (GRASS) pulse sequence. A nonferromagnetic positioning device permitted active, bilateral knee extension against resistance (15% bwt) from 45° knee flexion to full extension. Subjects were instructed to extend their knees at a rate of 9° per second, which allowed images to be obtained at 45°, 36°, 27°, 18°, 9°, and 0°. All images were assessed for medial/lateral patellar displacement, patellar tilt, and sulcus angle using a computer-aided system. Normal patellar motion was characterized by medial movement from 45° to 18°, followed by a reversal toward lateral displacement from 18° to full extension. The results for patellar tilt revealed a tendency toward decreasing lateral tilt as the knee extended. Sulcus angle measurements indicated that the patella was moving to a more shallow portion of the trochlear groove (superiorly) during extension.     

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.     

Bone-ligament interaction in patellar tendon reconstruction of the ACL

The bone-ligament junction is one of the most complex biological tissues. Its key function is distribution of mechanical loads applied to the ligament in such a way as to diminish the concentration of stresses or shearing at the interface. This paper reports an experimental assessment of the extent to which a nearly normal junction is formed following reconstruction of the anterior cruciate ligament (ACL) with patellar tendon in 20 New Zealand white rabbits sacrificed after 2–38 weeks. A histological comparison was also made with cadaver ACLs. After 5 weeks the new ligament was still separate from the tunnel wall, inflammation was no longer present, and there was no junction tissue. A thin fibrocartilage layer was observed between the bone and the ligament after 12 weeks and was thicker 6 weeks later. After 28 weeks, there was a substantial layer of fibrocartilage. The new junction was virtually physiological by the 38th week, with all four layers present. Many fibrocartilaginous cells were also visible between the collagen fibres. The bone-ligament insertion was almost normal. These findings indicate that tendon reconstruction results in the formation of a structure very similar to a physiological junction, and thus ensures better load distribution over a greater ligament insertion area.     

Measurement of the normal optic chiasm on coronal MR images.

PURPOSETo develop an objective method for measuring the optic chiasm and to document its normal range in size.METHODSMeasurements of the height and area of the optic chiasm, made on coronal T1-weighted MR images with the use of commercially available region-of-interest software, were obtained in 114 healthy subjects who had a total of 123 MR studies. A normal range and standard deviation were calculated, and the information was broken down by age and sex.RESULTSThe mean area of the optic chiasm was 43.7 mm2, with a standard deviation of 5.21. The mean width was 14.0 mm, with a standard deviation of 1.68.CONCLUSIONThe area and width of the optic chiasm can be measured with the use of commercially available software, which allows an objective estimate of the chiasm''s size. Knowledge of the normal size range of the optic chiasm can be helpful in the early detection of some disorders.     

Reliability and interobserver variability in radiological patellar height ratios

This study evaluated the reliability and interobserver variability of five patellar height ratios as measured by two examiners on standard radiographs: Insall-Salvati (IS), modified Insall-Salvati (MIS), Blackburne-Peel (BP), Caton-Deschamps (CD), and Labelle-Laurin (LL). Plain lateral radiographs with a knee flexion angle of 20° for IS, MIS, BP, and CD ratios and 90° for the LL method of 22 knees of 21 patients with varying pathological knee conditions were analyzed. Statistical results revealed a low interobserver variability with high correlation coefficients (0.86 for IS, 0.82 for MIS, 0.86 for BP, 0.92 for CD, and 0.81 for LL; P > 0.3) and low mean interobserver errors. However, regarding the reliability of the radiographic results of the different methods for patella alta, baja, or norma we found varying results in 68% of the patients. In two patients the patellar height was classified as alta, norma, or baja depending on the ratio used. Regarding the definitions of patellar height used by the authors of these methods, we found the lowest number of normal patellae with the IS ratio and no patella alta for the CD ratio. The LL method revealed the highest number of patella alta. The BP ratio showed intermediate results for both patella alta and baja, being the most moderate method. This study showed that there was a good interobserver reliability for the evaluation of patellar height according to the common radiological ratios. However, the high frequency of differing results between the different radiographic ratios showed that patellar height classification as “alta,”“norma,” or “baja” depends heavily on the chosen index. The differing results were due mainly to the normative patellar height data and to anatomical differences. Based on these findings we recommend a ratio using the articular surface of the patella in relation to the joint line. We recommend the BP method because it revealed the lowest interobserver variability and discriminated best among the groups alta, norma, and baja. Received: 6 December 1999 Accepted: 15 March 2000     

带血管蒂的自体骨髌腱骨重建前交叉韧带的临床研究

 目的观察"带与不带血管蒂的骨髌腱(PT)骨重建前交叉韧带(ACL)对早中期前交叉韧带完全断裂"的临床疗效.方法治疗组(A组)行带血管蒂骨髌腱骨重建前交叉韧带,对照组(B组)行不带血管蒂骨髌腱骨重建前交叉韧带.结果治疗组较对照组总有效率和显效率、前抽屉试验评分均高,两者间有显著性差异.结论带血管蒂骨髌腱骨重建前交叉韧带对治疗前交叉韧带损伤具有较好的治疗作用,可以明显缩短患者恢复时间,改善患者膝关节功能.     

Bilateral patellar tendon rupture in a child: a case report

Patellar tendon rupture in children is very rare. When it occurs, patellar tendon is usually ruptured either from the upper end as a sleeve fracture of the patella or from lower end as an avulsion fracture of the tibial tuberosity. In this report, we present the case of an otherwise healthy 9-years-old boy who had subsequent bilateral patellar tendon ruptures through the midparts, which has not been published previously in the literature. Treatment was performed with primary end-to-end repair, reinforcement with cerclage wires and fresh-frozen achilles tendon augmentation for both sides.     

Calcification of the patellar tendon after ACL reconstruction

Extensive calcification of the patellar tendon following ACL reconstruction with central-third bone–patellar tendon–bone autograft is a rarely seen complication. A 45-year-old male patient underwent combined intraarticular reconstruction of ACL with 1/3 central patellar bone–tendon–bone graft and extraarticular reconstruction with modified MacIntosh technique. Two cm of calcification of the patellar tendon was observed incidentally when he underwent a high tibial osteotomy due to medial compartment degeneration, secondary to varus malalignment, 18 months after the ACL surgery. The calcification, being painless, was left untouched during the surgery. At the final examination, 136 months postoperatively, the patient still had no complaint relating to the patellar tendon.     

Recurrent patellar dislocation after medial patellofemoral ligament reconstruction

We report on three cases of recurrent lateral patellar dislocation following a medial patellofemoral ligament (MPFL) reconstruction for patellar instability. In all three cases, an isolated MPFL reconstruction was performed with a double autogenous gracilis graft. The patellar fixation was done through bone tunnels. All three patients presented with a definite moderate to severe traumatic episode resulting in a recurrent patella dislocation and a transverse avulsion fracture at the medial rim of the patella. All three were treated by an open reduction and internal fixation with good results. No complication or recurrent dislocations occurred. We suggest that this complication is caused by the original underlying pathology such as dysplastic trochlea, abnormal TT–TG, patella alta and hyperlaxity, resulting a greater reliance upon the reconstructed MPFL for patellar stability. When subjected to a severe stress, the graft, which is stronger and stiffer than the original MPFL, will cause a fracture through the medial edge of the patella. This weak area results from the previous drill holes, which act as stress risers.     

Non-surgical treatment of patellar tendinopathy: A systematic review of randomized controlled trials

Study designSystematic review of randomized controlled trials.ObjectivesTo determine the most effective non-surgical treatment interventions for reducing pain and improving function for patients with patellar tendinopathy.MethodsStudies considered for this systematic review were from peer-reviewed journals published between January 2012 and September 2017. All included studies used a visual analogue scale (VAS) to evaluate the participant’s pain. The majority of the included studies also used the Victorian Institute of Sport Assessment Patellar Tendinopathy (VISA-P questionnaire) to assess participant’s symptoms and function.ResultsNine randomized controlled trials fit the inclusion criteria and were analyzed. The results of three studies supported the use of isometric exercise to reduce pain immediately. One study found patellar strapping and sports taping to be effective for reduction in pain during sport and immediately after. Eccentric exercise, Dry Needling (DN) (2 studies), injections with Platelet Rich Plasma (PRP), Autologous Blood Injection (ABI), and saline were found to have a more sustained effect on reducing pain and improving knee function.ConclusionIsometric exercise, patellar strapping, sports taping, eccentric exercise, injections with PRP, ABI, and saline and DN demonstrated a short-term pain relieving and functional improvement effect in subjects with patellar tendinopathy. Longer term follow up on interventions involving eccentric exercise, DN, and injections with PRP, ABI and saline showed sustained pain reduction and improvement in knee function.Level of evidenceLevel 1.     

The patellar tendinopathy in athletes: a sonographic grading correlated to prognosis and therapy

The purpose of this study is to determine in the athletes a sonographic grading of the patellar tendinopathy correlated to prognosis and therapy. The 298 patellar overuse tendinopathies were divided in four grades according to the extension of the injured area of the tendon in the axial sonograms. Grades 1, 2, and 3 were managed with medical and physical therapy. A surgical treatment was performed in grade 4 and in grades 1, 2, and 3 tendinopathies not responding to our conservative therapy. There were 21.8% injuries in grade 1 (100% responding; prognosis 20 days), 61.2% injuries in grade 2 (94.5% responding; prognosis 40 days), 16.4% injuries in grade 3 (85.7% responding; prognosis 90 days), and 0.6% injuries in grade 4. The sonographic study is fundamental to characterize adequately the patellar tendinopathy. The conservative therapy is the first option for grades 1, 2, and 3 as it determines a complete healing in most of cases.     

MRI evaluation of patellar tendon defect after harvesting its central third

Purpose: the purpose of this study was to evaluate defect width of patellar tendon after harvest for anterior cruciate ligament reconstruction. Materials and methods: we performed MRI at various time interval after graft harvest (2–96 months) on 28 patients who had had reconstruction of the anterior cruciate ligament using mid-third patellar tendon. T1 and T2 weighted axial images were obtained to assess donor site defect of the patellar tendon. Measurement of the defect width was performed at the level of menisci on the axial images. The patients were divided into two groups according to the time interval between operation and imaging. The defect width of patients with short time interval (2–12 months) was compared to the defect width of patients with long time interval (12–96 months). Results: the average defect width of patients with short time interval was 6.4 mm and it was 2.2 mm for the patients with long time interval. Decreased defect width was obtained from MRI images in the patients with long time interval. Closed donor site defect was detected in 1 out of 14 patients with short time interval and 6 out of 14 patients with long time interval. Discussion and conclusion: these results show that there is no complete closure of donor site defect up to 1 year. However, it seems to be nearly complete closure of patellar tendon defect in the long time period.