Extensor Mechanism Alignment Research Articles

Reliability and Validity of an Ultrasound-Derived Measure for Axial Patellofemoral Alignment

Background: Axial extensor mechanism alignment is routinely assessed in patients with patellofemoral instability.Although many of these assessments are described using magnetic resonance imaging, it is plausible that ultrasound (US) imaging could be utilized to provide similar information in a more cost-effective and time-efficient manner. Purpose: To (1) describe and assess the reliability of a novel measure of extensor mechanism alignment of the patellofemoral joint using musculoskeletal US and (2) establish the construct validity of this measure through comparison of patients with and without patellar instability. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: Patients with (n = 24; 14.2 ± 3.1 years; 83% female) and without (n = 26; 14.7 ± 2.8 years; 69% female) a clinical history of patellofemoral instability (PFI) participated. Extensor mechanism alignment was assessed bilaterally on US, measuring the distance between the midpoint of the patellar tendon to the lateral trochlear ridge (MPT-LTR). Interrater reliability of the measurements was assessed using the intraclass correlation coefficient (ICC), with a minimum of 1 week between measurements for test-retest reliability. Differences between limbs were assessed using paired-samples t tests, and between-group differences were compared using independent-samples t tests. Results: Patients with PFI demonstrated a significantly smaller MPT-LTR distance than healthy controls on both their involved (8.1 ± 3.6 vs 12.6 ± 2.6 mm) and uninvolved (8.9 ± 3.4 vs 12.9 ± 2.4 mm) limbs ( P < .001 for both), indicating greater lateralization of the patellar tendon relative to the trochlea. There were no differences found between limbs for either patients with PFI ( P = .26) or controls ( P = .46). Interrater reliability was good (ICC = 0.785; 95% confidence interval [CI], 0.579-0.890), and test-retest reliability (n = 8) was excellent (ICC = 0.958; 95% CI, 0.790-0.992). Conclusion: The US-based MPT-LTR distance demonstrated good-to-excellent reliability. When compared with controls, the MPT-LTR distance was smaller in patients with PFI, indicating greater lateralization of the extensor mechanism.

Patellar Tilt and Patellar Tendon–Trochlear Groove Angle Present the Optimum Magnetic Resonance Imaging Diagnostic Reliability for Patients With Patellar Instability

To describe, in controls and in a population with patellar instability, magnetic resonance imaging values of measurements representing major associated factors for patellar instability (patellar height, trochlear dysplasia, and extensor mechanism alignment), as well as their cutoff values. In total, 323 knee magnetic resonance imaging scans, 142 with patellar instability and 181 controls without patellofemoral complaints (anterior cruciate, medial collateral ligament, meniscus ruptures or normal) were evaluated. Means, normality values in the control population, ideal cutoff values through receiver operating characteristic curves analysis, and interobserver reliability (intraclass correlation coefficient) were described for a series of measurements. All measurements were statistically different in control and instability patients, except for the patellotrochlear index and tibial tuberosity to posterior cruciate ligament distance. The interobserver intraclass correlation coefficient was good or excellent (above 0.75) only for the patellotrochlear index, patellar tendon-trochlear groove (PTTG) angle, and patellar tilt. The optimal cutoff value for each measurement was: PTTG angle ≥25.3o with sensitivity (S) of 70% and specificity (E) of 89%, patellar tilt ≥16o (S: 69% and E: 84%), trochlear sulcus angle ≥153o (S: 75% and E: 76%), Carrillon ≤12.8o (S: 62% and E: 87%), PTTG distance ≥11mm (S: 71% and E:78%), Caton-Deschamps index ≥1.23 (S: 72% and E: 76%) and trochlear bump ≥3.95 mm (S: 76% and E: 65%). Caton-Deschamps index (≥1.23), trochlear sulcus angle (≥153o), ventral prominence of the trochlea (≥3.95 mm), PTTG distance (≥11 mm), PTTG angle (≥25.3o), Carrillon angle (≤12.8o), and patellar tilt (≥16o) presented better diagnostic performance for patellar instability. Patellotrochlear index and tibial tuberosity to posterior cruciate ligament distance were not related to patellar instability. The interobserver reliability of the factors related to patellar instability was excellent only for the PTTG angle and lateral patellar tilt. III, retrospective case-control study.

High tibial derotation osteotomy for distal extensor mechanism alignment in patients with squinting patella due to increased external tibial torsion

BackgroundThe patellofemoral joint is often affected by torsionaldisorders of the lower limb, causing pain, instability and knee degeneration. The aims of this study were to determine functional outcomes of patients who underwent a high tibial derotation osteotomy (HTDO) for symptomatic squinting patella due to increased external tibial torsion. Moreover, factors associated with inferior clinical outcomes were investigated. MethodsPatients with symptomatic squinting patella, increased external tibial torsion (>30°) treated with this technique, and with 2 years of follow up were included. Fulkerson and Kujala patellofemoral joint scores were assessed. Age, body mass index, history of prior surgery, increased femoral anteversion, association of lateral retinaculum release and patellar cartilage lesions were analysed. ResultsSixty HTDOs were included in this retrospective study with an average of 66 months of follow up. The mean Kujala score improved from 47.5 preoperatively to 93 postoperatively. The mean Fulkerson score improved from 40.6 to 91.6. Kujala subscores for pain improved from 8.6 to 30.4, for instability improved from 6.4 to 17.9, and their ability to climb stairs increased from 6.9 to 17.9 (all P < 0.0001). Multivariate logistic regression model identified that patient age (P < 0.005) and advanced chondral damage (P < 0.001) were the dominant factors predicting inferior clinical outcomes using Kujala’s score. ConclusionHTDO provided good results regarding the pain symptoms, instability and the ability to climb stairs. Advanced chondral damage and advanced age had negative effects on outcomes.

Is There a Relationship between Patellofemoral Alignment and Osgood-Schlatter Disease? A Case-Control Study.

This study was aimed to investigate the role of anatomic variations in patellofemoral alignment in patients with or without Osgood-Schlatter disease (OSD) and to determine the potential anatomic risk factors that may play role in the etiology. This prospective observational case-control study was conducted on two groups of adolescent patients. Group 1 comprised patients who were diagnosed as having OSD and group 2 consisted of an equal number of age-matched patients who presented to the outpatient clinic with traumatic knee injury and underwent knee radiographic examination but without a diagnosis of OSD. Age, height, weight, body mass index (BMI), dominant side, and level of sporting activity were recorded. Quadriceps (Q) angles were measured using a long-arm goniometer with patients lying in the supine position with their knees in full extension and contracting the Q muscles. On anteroposterior, lateral knee, and tangential patella (Merchant and Laurin views) radiographs, the following measurements were performed: Insall-Salvati (IS), Caton-Deschamps (CD), and Blackburne-Peel (BP) indexes, congruence angles, lateral patellofemoral angles, sulcus angles, and patella type according to Grelsamer's morphology classification. Both groups were similar in respect of age (p = 0.160), sex (p = 0.311), height (p = 0.326), weight (p = 0.596), BMI (p = 0.153), and dominancy (p = 0.500). The rate of patients engaged in sports activities was significantly greater in the OSD group (p = 0.003). No significant difference was determined between the groups in respect to IS index, CD index, BP index, sulcus angle, lateral patellofemoral angle, and congruence angle (p-values: 0.358, 0.995, 0.912, 0.802, 1.000, and 0.907, respectively). The mean Q angle was measured as 15.6 ± 2.2 degrees in the OSD group and 14.3 ± 2.5 degrees in the control group (p = 0.014). Despite the difference being statistically significant, it was clinically insignificant because the difference was only 1.3 degrees. The principle etiologic factor seems to be increased physical activity rather than subtle variations is patellofemoral anatomy and alignment of extensor mechanism.

Evaluation of the Tibial Tubercle to Posterior Cruciate Ligament Distance in a Pediatric Patient Population.

Evaluation of distal extensor mechanism alignment continues to evolve in children with patella instability. Prior studies support the use of the tibial tubercle to trochlear groove (TT-TG) distance but limitations exist for this measurement including: changes in the TT-TG distance with knee flexion, difficulty with finding the deepest part of a dysplastic trochlea, and limitations regarding identification of the site of the anatomic abnormality. The tibial tubercle-posterior cruciate ligament (TT-PCL) distance has been introduced as an alternative measure to address the shortcomings in the TT-TG distance by quantifying the position of the TT independent of the trochlea and with respect to the tibia only. The objectives of this study were to (1) confirm that TT-PCL measurements in the pediatric population are reliable and reproducible; (2) determine whether normal TT-PCL distance changes with age; and (3) compare TT-PCL distances in patients with and without patellar instability to assess its utility in the workup of pediatric patellar instability. All knee magnetic resonance imaging performed for patients from birth to 15.9 years of age at our institution between December 2004 and February 2012 were retrospectively collected (total 566). Eighty-two patients had patellar instability and 484 patients did not have patellar instability. Two magnetic resonance imaging reviewers measured TT-PCL distance on T2-weighted axial images in a blinded manner. Intraobserver and interobserver agreement was measured. Correlation between TT-PCL distance and age as well as group differences between mean TT-PCL distances was evaluated. Intraobserver and interobserver agreement was excellent (0.93) and very good (0.80), respectively. The mean TT-PCL distance was 20.1 mm with a range of 5.8 to 32.1 mm. The mean age was 12.6 years with a range of 0.8 to 15.9 years. The average TT-PCL distance was 21 mm for the instability group and 19.9 mm for the control group. TT-PCL distance increased significantly as subject age increased; however, there was no significant measurement difference shown between the patellar instability group and the control group. TT-PCL distance increased with age in the pediatric population but did not correlate with recurrent patella instability in this pediatric cohort. Level III-diagnostic.

Lateral patellar retinacular release: changes over the last ten years

Lateral retinacular release is a useful resource in knee surgery that can be used for disorders of the extensor mechanism. For many years, it was indiscriminately used in the treatment of the various patellofemoral joint alterations, with conflicting functional results. This study aimed to analyze the changes that have occurred in the indications and clinical effectiveness of lateral retinacular release by reviewing the relevant literature of the past ten years, comparing it to the classic literature on the subject. It was found that less extensive releases decompress the lateral patellar facet, helping with pain control, while decreasing the risks of medial subluxation. Nowadays, there is clear evidence for its indication in the lateral patellar hypercompression syndrome associated with anterior knee pain, as long as there is no related instability; furthermore, it will normally play an adjuvant role in extensor mechanism alignment surgeries for cases of recurrent patellar instability. The initial results for symptomatic patellofemoral osteoarthritis are promising when lateral release is combined with cartilage debridement; in total knee replacement, it is more commonly used for the correction of valgus deformity in order to improve the components’ congruency. Finally, distinguishing the different patellofemoral joint pathologies is seen as crucial in order to indicate this procedure. Further randomized control trials that compare surgical techniques with long-term results are still needed.

Liberação retinacular lateral da patela: o que mudou nos últimos dez anos

Lateral retinacular release is a useful resource in knee surgery that can be used for disorders of the extensor mechanism. For many years, it was indiscriminately used in the treatment of the various patellofemoral joint alterations, with conflicting functional results. This study aimed to analyze the changes that have occurred in the indications and clinical effectiveness of lateral retinacular release by reviewing the relevant literature of the past ten years, comparing it to the classic literature on the subject. It was found that less extensive releases decompress the lateral patellar facet, helping with pain control, while decreasing the risks of medial subluxation. Nowadays, there is clear evidence for its indication in the lateral patellar hypercompression syndrome associated with anterior knee pain, as long as there is no related instability; furthermore, it will normally play an adjuvant role in extensor mechanism alignment surgeries for cases of recurrent patellar instability. The initial results for symptomatic patellofemoral osteoarthritis are promising when lateral release is combined with cartilage debridement; in total knee replacement, it is more commonly used for the correction of valgus deformity in order to improve the components’ congruency. Finally, distinguishing the different patellofemoral joint pathologies is seen as crucial in order to indicate this procedure. Further randomized control trials that compare surgical techniques with long‐term results are still needed.

Ultrasound Diagnosis for Preventing Knee Injuries in Cuban High-Performance Athletes

Diagnostic evaluation of the musculoskeletal system has traditionally been based on medical history, physical examination, and x-rays (techniques that provide limited information), and more re- cently on computerized axial tomography and magnetic resonance imaging (both very expensive). Ultrasound, a non-invasive and less expensive method, has become an indispensable tool for diagnos- ing overuse sports injuries. The Imaging Department at the Cuban Sports Medicine Institute (abbreviated in Spanish as IMD) developed a preventive ultrasound diagnostic imaging method and has applied it for the last 15 years as part of the IMD's medical management of high-performance athletes. Objectives Identify normal ultrasound patterns for knee structures and extensor mechanism alignment, and perform ultrasound imag- ing of the knee on asymptomatic, high-performance athletes to detect alterations and endogenous predisposing factors to overuse sports injuries as a basis for adopting preventive action. Methods A descriptive cross-sectional study was conducted of 300 non-athletes (control) and 100 Cuban Olympic athletes (preselected for the 2000 Olympic Games in Sydney, Australia). The IMD's Preven- tive Ultrasound Diagnostic Imaging Method was used to perform static and dynamic ultrasound examinations of both knees of all subjects (800 knees total) to determine normal patterns, detect structural alter- ations in the knee, and determine extensor mechanism malalignment. For the latter, Anillo's Patellofemoral Congruence Ultrasound Method was applied to determine the degree of patellar lateralization (RAB angle). Data was processed using descriptive statistics. To compare the ratio of ultrasound knee alterations detected, the Chi-square test was used. Percentiles were calculated based on data from the 600 non-athlete knees and were processed using the SPSS statistics ap- plication. Results Of the 100 athletes studied, 57 were found to have subclinical alterations in one or both knees, distributed as follows: synovitis (30), extensor mechanism malalignment (26), infrapatellar fat pad distortion (15), meniscal echostructure modification (14), ligament echostructure alteration (11), and articular cartilage alteration (7). Analysis of the control group findings established that RAB angle values greater than 13° for both sexes suggest excessive patellar lateralization with respect to the axial axis of the femur, potentially an endogenous risk factor favoring injury. Conclusions Preventive ultrasound diagnostic imaging of the knee, performed using IMD's ultrasound scanning methodology and incorpo- rating the normal ultrasound patterns described in this study, enables diagnosis of distortions in the articular and periarticular echostructure prior to the onset of clinical symptoms, as well as observation of en- dogenous predisposing factors linked to overuse sports injuries. As a result, appropriate measures can be adopted to prevent such injuries and to tailor medical management of high-performance athletes.

Fulkerson Procedure for Chronic Patella Component Dislocation After Total Knee Arthroplasty

Chronic patella component dislocation after primary knee arthroplasty can be a challenging problem. The purpose of this case series was to review our results of a chronic patella dislocation after total knee arthroplasty treated with a Fulkerson procedure (anteromedialization of the tibial tubercle). Five patients with an average age of 68.8 years (range, 60-76 years) underwent a Fulkerson procedure to restore extensor mechanism alignment. The tibial tubercle osteotomy was secured with lag screws with an average medialization of approximately 1.5 cm. The average preoperative Knee Society score was 70.5 points that improved to 85 points postoperatively. The average knee flexion was 93° preoperatively that improved to 101° postoperatively. Adequate patellofemoral alignment was achieved in all patients along with union of the tibial tubercle osteotomy site. The Fulkerson procedure appears to be an excellent treatment option in patients with a chronically dislocated patella component after total knee arthroplasty.

Joint Distraction and Reconstruction in Complex Knee Contractures

We retrospectively reviewed the results of joint distraction and reconstruction in complex knee contractures in 6 patients with 9 knees. The circular Ilizarov fixator was used in all cases. Extensor mechanism alignment with frame in situ was performed in 4 cases and alignment of mechanical axis of the lower limb was done in 2. All patients had a mean total arc of movement of 79 degrees before operation; however, this was nonfunctional because of the degree of flexion contracture. Three of the 6 patients were nonambulant before surgery. After joint distraction and reconstruction, mean total arc of movement remained unchanged, but this was more functional with improvement in the mobility status. At an average follow-up of 53 months, the mean flexion contracture was 100 degrees (range, 0-70 degrees), with further flexion possible up to 90 degrees (range, 60-120 degrees). Four patients had no recurrence. All 6 patients were ambulant with or without orthosis. Rebound phenomenon with loss of achieved correction was observed in 2 patients. Four patients were quite satisfied with results of surgery. Realignment of the extensor mechanism and mechanical axis is an important part that needs to be addressed in flexion contractures of the knee. Proper preoperative planning and staged procedures reduce the risk of recurrence. A treatment protocol is proposed to help in planning and further management.

Surgical correction of miserable malalignment syndrome.

Anterior knee pain is one of the more frustrating problems that orthopaedic surgeons treat. This study investigates the results of surgical correction of miserable malalignment syndrome associated with significant patellofemoral pain. The authors identified and retrospectively reviewed 14 consecutive patients with 27 limbs associated with excessive femoral anteversion, excessive tibial outward rotation, and patellofemoral pain. All of the patients were initially reviewed by the senior author and subsequently treated by ipsilateral outward femoral osteotomy and inward tibial osteotomy. All of the patients had failed nonoperative treatment. No persistent complications were seen. Subjectively and clinically, all of the patients were reviewed at an average of 5.2 (range 2.0-12) years after surgery. All of the patients reported full satisfaction with their surgery and outcomes. Most of the current literature discusses alignment in association with patellofemoral pain in the form of the extensor mechanism alignment. When evaluating patients with patellofemoral pain, it is imperative to assess the rotational profiles of the femur and tibia. The authors recommend that rotational osteotomies be performed in patients with patellofemoral pain and associated excessive femoral and tibial torsion, otherwise known as miserable malalignment syndrome.

The effect of patella taping on quadriceps strength and functional performance in normal subjects

Objective. To investigate the effect of patella taping on normal subjects. This was undertaken through the examination of isokinetic quadriceps strength and functional performance (hop distance), in an attempt to clarify the mechanism behind patella tapings reported success in the patellofemoral pain syndrome (PFPS) patient population. The aim of the study is to examine the effect of patella taping on normal quadriceps function. Method. Forty asymptomatic females (mean age 20.4±1.9 years) had their single hop for distance and concentric quadriceps peak torque (on an isokinetic dynamometer at 180°/s) assessed under two conditions (with or without patella taping) using a same subject randomised repeated measures design. Results. Patella taping brought about a significant decrease in hop distance ( p=0.004) and a non-significant decrease in quadriceps concentric peak torque ( p=0.47). Conclusion. Taping brought about a decrease in performance of normal subjects, this may be because of a subtle alteration in the extensor mechanism alignment causing it to function in less than optimal manner. This research supports the hypothesis that the mechanism by which patella taping has brought about reported improvements in PFPS patients is not solely related to a reduction in pain inhibition, but may involve an alteration in patella position and so efficient functioning of the extensor mechanism.