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Objective: To determine the correlation between patellar tendon-lateral femoral condyle friction syndrome (PLFFS) and the morphological characteristics of the antero-inferior part of the lateral femoral condyle (ALFC) to explore the potential pathogenesis., Methods: A total of 170 knees of 140 patients with PLFFS (PLFFS group) were retrospectively analyzed using magnetic resonance imaging (MRI) data for a 4-year period from our database. The Insall-Salvati ratio, shape of the ALFC (SALFC, defined as two subtypes: sharp versus blunt), lateral femoral condyle angle (LFCA), lateral trochlear length (LTL), and lateral trochlear height (LTH) were measured on MRI. Two groups were enrolled as controls: pure patella alta group (n = 192) and normal group (n = 172). All the parameters of the PLFFS group were compared with those of the two control groups., Results: The LFCA was significantly lower (p < 0.001) in the PLFFS group than in the pure patella alta group. The SALFC was significantly different (p < 0.001) in these two groups, whereas the Insall-Salvati ratio, LTH, and LTL showed no significant difference. The LFCA, LTH, SALFC, and the Insall-Salvati ratio in the PLFFS group were also significantly different (p < 0.001) with the normal group. Receiver operating characteristic (ROC) analysis showed the efficacy of the Insall-Salvati ratio and SALFC was better than that of the other parameters., Conclusions: The morphological characteristics of ALFC are correlated with PLFFS. The sharp shape of ALFC may be an important causative co-factor along with patella alta in the pathogenesis of PLFFS., Key Points: • A sharp margin of the antero-inferior lateral femoral condyle is an important risk factor for the development of PLFFS in patients with patella alta. • Antero-inferior femoral condyle shape can easily be assessed with high intra- and inter-reader reliability PLFFS. • PLFFS is more common in young adults.

Anatomical variants can be found throughout the whole body. Especially in the knee region, some variability has been reported concerning the osseous, tendinous, and muscular system. Beside a few cases of patellar tendon aplasia, no anatomical variations of this tendon are known. We present a rare case of a doubled patellar tendon as an anatomical variant, which to our knowledge, has not been described previously., Competing Interests: The authors declare that they have no conflict of interest.

Purpose: To translate the patellofemoral disorder questionnaire "Kujala Score" into Spanish and to adapt it for Spanish culture ., Methods: International recommendations were followed to translate the "Kujala Score" into Spanish together with a cultural adaptation and validation. We analysed the following parameters: internal consistency, agreement construct validity, test-retest reliability, ceiling and floor effects, and responsiveness. The reproducibility and responsiveness were tested in 72 patients with patellofemoral pain syndrome in a test-retest design with follow-up testing at 7 days. The "Kujala Score" and the VISA-P were administered to 98 patients and 30 patients, respectively, who completed the "Kujala Score" and VISA-P after physiotherapy treatment, which consisted of rest, ice, proprioceptive exercise and manual therapy., Results: The Spanish "Kujala Score" had high internal consistency (Cronbach α = 0.8; if an item was deleted, Cronbach α = 0.77-0.80), excellent reliability and agreement (interclass correlation coefficient = 0.99), and good construct validity that was significantly correlated with the outcome of the Spanish VISA-P (Spearman rho = 0.7; P < 0.001). No ceiling or floor effects was detected for the Spanish "Kujala Score" or the responsiveness of the participants based on 40 patients receiving physical therapy, rest, ice and proprioceptive exercises for 1 month, demonstrating that it is a good determinant of changes in the symptomatology of patients with knee pain., Conclusions: The Spanish adaptation of the patellofemoral disorder questionnaire "Kujala Score" proved to be valid and sensitive to clinical changes and to be a reliable instrument to assess the severity of pain and disability in patients with patellofemoral disorders. This questionnaire will be useful in clinical practice and research as an appropriate tool to evaluate and record the symptomatology of patients with patellofemoral pain syndrome among Spanish population., Level of Evidence: Diagnostic study, Level I.

Purpose: The purpose of this investigation was to estimate and document the reliability and validity of the Anterior Knee Pain Scale (AKPS) and to estimate its relative prediction accuracy of anterior knee pain in young females., Methods: Data from a prospective, epidemiologic study to diagnose patellofemoral knee pain among female athletes (n = 499) using the Anterior Knee Pain Scale (AKPS). Data were treated in 4 phases (descriptive phase, reliability phase, scale refinement phase) and a final validation stage that was focused on an effort to test and document the validation of the AKPS short form and perform head-to-head comparisons of the 6-item short form with the original, 13-item form., Results: The AKPS was reduced from 13 items (αCoeff = 0.77, σSEM = 0.004) to 6 items (αCoeff = 0.78, σSEM = 0.004). Point-biserial correlations with patellofemoral pain diagnosis were comparable: r [498] = 0.70 (R(2) = 0.49, short form) and r [498] = 0.71 (R(2) = 0.51, long form), as was sensitivity: 84% (short form) and 80% (long form), and specificity: 89% (short form) and 90% (long form; AUC = 0.94 both)., Conclusion: The current analyses indicate that a subset of measures from the AKPS is responsive to patellofemoral pain symptoms and may support screening for related diagnoses. A simpler and quicker scale optimized for diagnostic accuracy could reduce the demand on patients, clinicians and research teams focused on the identification and management of patellofemoral pain., Level of Evidence: III.

Purpose: The presence of anterior knee pain remains one of the major complaints following total knee arthroplasty (TKA). Since the introduction of the mobile TKA, many studies have been performed and only a few show a slight advantage for the mobile. In our short-term follow-up study, we found less anterior knee pain in the posterior stabilized mobile knees compared to the posterior stabilized knees. The concept of self-alignment and the results from our short-term study led us to form the hypothesis that the posterior stabilized mobile knee leads to a lower incidence of anterior knee pain compared to the posterior stabilized fixed knee. This study was designed to see whether this difference remains after 7.9 years in the follow-up. A secondary line of enquiry was to see whether one was superior to the other regarding pain, function, quality of life and survival., Methods: This current report is a 6-10-year (median 7.9 years) follow-up study of the remaining 69 patients with a cemented three-component TKA for osteoarthritis in a prospective, randomized, double-blinded clinical trial., Results: In the posterior stabilized group, five of the 40 knees (13%) versus five of the 29 posterior stabilized mobile group (17%) experienced anterior knee pain. No differences were observed with regard to ROM, VAS, Oxford 12-item knee questionnaire, SF-36, HSS patella, Kujala or the AKSS score. Patients with anterior knee pain reported more pain, lower levels of the AKSS, HSS patella and the Kujala scores than the patients without anterior knee pain., Conclusion: In the current clinical practice, the appearance of anterior knee pain persists as a problem; simply changing to a mobile bearing does not seem to be the solution. The posterior stabilized mobile total knee did not sustain the advantage of less anterior knee pain, compared with the posterior stabilized fixed total knee arthroplasty., Level of Evidence: Therapeutic study, Level II.

Purpose: Anterior knee pain is a major cause of complaint in total knee arthroplasty (TKA) without patellar resurfacing. The concept of improved patellar tracking and decreased retropatellar contact pressure for lateral retinacular release theoretically suggests that patients with lateral retinacular release in TKA would achieve a lower incidence of anterior knee pain when compared without lateral retinacular release. We sought to determine (1) whether those patients who received a routine lateral retinacular release in TKA would attain lower incidence of anterior knee pain as compared to patients who received TKA without lateral retinacular release and (2) whether lateral retinacular release would increase the lateral retinacular release-related complications., Methods: A total of 148 patients who underwent TKA with the use of the Gemini MK II mobile bearing were randomized to receive either routine lateral retinacular release (intervention group) or not (control group). Patients were assessed by the visual analogue scale for anterior knee pain, the Knee Society clinical scoring system of knee score and function score, and patellar score for clinical function. Patients' satisfaction and lateral retinacular release-related complications were also evaluated., Results: The overall incidence of anterior knee pain in the intervention group at 18 months follow-up was 5.6%, while that of the control group was 20.6% (p = 0.009). No statistical difference was detected between the two groups in terms of lateral retinacular release-related complications (n.s.), patients' satisfaction (n.s.), knee score (n.s.), function score (n.s.), and patellar score (n.s.) at 18 months follow-up., Conclusion: The present study suggests that routine lateral retinacular release can reduce anterior knee pain and does not increase lateral retinacular release-related complications, in TKA with the use of the Gemini MK II mobile bearing without patellar resurfacing., Level of Evidence: Therapeutic, Level I.

Purpose: Anterior knee pain (AKP) following total knee replacement (TKR) is both prevalent and clinically relevant. The purpose of this study was to systematically review the peer-reviewed literature, and to identify and assess the different modifiable and non-modifiable determinants that may be associated with the development of AKP in patients following primary TKR., Methods: A systematic computerized database search (Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and Google Scholar) was performed in January 2012. The quality of the studies was assessed using the GRADE approach., Results: A total of 54 articles met the inclusion criteria. Variables that have been researched with regard to the prevalence of AKP include patient and knee-specific characteristics, prosthetic design, operative technique, treatment of the patella, and time of assessment. A weak correlation with AKP was found for specific retained presurgery gait patterns. A weak recommendation can be given for the use of femoral components with a posterior centre of rotation, resection of Hoffa's fat pad, patellar rim electrocautery, and preventing combined component internal rotation. The correlation between postsurgical AKP and the degree of patellar cartilage wear, tibial component bearing strategies, and patellar resurfacing is inconclusive. Due to substantial heterogeneity of the included studies, no meta-analysis was performed., Conclusions: No single variable is likely to explain the differences in the reported rates of AKP, although variables leading to abnormal patellofemoral joint loading appear to be of special significance., Level of Evidence: III.

The quadriceps or Q-angle is an index of the vector for the combined pull of the extensor mechanisms and the patellar tendon. It is used as an indicator for patellofemoral joint dysfunction. The purpose of this article is to systematically review and appraise the literature to determine the reliability and validity of this test. An electronic database search was performed accessing AMED, British Nursing Index, CINAHL, the Cochrane database, EMBASE, ovid Medline, Physiotherapy Evidence Database (PEDro), PsycINFO, Pubmed and Zetoc to April 2008. All English language, human subject, clinical trials, assessing the inter- or intra-tester reliability, or the criterion validity, were included. The Critical Appraisal Skills Programme appraisal tool was used to establish the methodological quality of each study. Ten articles including 569 control and 179 patellofemoral disorder knees were reviewed. The findings suggest that there is considerable disagreement on the reliability and validity of the clinical Q-angle measurement. This may be due to a lack of standardisation in the measurement procedure. Further study is advocated to re-evaluate this topic using well-designed, and sufficiently large observational studies of specific patellofemoral dysfunction populations.

It may be very difficult to diagnose the pathology in patients with anterior knee pain. Patients with chronic anterior knee pain have been reviewed for the study. Our aim was to delineate the presence of subtle trochlear dysplasia by measuring lateral trochlear inclination (LTI) in axial magnetic resonance imaging (MRI) scans. While there were 109 knees in the study group with anterior knee pain (AKP), control group consisted of 74 knees without AKP. The LTI measurements were performed at the level of proximal cartilaginous area of trochlear groove in axial scans. The condition was termed to be trochlear dysplasia when LTI was below 11 masculine. Parameters in both groups were statistically analyzed and compared for their association with LTI. There was no significant difference between LTI values of male and female subjects in each group. The mean LTI values in anterior knee pain and control groups were 17.32 masculine and 21.5 masculine, respectively, and the difference was statistically significant (P < 0.05). The ratio of knees with trochlear dysplasia was 16.5% in AKP group, which was only 2.7% in control. In the AKP group, the ratio of trochlear dysplasia was significantly high (P < 0.05). Although trochlear dysplasia has been generally detected in cases with patellar instability, this study revealed that the frequency of this finding in patients with other causes of anterior knee pain was also considerably high. Measurement of lateral trochlear inclination in axial MRI scans with radiologic assessment seems to be a valuable diagnostic criterion, especially in patients in whom etiology of anterior knee pain could not be identified.

The most important causes of anterior knee pain include patellofemoral malalignment which causes patella-condyle contact anomalies at the patellofemoral joint, excessive patellar lateral pressure increase, trauma and overuse. In this article, besides presentation of late clinical results of 169 lateral retinacular release cases which were surgically treated between January 1995 and December 2002 with the help of a hook knife from the anterolateral portal due to lateral compression syndrome and patellar maltracking, we also described quadriceps tendon pressure-pull test which strongly indicates patellofemoral pain during physical examination of a patient with anterior knee pain. In addition to radiological patellofemoral imaging methods, we describe dynamic arthroscopic patellofemoral joint examination which is applied perarthroscopically to all of our surgically treated patients. We divided the patients into two groups: group 1 was the younger group with age 16-40 years; group 2 was the older group with age >41 years. Preoperative mean Lysholm scores for group I was 67.6 and 98.6, postoperatively, whereas it was 62.3 preoperatively and 91.4 postoperatively in group 2. This improvement of Lysholm scores postoperatively was statistically significant for each of the two groups (p=0.001). For group 1 preoperative IKDC scores were A in 8 patients, B in 61 patients and C in 11 patients, whereas it was A in 78 patients and B in 2 patients postoperatively. For group 2 preoperative IKDC scores were A in 2 patients, B in 43 patients, C in 36 patients and D in 8 patients, whereas it was A in 78 patients and B in 11 patients. This improvement of IKDC scores postoperatively was also statistically significant for each of the two groups (p=0.001). Preoperative and postoperative congruent angles of all patients were also measured. Preoperative mean congruent angle was +16.4 in group 1 while mean congruent angle was -7.1 postoperatively. For group 2 preoperative mean congruent angle was +18.7 preoperatively and -6.9 postoperatively. This improvement was statistically significant for each of the two groups (p=0.001). The overall number of patellar lateral compression syndrome cases were 51 (24 in group 1, 27 in group 2), patellar lateralization cases were 64 (28 in group 1, 36 in group 2) and patellar subluxation cases were 54 (28 in group 1, 26 in group 2). At the evaluation of arthroscopic lateral patellar facet and lateral femoral condylar chondral pathologies, we statistically showed that patellar chondral pathologies were more severe than the femoral chondral pathologies (p=0.001). In our opinion, the severity of patellar lateral facet chondral lesions, although it has a thicker layer of cartilage, is due to distribution of load to a larger contact area of lateral femoral condyle. Statistically increasing severity of femoral (Kendall's tau-b: 0.248, p=0.001) and patellar chondral lesions (Kendall's tau-b: 0.444, p=0.0001) with age is compatible with our arthroscopic and clinical observations. The most important complication seen in our cases was fibrosis at the site of lateral release, seen in three patients. They were healed without any sequela with local corticosteroid injection into the fibrosis tissue. We did not see any hemarthrosis or haematoma as a complication.

The patellofemoral pain syndrome (PFPS) remains a challenging musculoskeletal entity encountered by clinicians. Reviewing the literature, conflicting data seem to exist regarding the effect of non-operative treatment in PFPS patients. A possible explanation may be lack of a clear classification system of patients with PFPS. It is our opinion that the term PFPS still is a 'wastebasket', which probably comprises several different entities. Therefore, it seems important to subdivide this broad group of patients into different categories with a specific rehabilitation approach. In this study, we introduce a classification system, which reflects a consensus reached by the European Rehabilitation Panel. This classification system should help the clinicians to identify the cause(s) of patellofemoral pain, and consequently help to select the most appropriate non-operative treatment. The authors are aware that no rehabilitation protocol will work for all PFPS patients, since the underlying mosaic of pathophysiology and tissue-healing responses are unique. Therefore, the aim of this study with a classification system was to guide the clinician through clinical examination in order to develop a non-operative treatment protocol, specific for each individual with PFPS.