Patellar tendinitis (jumper's knee)

Current Concepts in Patellar Tendinopathy: An Overview of Imaging, Pathogenesis, and Nonoperative and Operative Management

» Approximately 1 in 3 high-impact athletes develops patellar tendinopathy (PT), with the proximal insertion of the patellar tendon being the most commonly affected anatomical site.» Nonoperative treatment options are effective in reducing pain and restoring functionality in most patients with PT. However, operative intervention should be considered when conservative management fails.» A comprehensive review of the literature on surgical procedures, including both open and arthroscopic approaches, was conducted with a specific focus on clinical outcomes and return to sports.» Both open surgery and arthroscopic surgery for PT have demonstrated favorable success rates and return-to-sport outcomes, with arthroscopic treatment potentially expediting the recovery process.

Bibliometric Analysis of the Top 50 Most Influential Studies on Patellar Tendon Injury

Background

There is a wide range of literature on patellar tendon injury, making it increasingly difficult to stay informed on the most influential studies in this field. It is essential to be familiar with the foundational articles of patellar tendon injury research to understand the current state of the literature and deliver high quality care.

Purpose

To objectively identify the 50 most influential articles relating to patellar tendon injury and conduct a bibliometric analysis to identify key features of these articles.

Study Design

Cross-sectional study.

Methods

The Clarivate Analytics Web of Knowledge database was utilized to gather metrics on the 50 most cited articles on patellar tendon injury on June 27, 2022. The information extracted from each article included publication year, number of citations, author information, article type, level of evidence, country of origin, journal name, study focus, and industry influence.

Results

The top 50 studies were cited a total of 8543 times and published between 1977 and 2015. The majority of articles were published after 2003, and the majority of citations were accrued after 2011. The most prevalent article types were cohort studies (n = 23), and the majority of studies were of evidence level 2 (n = 14) or 4 (n = 13). Australia and the United States (US) each published the most studies (n = 11). Only 4 (8%) studies focused on patellar tendon rupture, and 12 (24%) of the top 50 studies were associated with industry.

Conclusion

The majority of the top 50 most influential articles in patellar tendon injury were published and accumulated citations in the past 10 to 20 years. Non-US countries, institutions, and journals published many of the top 50 studies, reflecting a global interest and commitment to research in this field. Patellar tendon rupture and surgical repair represents a minority of research in the top 50 studies and could be a point of growth in the future.

MRI Characteristics and Alterations in Patellar Height in Patients with Patellar Tendinopathy-A Retrospective Study

(1) Background: Patellar tendinopathy (PT) is an overuse condition of the knee extensor mechanism characterized by ventral knee pain at the lower pole of the patella and limited functionality. (2) Methods: In this retrospective study, a group of patients with PT (n = 41) was compared with a control group (n = 50) in terms of patient-related data and magnetic resonance imaging (MRI) characteristics. (3) Results: Patellar height was higher in the PT patient group and there was a significant difference in Caton-Deschamps index (CD) compared to the control group (p = 0.021). Patients with PT showed a lower patella-patellar tendon angle (PPTA) (p = 0.011). The patellar tendon thickness (PTT) in the proximal (PTTprox), middle (PTTmid) and distal (PTTdistal) part of the tendon was significantly thickened (p < 0.001). Increased signal intensity in MRI was detected in symptomatic tendons over 6 months compared to a duration of less than 6 months (p = 0.025). A significant relationship between the PTTprox and an increased signal intensity was observed (p < 0.001). (4) Conclusions: Patients with PT showed a significant difference in the patellar height and PPTA. With persistence of symptoms over 6 months, MRI seems suitable to detect the morphologic tendon changes and further identify patients suitable for surgical procedures.

Cross-cultural adaptation, validity, reliability and responsiveness of the Japanese version of the Victorian Institute of sports assessment for patellar tendinopathy (VISA-P-J)

BACKGROUND

This study aimed to translate, adapt, and test the psychometric properties of the Japanese version of the Victorian Institute of sports assessment for patellar tendinopathy (VISA-P-J).

METHODS

This prospective cohort study registered 43 participants ≥ 18 years old with a history of painful symptoms in the inferior pole of the patella to the proximal patellar tendon lasting ≥ 1 month for patellar tendinopathy. Pain in daily life and during sports activities, symptom classification, and patient global impression of change were assessed at the baseline, 1 week, and 12 weeks. The psychometric properties, test-retest reliability, standard error of measurement, internal consistency criterion validity, construct validity, responsiveness, and interpretability, of the VISA-P-J were calculated according to the COSMIN.

RESULTS

The two-way random-effects, absolute agreement intraclass correlation coefficient for test-retest reliability of VISA-P-J was 0.87 (95% confidence interval: 0.78, 0.93), and the standard error of measurement of VISA-P-J was 0.89. The Cronbach's alpha for internal consistency of VISA-P-J was 0.81. A correlation between VISA-P-J and Roel's classification, Visual Analog Scale for pain (VAS)-Active Daily Living, and VAS-Sports (r = - 0.52, r = - 0.66, r = - 0.86, p < 0.01, respectively) was observed for criterion validity. All hypotheses of the hypothesis-testing method to evaluate construct validity and responsiveness of VISA-P-J were substantiated. The minimal clinically important difference of VISA-P-J was 7 points.

CONCLUSION

We demonstrated that the VISA-P-J was a reliable, valid, and responsive assessment method for individuals with chronic pain in the patellar tendon.

A Two-stream Convolutional Network for Musculoskeletal and Neurological Disorders Prediction

Musculoskeletal and neurological disorders are the most common causes of walking problems among older people, and they often lead to diminished quality of life. Analyzing walking motion data manually requires trained professionals and the evaluations may not always be objective. To facilitate early diagnosis, recent deep learning-based methods have shown promising results for automated analysis, which can discover patterns that have not been found in traditional machine learning methods. We observe that existing work mostly applies deep learning on individual joint features such as the time series of joint positions. Due to the challenge of discovering inter-joint features such as the distance between feet (i.e. the stride width) from generally smaller-scale medical datasets, these methods usually perform sub-optimally. As a result, we propose a solution that explicitly takes both individual joint features and inter-joint features as input, relieving the system from the need of discovering more complicated features from small data. Due to the distinctive nature of the two types of features, we introduce a two-stream framework, with one stream learning from the time series of joint position and the other from the time series of relative joint displacement. We further develop a mid-layer fusion module to combine the discovered patterns in these two streams for diagnosis, which results in a complementary representation of the data for better prediction performance. We validate our system with a benchmark dataset of 3D skeleton motion that involves 45 patients with musculoskeletal and neurological disorders, and achieve a prediction accuracy of 95.56%, outperforming state-of-the-art methods.

Surgical Management of Patellar Tendinopathy Results in Improved Outcomes and High Rates of Return to Sport: A Systematic Review

Although the majority of patients with patellar tendinopathy (PT) can be treated nonoperatively, operative management may be indicated for recalcitrant cases. While several surgical techniques have been described, there is limited understanding of postoperative outcomes and expectations regarding return to activity and sport. The purpose of this study was to characterize the clinical outcomes associated with the surgical management of PT with an emphasis on return to sport (RTS) rates. We hypothesized that surgical management would lead to clinically important improvements in patient-reported outcomes (PROs) with high rates of RTS and RTS at the same level. A comprehensive search of the PubMed, Medline, and Embase databases was performed in December 2020. Level of evidence studies I through IV, investigating results of surgical management for PT (PRO, functional outcomes, pain, and/or RTS), were included. The search was performed in accordance with the Preferred Reported Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Forty clinical studies reporting on surgery for PT satisfied inclusion criteria, with 1,238 total knees undergoing surgery for PT. A comparison of pre- and postoperative Victorian Institute of Sport Assessment, patellar tendon (VISA-P) scores (mean difference: 41.89, p < 0.00001), Lysholm scores (mean difference: 41.52, p < 0.00001), and visual analogue scale (VAS) pain scores (mean difference: 5, p < 0.00001) demonstrated clinically and statistically significant improvements after surgery. The overall RTS rate following operative management was 89.8% (95% confidence interval [CI]: 86.4-92.8, I ² = 56.5%) with 76.1% (95% CI: 69.7.5-81.9, I ² = 76.4%) of athletes returning to the same level of activity. Surgery for PT provides meaningful improvement in patient reported outcomes and pain while allowing athletes to RTS at high rates with levels of participation similar to that of preinjury. Comparative studies of open and/or arthroscopic surgery are still limited but current evidence suggests better rates of RTS for arthroscopic surgery compared with open surgery. This is a systematic review of level-I to -IV studies.

Knee dynamics during take-off and landing in spike jumps performed by volleyball players with patellar tendinopathy

[Purpose] Patellar tendinopathy is a common sports injury. The risk factors for this injury can be categorized as intrinsic, extrinsic, and dynamic. We examined the dynamic factors in this study. [Participants and Methods] The participants were volleyball players who were assigned to a patient group (n=6) if they had medial patellar tendinopathy in the left knee or to a control group (n=7) otherwise. The participants performed spike jumps, and their ground reaction force and three-dimensional kinematic data were recorded. Knee angle and moment data were extracted at the peak extension moment of take-off and landing. [Results] The two groups showed no differences in knee angles. A tendency for abduction/external rotation moments at take-off and landing on both sides was observed in the control group, while the patient group showed adduction and internal rotation moments at take-off and adduction moment at landing in the left (injured) knee. [Conclusion] The observed knee joint moments in the left (injured) knee of the patient group may have been involved in the pathophysiological mechanism underlying the development of patellar tendinopathy.

An Objective Measure of Patellar Tendon Thickness Based on Ultrasonography and MRI in University Athletes

Ultrasonography and MRI are used for imaging evaluation of patellar tendinopathy, and “thickening of the tendon” is known as one of the characteristic findings. However, there are no evidence-based quantitative criteria to help evaluate this phenomenon. The purpose of this study was to investigate an objective measure of patellar tendon thickness. Patellar tendon thickness was evaluated in 65 elite university athletes using both ultrasonography and MRI. The relationship between tendon thickness and clinical patellar tendinopathy was investigated, and the cutoff value of the tendon thickness was calculated. Of the 129 knees included in the analysis, clinical patellar tendinopathy was found in 16 knees (12.4%). The proximal patellar tendon was significantly thicker in athletes with clinical patellar tendinopathy on both ultrasonography (8.3 mm vs. 5.1 mm; p < 0.001) and MRI (9.9 mm vs. 5.5 mm; p < 0.001). Setting the cutoff value to a thickness of >7.0 mm was an accurate predictor of clinical patellar tendinopathy (ultrasonography: sensitivity 81.3%, specificity 95.6%; MRI: sensitivity 100%, specificity 89.4%). Both ultrasonography and MRI measurement of the proximal patellar tendon thickness reflected the presence of clinical patellar tendinopathy. Defining “thickening of the patellar tendon” as thicker than 7.0 mm on both ultrasonography and MRI therefore has clinical significance.

Sagittal patellar flexion angle measurement determines greater incidence of patella alta in patellar tendinopathy patients

PURPOSE

The objective of this study was to compare patellar height and patella alta between a control cohort and patients with patellar tendinopathy by the sagittal patellar flexion angle (SPFA) measurement.

METHODS

Magnetic resonance imaging (MRI) scans of the knee were obtained from a sports imaging facility and screened to select patients with anterior knee pain. This symptomatic group was divided into two patient cohorts: those with and without MRI features of patellar tendinopathy. Lateral knee radiographs were reviewed and SPFA, knee flexion angle and Insall-Salvati ratio (IS) were measured from the radiographs by two independent reviewers.

RESULTS

A total of 99 patients consisting of 48 patellar tendinopathy patients and 51 control patients were included. There was a significantly higher mean patellar height (p = 0.002, d = 0.639) and a greater patella alta incidence in the patellar tendinopathy cohort (25.0%) compared to the controls (3.9%) (p = 0.022, d = 0.312). Insall-Salvati ratio measurements showed no difference in patella alta incidence between tendinopathy and control cohorts. There was excellent inter- and intra-observer reliability of SPFA measurements (ICC 0.99).

CONCLUSION

This is the first study to demonstrate a greater incidence of patella alta in patellar tendinopathy patients compared to controls. A greater patella alta incidence amongst patellar tendinopathy patients as defined by SPFA was found to be clinically relevant, as it suggests these patients may comprise the recalcitrant patient subgroup who do not improve with current surgical intervention and may therefore benefit from a biomechanical surgical solution.

LEVEL OF EVIDENCE

III.

Patellar mobility and lower limb kinematics during functional activities in individuals with and without patellar tendinopathy

STUDY DESIGN

Case-control.

OBJECTIVE

To examine whether patients with patellar tendinopathy (PT) display greater patellar mobility and different lower body kinematics than patients without PT.

BACKGROUND

PT is a common overuse condition of the patellar tendon that can cause pain and impair function. Subjects with overuse knee problems display different hip and knee functional mechanics, specifically valgus collapse. Patellar hypermobility has not been specifically studied as a possible risk factor for PT.

METHODS

11 patients with PT and 11 controls without PT, age 18 to 40, were studied. Using a patellofemoral arthrometer (PFA), maximal lateral and medial patellar displacement was measured. 3-D motion analysis was performed to determine lower extremity joint motions during single-leg step down and drop vertical jump tests.

RESULTS

Patients with PT had significantly increased lateral patellar mobility compared to controls (12.21 ± 3.33 mm vs. 9.19 ± 1.92 mm, P = .017). PT patients showed significantly greater peak hip adduction with both drop vertical jump (2.7° ± 6.3° vs. -5.6° ± 4.2°; P = .003) and step down (17.0° ± 3.8° vs. 12.5° ± 4.4°, P = .024). PT patients demonstrated increased peak ankle external rotation with drop vertical jump (-21.1° ± 5.9° vs. -14.8° ± 5.5°, P = .023) and step down (-15.6° ± 5.5° vs. -9.0° ± 6.0°, P = .017).

CONCLUSIONS

Patients with PT exhibit increased lateral patellar mobility, hip adduction, and ankle external rotation. The effects of increased patellar mobility deserve further study in the development, management, and prevention of PT.

A biomechanical analysis of 3D stress and strain patterns in patellar tendon during knee flexion

Patellar tendinopathy is among the most widespread patellar tendon diseases in athletes that participate in activities involving running and jumping. Although their symptoms can be detected, especially at the inferior pole of the patella, their biomechanical cause remains unknown. In this study, a three-dimensional finite element model of knee complex was developed to investigate principal stress and strain distributions in the patellar tendon during 0° to 90° knee flexion and slow and fast level-ground walking. Results indicate that the patellar tendon is subjected to tensile stress and strains during all three activities. During flexion, its central proximal posterior region exhibited highest peak stress and strain, followed by central distal posterior, central distal anterior and central proximal anterior region. Similar trends and magnitudes were reported during slow and fast walking. The region with highest principal stresses and strains, central proximal anterior region, also corresponds to the most commonly reported patellar tendinopathy lesion site, suggesting that principal stress and strain are good indicators of lesion site location. Additional factors such as regional variations in material properties and frequency and duration of cyclic loading also need to be considered when determining the biomechanical aetiology of patellar tendinopathy.

High-energy dose of therapeutic ultrasound in the treatment of patellar tendinopathy: protocol of a randomized placebo-controlled clinical trial

BACKGROUND

Patellar tendinopathy is an extremely debilitating condition and its treatment usually requires a combination of clinical approaches. Therapeutic ultrasound (TUS) is one of the most available electrophysical agent in rehabilitation settings; however, there is also a lack of high-quality studies that test different dosimetric aspects of TUS. Thus, the purpose of this study is to evaluate the short-, medium-, and long-term effects of the combination of high-energy TUS with a rehabilitation program for patellar tendinopathy.

METHODS

This will be a randomized, placebo-controlled trial with blinding of patients, assessors, and therapist. The setting is an outpatient physical therapy clinic. We will recruit 66 participants (male and female) aged between 18 and 40 years and presenting with patellar tendinopathy. A treatment combining high-energy dose TUS and a rehabilitation program for patellar tendinopathy will be delivered twice a week for 8 weeks. The control group will receive the same treatment, but with a placebo TUS. The effectiveness of the intervention will be measured at the beginning (baseline), midpoint (4 weeks), and end of treatment (8 weeks), as well as at 3- and 6-months post-treatment. Primary outcomes will be pain intensity (visual analogue scale, VAS), and VISA-P questionnaire and primary time points will be baseline (T0) and the end of the program (T2). Also, IPAQ-short form questionnaire, muscle strength (manual dynamometry), 2D kinematics, pain pressure threshold (PPT) algometry, thermography, and magnetic resonance imaging (MRI) will be collected.

DISCUSSION

TUS will be applied in an attempt to enhance the results obtained with the rehabilitation program proposed in this study, as well as stimulate some repair responses in individuals undergoing treatment for patellar tendinopathy, which in turn may optimize and improve treatment programs for patellar tendinopathy as well as to establish new guidelines for the application of TUS.

TRIAL REGISTRATION

This study was prospectively registered at April-3rd-2018 and updated at September-1st-2019 in the Brazilian Registry of Clinical Trials (REBEC) under the registration number: RBR-658n6w.

Surgical Technique for Chronic Proximal Patellar Tendinopathy (Jumper's Knee)

Chronic proximal patellar tendinopathy is a challenging condition for its troublesome management in the active patient and difficulty in defining the failure of conservative treatment to indicate surgery. Usually, patients with chronic proximal patellar tendinopathy have already tried several physiotherapeutic modalities and are away from their preferred physical activities for variable periods. The current literature presents some open and even arthroscopic options for treating recalcitrant patellar tendinopathy using a variable magnitude of resources and costs. The purpose of this article was to depict a very simple and inexpensive surgical option for treating this condition, which can be applied worldwide.

Surgery for patellar tendinopathy (jumper's knee)

BACKGROUND

Patellar tendinopathy is an overuse condition that commonly affects athletes. Surgery is usually offered if medical and physical therapies fail to treat it effectively. There is variation in the type of surgery performed for the condition.

OBJECTIVES

To assess the benefits and harms of surgery for patellar tendinopathy in adults.

SEARCH METHODS

We searched the following databases, to 17 July 2018: the Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Library, OVID MEDLINE, OVID Embase, clinical trial registries (www.ClinicalTrials.gov) and the WHO trials portal (www.who.int/ictrp/en/).

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that compared surgical techniques (open or arthroscopic) with non-operative treatment (including placebo surgery, exercise or other non-surgical modalities) in adults with patellar tendinopathy.Major outcomes assessed were knee pain, function, quality of life, participant global assessment of success, withdrawal rate, proportion with adverse events and proportion with tendon rupture.

DATA COLLECTION AND ANALYSIS

Two review authors selected studies for inclusion, extracted trial characteristics and outcome data, assessed the risk of bias and assessed the quality of the evidence using GRADE.

MAIN RESULTS

Two trials (92 participants) met our inclusion criteria. Participants in both trials were followed for 12 months. Neither trial compared surgery to placebo surgery. One trial (40 randomised participants) compared open surgical excision with eccentric exercises, and the other compared arthroscopic surgery with sclerosing injections (52 randomised participants). Due to the nature of the interventions, neither the participants or the investigators were blinded to the group allocation, resulting in the potential for performance and detection bias. Some outcomes were selectively not recorded, leading to reporting bias. Overall, the certainty of the evidence from these studies was low for all outcomes due to the potential for bias, and imprecision due to small sample sizes.Compared with eccentric exercises, low-certainty evidence indicates that open surgical excision provides no clinically important benefits with respect to knee pain, function or global assessment of success. At 12 months, mean knee pain - measured by pain with standing jump on a 10-point scale (lower scores indicating less pain) - was 1.7 points (standard deviation (SD) 1.6) in the eccentric training group and 1.3 (SD 0.8) in the surgical group (one trial, 40 participants). This equates to an absolute pain reduction of 4% (ranging from 4% worse to 12% better, the minimal clinically important difference being 15%) and a relative reduction in pain of 10% better (ranging from 30% better to 10% worse) in the treatment group. At 12 months, function on the zero- to 100-point Victorian Institute of Sport Assessment (VISA) scale was 65.7 (SD 23.8) in the eccentric training group and 72.9 (SD 11.7) in the surgical group (one trial, 40 participants). This equates to an absolute change of 7% better function (ranging from 4% worse to 19% better) and relative change of 25% better (ranging from 15% worse to 65% better, the minimal clinically important difference being 13%). Participant global assessment of success was measured by the number of people with no pain at 12 months: 7/20 participants in the eccentric training group reported no pain, compared with 5/20 in the open surgical group (risk ratio (RR) 0.71 (95% CI 0.27 to 1.88); one trial, 40 participants). There were no withdrawals, but five out of 20 people from the eccentric exercise group crossed over to open surgical excision. Quality of life, adverse events and tendon ruptures were not measured.Compared with sclerosing injection, low-certainty evidence indicates that arthroscopic surgery may provide a reduction in pain and improvement in participant global assessment of success, however further studies are likely to change these results. At 12 months, mean pain with activities, measured on a 100-point scale (lower scores indicating less pain), was 41.1 (SD 28.5) in the sclerosing injection group and 12.8 (SD 19.3) in the arthroscopic surgery group (one trial, 52 participants). This equates to an absolute pain reduction of 28% better (ranging from 15% to 42% better, the minimal clinically important difference being 15%), and a relative change of 41% better (ranging from 21% to 61% better). At 12 months, the mean participant global assessment of success, measured by satisfaction on a 100-point scale (scale zero to 100, higher scores indicating greater satisfaction), was 52.9 (SD 32.6) in the sclerosing injection group and 86.8 (SD 20.8) in the arthroscopic surgery group (one trial, 52 participants). This equates to an absolute improvement of 34% (ranging from 19% to 49%). In both groups, one participant (4%) withdrew from the study. Functional outcome scores, including the VISA score, were not reported. Quality-of-life assessment, adverse events, and specifically the proportion with a tendon rupture, were not reported.We did not perform subgroup analysis to assess differences in outcome between arthroscopic or open surgical excision, as we did not identify more than one study with a common comparator.

AUTHORS' CONCLUSIONS

We are uncertain if surgery is beneficial over other therapeutic interventions, namely eccentric exercises or injectables. Low-certainty evidence shows that surgery for patellar tendinopathy may not provide clinically important benefits over eccentric exercise in terms of pain, function or participant-reported treatment success, but may provide clinically meaningful pain reduction and treatment success when compared with sclerosing injections. However, further research is likely to change these results. The evidence was downgraded two levels due to the small sample sizes and susceptibility to bias. We are uncertain if there are additional risks associated with surgery as study authors failed to report adverse events. Surgery seems to be embedded in clinical practice for late-stage patella tendinopathy, due to exhaustion of other therapeutic methods rather than evidence of benefit.

Patellar Tendon Strain Associates to Tendon Structural Abnormalities in Adolescent Athletes

High mechanical strain is thought to be one of the main factors for the risk of tendon injury, as it determines the mechanical demand placed upon the tendon by the working muscle. The present study investigates the association of tendon mechanical properties including force, stress and strain, and measures of tendon micromorphology and neovascularization, which are thought to be indicative of tendinopathy in an adolescent high-risk group for overuse injury. In 16 adolescent elite basketball athletes (14–15 years of age) we determined the mechanical properties of the patellar tendon by combining inverse dynamics with magnetic resonance and ultrasound imaging. Tendon micromorphology was determined based on a spatial frequency analysis of sagittal plane ultrasound images and neovascularization was quantified as color Doppler area. There was a significant inverse relationship between tendon strain and peak spatial frequency (PSF) in the proximal tendon region (r = −0.652, p = 0.006), indicating locally disorganized collagen fascicles in tendons that are subjected to high strain. No such associations were present at the distal tendon site and no significant correlations were observed between tendon force or stress and tendon PSF as well as between tendon loading and vascularity. Our results suggest that high levels of tendon strain might associate to a micromorphological deterioration of the collagenous network in the proximal patellar tendon, which is also the most frequent site affected by tendinopathy. Neovascularization of the tendon on the other hand seems not to be directly related to the magnitude of tendon loading and might be a physiological response to a high frequency of training in this group. Those findings have important implications for our understanding of the etiology of tendinopathy and for the development of diagnostical tools for the assessment of injury risk.

Treatment of patella tendinopathy by distalising tibial tubercle osteotomy

Patella tendinopathy condition is often resistant to conservative treatment. We report a case of patella tendinopathy treated by distalisation of the tibial tubercle with excellent long-term result.

Quadriceps tendinopathy: a review, part 2-classification, prognosis, and treatment

Overuse injuries of the extensor mechanism of the knee are common in both athletes and non-athletes and usually occur during activities associated with repetitive loading, stress, and knee extension. Numerous reports have been published describing extensor mechanism injuries in athletes, but there is a paucity of studies that focus on quadriceps tendinopathy in the non-athlete population. In addition, there is no universally accepted classification system for tendon pathology. Therefore, we performed a comprehensive literature review of these studies. This review consists of 2 parts. In the previous part we reviewed: (I) epidemiology and (II) diagnosis of quadriceps tendinopathy in the athlete as well as the general population. In this part we discuss: (I) classification; (II) prognosis; and (III) treatment results.

Quadriceps tendinopathy: a review-part 1: epidemiology and diagnosis

Overuse injuries of the extensor mechanism of the knee are common in both athletes and non-athletes and usually occur during activities associated with repetitive loading, stress, and knee extension. Historically, they have been labeled as Jumper's knee due to the high prevalence seen in the athletic community. In many published reports, the name "patellar tendinopathy" is used to describe this disorder of the quadriceps tendon at the patellar insertion, and the names are often used interchangeably. Numerous reports have been published describing extensor mechanism injuries in athletes, but there is a paucity of studies that focus on quadriceps tendinopathy. In addition, there is no universally accepted classification system for tendon pathology. Therefore, we performed a comprehensive literature review of these studies. This review consists of 2 parts. In the first part we review: (I) epidemiology and (II) diagnosis of quadriceps tendinopathy in the athlete as well as the general population. In the second part we discuss: (I) classification; (II) prognosis; and (III) treatment results.

Patella tendinopathy Zoobiquity - What can we learn from dogs?

BACKGROUND

Patella tendinopathy is an overuse condition. Pathogenesis and identification of intrinsic risk factors have largely eluded the orthopaedic world. The cranial cruciate ligament (CrCL) in dogs is the equivalent to the human anterior cruciate ligament (ACL). We report the effect of two canine proximal tibial osteotomy procedures in the veterinary literature on patella tendon moment arm and describe the biomechanical rationale for a tibial tubercle osteotomy for treatment of patella tendinopathy in the human.

METHODS

A literature review of studies reporting clinical complications of TTA and TPLO to form an observational animal cohort study in dogs.

RESULTS

The veterinary literature reports an overall clinical complication rate of up to 61% for TTA and up to 50% for TPLO respectively. Complications associated with the extensor mechanism of the knee are <1% for TTA compared to 1.9-19% for TPLO. Radiographic thickening of the patella tendon and tendinopathy is seen in one to 80% of TPLO cases. The TPLO decreases the moment arm of the extensor mechanism meaning increased force is required in the patella tendon to achieve the same torque when compared to the TTA which increases the efficiency of the extensor mechanism. This difference may account, in part, for the post-operative complications reported to the patella and patella tendon following TPLO.

CONCLUSION

This observational animal cohort study demonstrates a biomechanical rationale for investigating diagnostic and potential treatment options, including a tibial tubercle osteotomy, for patella tendinopathy in humans based on this principle.

Evaluation of Intrinsic Biomechanical Risk Factors in Patellar Tendinopathy: A Retrospective Radiographic Case-Control Series

Background

Patellar tendinopathy is an overuse condition often affecting athletes. It has been postulated that patellar tendinopathy is associated with patella alta; however, this and any other anatomic risk factors have not been identified.

Purpose

To explore whether lever arm differences from radiographic measurements exist between patients with and without tendinopathy. This may provide surgeons with a simple radiographic means to identify patients at risk.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Magnetic resonance imaging scans of the knee from a sports imaging facility were screened and reviewed to identify 2 groups of patients: those with and those without imaging signs of patellar tendinopathy. The lateral radiographs were reviewed and measurements made to determine (1) lever arm ratio, (2) moment arm ratio, (3) angle between the moment and line of pull of the patellar tendon, (4) patellar tendon pivot point angle, and (5) patellar height (alta). Measurements were obtained directly from radiographs. The images and measurements were reviewed by 2 experienced orthopaedic clinicians.

Results

A total of 105 patients were included in this study: 52 with patellar tendinopathy and 53 without patellar tendinopathy (controls). The mean age was similar between groups (23 years); females accounted for 8 of 52 patients with patellar tendinopathy and 24 of 53 patients without. The lever arm ratio in the group with patellar tendinopathy versus controls was 1.71 versus 1.01 (P = .01), with a moment arm difference of 1.00 versus 0.80 (P < .01), respectively. There was no difference detected between groups for patellar tendon angle, patellar tendon pivot point angle, knee flexion angle, or incidence of patella alta. No correlation was found with our measurements and the Insall-Salvati ratio. Statistical analysis was also performed according to sex, and a statistically significant difference between groups was found for differences in lever arm ratio and moment arm.

Conclusion

The lever arm ratio and moment arm ratio from lateral radiographs were significantly different between patients with and without patellar tendinopathy. Further study is needed on the biomechanical implications of the pivot point and how altering it can affect stress within the patellar tendon, patellofemoral joint, and associated clinical outcomes.

Biomechanics of the knee extensor mechanism and its relationship to patella tendinopathy: A review

The term jumpers knee for patella tendinitis, as coined by Dr. Martin Blazina, is now commonly referred to as tendinopathy. He believed it was associated with patella alta. Since then multiple studies have failed to reliably show an association between patella tendinopathy and associated intrinsic risk factors. There is, unfortunately, a well-established doctrine that the extensor mechanism is simply a pulley. The goal of the review is to examine the biomechanics of the extensor mechanism and apply this to studies investigating intrinsic risk factors for patella tendinopathy. A better understanding of the biomechanics of the extensor mechanism may stimulate the discovery of intrinsic risk factors for developing patella tendinopathy, and subsequent surgical options to address them. Clinical significance: The aim of this review is to direct future research into biomechanical risk factors for developing patella tendinopathy and subsequently, possible treatments. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3105-3112, 2018.

Revision Surgery for Failed Patellar Tendinopathy Exploration

Chronic patellar tendinopathy affects athletes, with a higher incidence in high-impact sporting activities. It can seriously impair sports activities. Many patients respond well to conservative treatment, but about 10% of them are refractory to conservative treatment. In these cases, surgery is indicated. Multiple surgical techniques have been reported, including both open and arthroscopic procedures with good results. However, in a small percentage of patients surgery is unsuccessful. This group of patients presents a major challenge, as options are limited. We describe our surgical approach in the management of recalcitrant patellar tendinopathy.

Prognostic value of MRI in arthroscopic treatment of chronic patellar tendinopathy: a prospective cohort study

Background

To date, prognostic outcome factors for patients undergoing arthroscopic treatment due to chronic patellar tendinopathy (PT) are lacking. The purpose of this study was to investigate whether preoperatively assessed MRI parameters might be of prognostic value for prediction of functional outcome and return to sports in arthroscopic treatment of chronic PT.

Methods

A prospective cohort study was conducted including 30 cases (4 female and 24 male competitive athletes) undergoing arthroscopic patellar release (APR) due to chronic PT. The mean age was 28.2 years (range, 18–49 years) at the time of surgery, and the mean follow-up period was 4.2 years (range, 2.2–10.4 years). Preoperatively assessed MRI parameters included bone marrow edema (BME) of the inferior patellar pole, patellar tendon thickening, infrapatellar fat pad (IFP) edema, and infrapatellar bursitis. Prevalences of preoperative MRI findings were correlated to functional outcome scores in order to determine statistically significant predictors.

Results

All athletes regained their preinjury sports levels. Athletes featuring preoperative IFP edema showed significantly inferior modified Blazina score (0.6 ± 0.7 vs. 0.2 ± 0.5), single assessment numeric evaluation (SANE; 86.0 ± 8.8 vs. 94.3 ± 7.5), and Visual Analogue Scale (VAS; 1.0 ± 1.2 vs. 0.3 ± 0.8) compared to subjects without IFP edema (p < 0.05). Return to sports required a mean of 4 ± 3.2 months. On average, patients with IFP edema needed significantly more time to return to sports than subjects without IFP edema (6.5 vs 2.8 months; p < 0.05). The simultaneous presence of BME and IFP edema was associated with significantly inferior outcomes by means of the Victorian Institute of Sport Assessment questionnaire for patients with patellar tendinopathy (VISA-P; 88.1 ± 11.9 vs. 98.6 ± 4.2), SANE (84.3 ± 10.2 vs. 93.1 ± 8.3), and VAS (1.3 ± 1.4 vs. 0.3 ± 0.9) compared to an isolated BME or isolated IFP edema.

Conclusions

This is the first study identifying prognostic outcome factors in arthroscopic treatment of chronic PT. Preoperative IFP edema alone or simultaneous BME and IFP edema on preoperative MRI were associated with inferior functional outcome and delayed return to sports. Knowledge of these predictive factors might improve risk stratification, individualize treatment and postoperative rehabilitation, and contribute to improve clinical outcome. Moreover, current findings offer the potential for novel therapeutic approaches.

Open Patellar Tendon Tenotomy and Debridement Combined with Suture-bridging Double-row Technique for Severe Patellar Tendinopathy

OBJECTIVE

To create a new surgical procedure for chronic severe patellar tendinopathy and to evaluate its clinical efficacy.

METHODS

In this retrospective study, the data of 12 patients with severe patellar tendinopathy in 14 knees who had undergone surgical treatment at Beijing Chao-Yang Hospital between 1 March 2009 and 1 August 2013 were analyzed. Inclusion criteria included severe patellar tendinopathy (Phase III), conservative therapy for more than 6 months, American Society of Anesthesiology status Grade I-II, and body mass index <30. Patients with severe osteoporosis, complete tendon disruption (Phase IV) and those who were unable to cooperate were excluded. There were 8 men (10 knees) and 4 women (4 knees) cases. The patients' ages ranged from 38 to 54 years (mean, 45.3 years). All surgeries had been performed by the same physician. Surgical treatment comprised incising open patellar midline tenotomy, complete debridement and suture-bridging double-row fixation. Isotonic and kinetic chain exercises were implemented after the second post-operative week. A gradual increase to full weight-bearing was allowed after the third post-operative week and a gradual return to unrestricted use of the leg after the eighth post-operative week. Preoperative and postoperative visual analogue scale (VAS) scores and Lysholm knee scores were obtained from the medical records or at recent postoperative follow-up visits and the results compared using Student's two-tailed paired t-test.

RESULTS

VAS scores decreased by a mean of 6.7 points (range, 1.1-7.8 points) during follow-up (minimum duration 14 months; range, 14-44 months) and Lysholm scores increased from 55.7 ± 6.5 points to 90.4 ± 6.2 points. Three cases (4 knees) achieved excellent outcomes (≥95 points) and 9 cases (10 knees) good outcomes (range, 86-94 points). No intraoperative or postoperative complications occurred. There were significant differences between preoperative and postoperative VAS and Lysholm scores (P < 0.01).

CONCLUSIONS

All study patients achieved good or excellent outcomes. No patellar tendon rupture or suture fixation failure occurred during follow-up. Suture-bridging double-row fixation is a simple and reliable method that not only improves patients' clinical symptoms, but also restores knee joint function.

MRI of the knees in asymptomatic adolescent soccer players: A case-control study

PURPOSE

To determine the range of asymptomatic abnormal findings in adolescent soccer players at 3.0T MRI of the knee.

MATERIALS AND METHODS

In all, 87 knees of asymptomatic 14-17-year-old male adolescents were evaluated at 3T, using a standardized examination protocol comprising four sequences: two fat-suppressed T₂ -weighted fast spin-echo sequences (T₂ FSE), in the sagittal (repetition time / echo time [TR/TE], 5.300/71, echo train length [ETL] 17) and coronal planes (TR/TE, 4234/70, ETL 17), one fat-suppressed proton density (PD) sequence in the axial plane (TR/TE, 2.467/40, ETL 9), and one T₁ -weighted spin-echo (T₁ SE) sequence in the sagittal plane (TR/TE, 684/12.5). Soccer players (46 knees) were paired with controls (41 knees) by age and weight. Bone marrow, articular cartilage, meniscus, tendons, ligaments, fat pad abnormalities, and joint fluid were assessed.

RESULTS

One or more abnormalities were detected in 31 knees (67.4%) in the soccer player group, compared to 20 knees (48.8%) in the control group. The prevalence of bone marrow edema was higher in the soccer group (19 knees, 41.3%) than in the control group (3 knees, 7.3%), P = 0.001. Other abnormalities found in this sample (joint effusion, cartilage lesions, tendinopathy, ganglion cysts, and infrapatellar fat pat edema) were not significantly different between the two study groups.

CONCLUSION

Asymptomatic adolescents had a high prevalence of abnormal findings on knee imaging, especially bone marrow edema. This prevalence was higher among soccer players.

LEVEL OF EVIDENCE

4 J. Magn. Reson. Imaging 2017;45:59-65.

Results of Surgical Treatment of Chronic Patellar Tendinosis (Jumper's Knee): A Systematic Review of the Literature

PURPOSE

To review the literature concerning surgical treatment options for chronic patellar tendinosis (jumper's knee), a common problem among athletes. When conservative treatment fails, surgical treatment is required.

METHODS

Systematic review of the literature concerning the results of current surgical treatment options for chronic patellar tendinosis. All articles of studies with an evidence level ≥IV from January 2000 until February 2015 presenting the surgical outcome after arthroscopic as well as open treatment of chronic patellar tendinosis were included. The literature research of the PubMed database was performed using the following key words: "patellar" and "tendinitis," "tendonitis," "tendinosis" or "tendinopathy"; "inferior patellar pole"; "jumper's knee"; "surgical treatment" and "open" or "arthroscopic patellar tenotomy."

RESULTS

A systematic review of the literature was performed especially to point out the effectiveness of arthroscopic treatment of chronic patellar tendinosis. The results revealed good clinical results for arthroscopic as well as open treatment of chronic patellar tendinosis that is refractory to conservative treatment in athletes. An average success rate of 87% was found for the open treatment group and of 91% for the arthroscopic treatment group. However, after open surgery, the mean time of return to the preinjury level of activity is 8 to 12 months, with a certain number of patients/athletes who cannot return to the preinjury level of activity.

CONCLUSIONS

Minimally invasive, arthroscopically assisted or all-arthroscopic procedures may lead to a significantly faster return to sporting activities and may, therefore, be the preferred method of surgical treatment.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

Patellar tendinopathy: late-stage results from surgical treatment

Objective

To evaluate the late-stage results from surgical treatment of patellar tendinopathy (PT), using the Visa score (Victorian Institute of Sport Tendon Study Group) and the Verheyden method.

Methods

This was a retrospective study in which the postoperative results from 12 patients (14 knees) who were operated between July 2002 and February 2011 were evaluated. The patients included in the study presented patellar tendinopathy that was refractory to conservative treatment, without any other concomitant lesions. Patients who were not properly followed up during the postoperative period were excluded.

Results

Using the Verheyden method, nine patients were considered to have very good results, two had good results and one had poor results. In relation to Visa, the mean was 92.4 points and only two patients had scores less than 70 points (66 and 55 points).

Conclusion

When surgical treatment for patellar tendinopathy is correctly indicated, it has good long-term results.

Clinical results after ultrasound-guided intratissue percutaneous electrolysis (EPI®) and eccentric exercise in the treatment of patellar tendinopathy

PURPOSE

To investigate the outcome of ultrasound (US)-guided intratissue percutaneous electrolysis (EPI(®)) and eccentric exercise in the treatment of patellar tendinopathy during a long-term follow-up.

METHODS

Forty patients with patellar tendinopathy were prospectively evaluated over a 10-year follow-up period. Pain and function were evaluated before treatment, at 3 months and at 2, 5 and 10 years using the Victorian Institute of Sport Assessment-Patella (VISA-P) score, the Tegner score and Blazina's classification. According to VISA-P score at baseline, patients were also dichotomized into Group 1 (<50 points) and Group 2 (≥50 points). There were 21 patients in Group 1 and 19 in Group 2. Patient satisfaction was measured according to the Roles and Maudsley score.

RESULTS

The VISA-P score improved globally by 41.2 points (p < 0.01) after a mean 4.1 procedures. In Group 1, VISA-P score improved from 33.1 ± 13 to 78.9 ± 14.4 at 3-month and to 88.8 ± 10.1 at 10-year follow-up (p < 0.001). In Group 2, VISA-P score improved from 69.3 ± 10.5 to 84.9 ± 9 at 3-month and to 96.0 ± 4.3 at 10-year follow-up (p < 0.001). After 10 years, 91.2 % of the patients had a VISA-P score >80 points. The same level (80 % of patients) or the Tegner score at no more than one level lower (20 % of patients) was restored, and 97.5 % of the patients were satisfied with the procedure.

CONCLUSION

Treatment with the US-guided EPI(®) technique and eccentric exercises in patellar tendinopathy resulted in a great improvement in knee function and a rapid return to the previous level of activity after few sessions. The procedure has proved to be safe with no recurrences on a long-term basis.

LEVEL OF EVIDENCE

Therapeutic study, Level IV.

MRI of anterior knee pain

Anterior knee pain is the most common knee complaint. It may be due to a variety of soft tissue or osseous abnormalities. Knowledge of the radiologic appearance of the abnormalities allows more accurate diagnosis of the cause of the pain including chondral abnormalities, patellar instability and dislocation, femoral trochlear dysplasia, abnormal patellar location, bipartite patella, various tendinopathies, bursal inflammation, traction apophysitis in pediatric and adolescent patients, and miscellaneous diseases including mediopatellar plica syndrome and Hoffa's disease. Radiographs are often obtained to exclude acute osseous abnormalities, such as fractures. Magnetic resonance (MR) imaging offers superior soft tissue contrast resolution and allows for more accurate evaluation of the underlying etiology and therefore may improve treatment and possible surgical planning.

Are multiple platelet-rich plasma injections useful for treatment of chronic patellar tendinopathy in athletes? a prospective study

BACKGROUND

Chronic patellar tendinopathy (PT) is one of the most common overuse knee disorders. Platelet-rich plasma (PRP) appears to be a reliable nonoperative therapy for chronic PT.

PURPOSE

To evaluate clinical and radiological outcomes of 3 consecutive ultrasound (US)-guided PRP injections for the treatment of chronic PT in athletes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 28 athletes (17 professional, 11 semiprofessional) with chronic PT refractory to nonoperative management were prospectively included for US-guided pure PRP injections into the site of the tendinopathy. The same treating physician at a single institution performed 3 consecutive injections 1 week apart, with the same PRP preparation used. All patients underwent clinical evaluation, including the Victorian Institute of Sport Assessment-Patella (VISA-P) score, visual analog scales (VAS) for pain, and Lysholm knee scale before surgery and after return to practice sports. Tendon healing was assessed with MRI at 1 and 3 months after the procedure.

RESULTS

The VISA-P, VAS, and Lysholm scores all significantly improved at the 2-year follow-up. The average preprocedure VISA-P, VAS, and Lysholm scores improved from 39 to 94 (P < .001), 7 to 0.8 (P < .0001), and 60 to 96 (P < .001), respectively, at the 2-year follow-up. Twenty-one of the 28 athletes returned to their presymptom sporting level at 3 months (range, 2-6 months) after the procedure. Follow-up MRI assessment showed improved structural integrity of the tendon at 3 months after the procedure and complete return to normal structural integrity of the tendon in 16 patients (57%). Seven patients did not recover their presymptom sporting level (among them, 6 were considered treatment failures): 3 patients returned to sport at a lesser level, 1 patient changed his sport activity (for other reasons), and 3 needed surgical intervention.

CONCLUSION

In this study, application of 3 consecutive US-guided PRP injections significantly improved symptoms and function in athletes with chronic PT and allowed fast recovery to their presymptom sporting level. The PRP treatment permitted a return to a normal architecture of the tendon as assessed by MRI.

Predicting the patellar tendon force generated when landing from a jump

PURPOSE

Although high patellar tendon loading is believed to be the primary causative factor for patellar tendinopathy, research investigating factors that affect patellar tendon loading during landing is scarce. Therefore, the purpose of this study was to identify whether factors previously associated with the development of patellar tendinopathy, and selected variables characterizing landing technique, could predict patellar tendon loading incurred by volleyball players when landing from a jump.

METHODS

Ten highly skilled male, 20 skilled male, and 20 skilled female volleyball players performed a lateral stop-jump movement. Sex, skill level, quadriceps strength, quadriceps extensibility, and trunk moment of inertia were recorded. Landing kinematics (250 Hz) and kinetics (1500 Hz) were collected, and peak patellar tendon force and patellar tendon force loading rate were calculated. Backward multiple regression analyses identified which risk factors or landing technique variables were predictors of patellar tendon loading.

RESULTS

Multiple regression analyses were able to estimate and predict 52% (F4,49 = 14.258, P < 0.001) and 70% (F4,49 = 29.329, P < 0.001) of the peak patellar tendon force and the patellar tendon force loading rate variance, respectively. The present study revealed that male volleyball players with greater quadriceps strength, who displayed increased ankle dorsiflexion velocity and trunk flexion velocity during landing, were predicted to incur higher patellar tendon loading.

CONCLUSIONS

As frequent application of high patellar tendon loading has previously been identified as a causative factor for developing patellar tendinopathy, interventions designed to decrease ankle dorsiflexion velocity and trunk flexion velocity at landing, particularly in male players with strong quadriceps muscles, may be effective in reducing patellar tendon loading and, in turn, patellar tendinopathy prevalence in this population.

Reliability and Validity of the Korean Version VISA-P Questionnaire for Patellar Tendinopathy in Adolescent Elite Volleyball Athletes

Objective

To translate the English Victorian Institute of Sport Assessment for patellar tendinopathy (VISA-P) questionnaire into a Korean version and to determine the reliability and validity of the Korean version.

Methods

The English VISA-P questionnaire was translated into Korean according to the internationally recommended guidelines. Then, 28 adolescent elite volleyball athletes (average age, 16 years; range, 14 to 19 years) were asked to complete the questionnaire three times (before examination, after examination, and 1 week later) for reliability. They were evaluated through a physical examination and ultrasonography to diagnosis patellar tendinopathy.

Results

The internal consistency of the VISA-P questionnaire by Cronbach's alpha was 0.80 for the first, 0.78 for the second, and 0.79 for the third assessment. The intraclass correlation coefficient (ICC) between the first and second assessments was 0.97. The ICC between the second and third assessments was 0.96. The mean VISA-P scores were 67.6±15.7 for the patellar tendinopathy group (n=23) and 92.6±8.6 for the normal group (n=5). There were significantly lower VISA-P scores in the patellar tendinopathy group compared to the normal group.

Conclusion

The translated Korean version VISA-P questionnaire has good internal consistency, test-retest reliability and validity. In addition, this study indicated that most adolescent elite volleyball athletes had patellar tendon problems. Therefore, the Korean version VISA-P is a useful self-administered outcome score of athletes with patellar tendinopathy.

Glutamate receptors in tendinopathic patients

Tendinopathy, pain, and degeneration, may be related to the up-regulation of substance P (SP) and its activation of glutamate receptors. We hypothesized that the pathogenesis of tendinopathy involves N-methyl-D-aspartate receptor type 1 (NMDAR1) activation (phosphorylated NMDAR1; phospho-NMDAR1) co-existing with SP. Moreover, we examined the presence of metabotropic receptors that increase (mGluR1 and mGluR5) or decrease (mGluR6 and mGluR7) NMDAR1 excitability. Biopsies from patients with patellar tendinopathy (n = 10) and from controls (n = 8) were immunohistochemically analyzed according to the occurrence and tissue distribution of NMDAR1, phosho-NMDAR1, mGluR (1, 5-7), and SP. The biopsies were immunohistochemically single- and double-stained and semi-quantitatively assessed. Tendinopathic biopsies exhibited increased occurrence of NMDAR1, phospho-NMDAR1, SP, and mGluR5, while mGluR6-7 were not increased and mGluR1 was not found. The occurrence of NMDAR1 and SP correlated in tendinopathy (r(2)  = 0.54, p = 0.03), but not in the controls (r(2)  = 0.11, p = 0.4). Co-localization of SP and phospho-NMDAR1 within the tendon proper was only found in tendinopathy, localized on hypertrophic tenocytes, blood vessels, and penetrating free-nerve fibres. Up-regulation and activation of the glutamate receptor, phospho-NMDAR1, suggests a role in the pathophysiology of tendinopathy. Increased NMDAR1 excitability may be related to increased SP and mGluR5. The unique co-existence of SP and phospho-NMDAR1 in tendinopathy presumably reflects a tissue proliferative and nociceptive role.

Hyaluronan injection therapy for athletic patients with patellar tendinopathy

BACKGROUND

Patellar tendinopathy produces activity-related pain and focal tenderness at the attachment of the patellar tendon at the lower pole of the patella. It frequently causes a reduction in athletic ability. An injection of hyaluronan was found to be useful for patellar tendinopathy, provided the indication is appropriate, based on the authors' pilot cases. The purpose of this study was to summarize the clinical experience of and to describe the appropriate indication for this injection therapy.

METHODS

Fifty patients were treated from January 1999 to December 2006. The observation period averaged 25.7 months (range 6-88). All patients were graded stage 2 or 3 by Blazina's classification. Each treatment was counted separately for 9 patients (10 knees) who had more than one treatment period with 3 months or more between the injections. There were 4 bilaterally injected patients. Patellar tendinopathy was classified into 4 types according to the degree of tenderness and the regions that are tender. Hyaluronan was injected into the interface between the patellar tendon and the infrapatellar fat pad at the proximal insertion, or into the region of maximum tenderness.

RESULTS

The total number of injections was 135, and there were an average of 2.0 injections per case (range 1-11). Following treatment, 54 % of the cases were rated in excellent condition, as they were able to return to their previous athletic activities with little difficulty, while 40 % of the cases were rated in good condition-these patients were able to return to their previous sporting activities with some degree of limitation.

CONCLUSIONS

Hyaluronan injection therapy for athletic patients with patellar tendinopathy is an optional but effective treatment.

Can arthroscopically assisted treatment of chronic patellar tendinopathy reduce pain and restore function?

BACKGROUND

Patellar tendinopathy is a common source of pain in athletes, especially those involved in sports with a high incidence of jumping and cutting. Changes in training programs and exercises based on eccentric quadriceps contractions often relieve patients' symptoms. For athletes unresponsive to this treatment, some authors suggest open and arthroscopic procedures débriding either the tendon alone, or the tendon and bone.

QUESTIONS/PURPOSES

We asked whether an arthroscopically assisted approach to débride not only the tendon, bone, but also the peritenon could relieve pain and allow athletes to return to their former activities.

PATIENTS AND METHODS

We retrospectively reviewed 23 patients with a history of at least 6 months of painful patellar tendinopathy unresponsive to nonoperative treatment treated with an arthroscopic technique that débrided the tendon, inferior pole of the patella, and peritenon: 22 males and one female. Mean age was 29 years. Patients were evaluated using the anterior knee pain score of Kujala et al. The minimum followup was 12 months (mean, 58 months; range, 12-121 months).

RESULTS

Twelve patients scored 100, one 99, one 98, five 97, two 94, one 90, and one 64. The Kujala et al. mean score was 96 (range, 64-100). All but four patients returned to their former sports activities. We observed no complications.

CONCLUSIONS

Arthroscopic treatment can relieve the pain of refractory chronic patellar tendinopathy. Our observations were comparable with those previously reported for open techniques and a high percentage of patients returned to their previous activity level.

LEVEL OF EVIDENCE

Level IV, observational study. See Guidelines for Authors for a complete description of levels of evidence.

Avaliação da altura patelar em atletas com tendinopatia crônica do aparelho extensor do joelho

OBJETIVO: Avaliar radiograficamente a altura patelar de atletas com diagnóstico de tendinopatia crônica do aparelho extensor do joelho (TCAE). MÉTODOS: Na amostra foram avaliados radiograficamente 65 pacientes (110 joelhos) com idade entre 15 e 40 anos e de diferentes modalidades esportivas com e sem diagnóstico de tendinopatia crônica do aparelho extensor do joelho (jumper's knee). Os atletas foram divididos em dois grupos: aqueles com diagnóstico de TCAE (grupo 1: 38 atletas - 56 joelhos) e um grupo que denominamos de controle (grupo 2: 27 atletas - 54 joelhos). RESULTADOS: No grupo 1 tivemos 18 atletas que apresentavam a doença bilateralmente na ocasião dos exames. Para a medida da altura patelar utilizamos os índices radiográficos de Insall e Salvati e Blackburne e Peel. CONCLUSÃO: A presença de patela alta no grupo de atletas com tendinopatia crônica do aparelho extensor do joelho foi significante maior do que a observada no grupo controle.

Deciphering the pathogenesis of tendinopathy: a three-stages process

Our understanding of the pathogenesis of "tendinopathy" is based on fragmented evidences like pieces of a jigsaw puzzle. We propose a "failed healing theory" to knit these fragments together, which can explain previous observations. We also propose that albeit "overuse injury" and other insidious "micro trauma" may well be primary triggers of the process, "tendinopathy" is not an "overuse injury" per se. The typical clinical, histological and biochemical presentation relates to a localized chronic pain condition which may lead to tendon rupture, the latter attributed to mechanical weakness. Characterization of pathological "tendinotic" tissues revealed coexistence of collagenolytic injuries and an active healing process, focal hypervascularity and tissue metaplasia. These observations suggest a failed healing process as response to a triggering injury. The pathogenesis of tendinopathy can be described as a three stage process: injury, failed healing and clinical presentation. It is likely that some of these "initial injuries" heal well and we speculate that predisposing intrinsic or extrinsic factors may be involved. The injury stage involves a progressive collagenolytic tendon injury. The failed healing stage mainly refers to prolonged activation and failed resolution of the normal healing process. Finally, the matrix disturbances, increased focal vascularity and abnormal cytokine profiles contribute to the clinical presentations of chronic tendon pain or rupture. With this integrative pathogenesis theory, we can relate the known manifestations of tendinopathy and point to the "missing links". This model may guide future research on tendinopathy, until we could ultimately decipher the complete pathogenesis process and provide better treatments.

Surgical treatment of patellar tendinopathy in athletes. A retrospective multicentric study

The purpose of this study was to evaluate the results of surgery, in particular arthroscopic procedures in the treatment of patellar tendinopathies that are refractory to conservative treatment in athletes.

METHOD

A retrospective multicenter study was performed in four centers. Patients were athletes who did not respond to carefully followed conservative treatment and who underwent surgery. Sixty-four patients were included, 10 who underwent arthroscopy. Patients were questioned and followed-up for an average of 22 months (6-116 months).

RESULTS

At the final follow-up, 87% of the patients had an improved Blazina score and 63% were again practicing their sport at the same level. None of the preoperative factors influenced the final result and one surgical technique was not more effective than another (patellar tip resection versus arthroscopic approach).

DISCUSSION

The results of this study are comparable to those in the literature which show a success rate of more than 80% whatever the surgical technique. This study limits a certain number of biases because the patient group is homogenous (athletes, unsuccessful conservative treatment) with similar functional scores, and well-defined protocols for postoperative rehabilitation. However, the study of this entity is difficult because of the limited number of subjects and its different anatomopathological forms.

CONCLUSION

Surgical treatment is indicated in motivated athletes if carefully followed conservative treatment is unsuccessful after more than six months, making it impossible to practice a sport (Blazina grade 3). Arthroscopic techniques seem to be as effective as open surgery with an equivalent delay for beginning sports activities.

Arthroscopic resection of the lower patellar pole in patients with chronic patellar tendinosis

PURPOSE

The aim of this prospective study is to evaluate the clinical results of arthroscopic resection of the lower patellar pole in patients with patellar tendinosis.

METHODS

Twenty patients underwent an arthroscopic resection of the lower patellar pole between 2002 and 2004. All of them were evaluated at 6 weeks and 3, 6, 12, and 24 months after surgery using the Tegner activity level, the Lysholm score, the Kujala score, a modified jumper's knee classification according to Blazina, and visual analog scales for pain, function, and satisfaction. Clinical evaluation was performed 2 years after surgery. In addition, magnetic resonance imaging was performed preoperatively and at a 2-year follow-up.

RESULTS

By 6 weeks postoperatively and at every other follow-up visit, significant improvements were seen in the Lysholm score (P = .001), the Kujala score (P = .001) and the visual analog scales. The Tegner score improved significantly by 3 months postsurgery (P = .01). Two years after surgery, the Tegner score improved from 4.4 +/- 2.9 to 7.95 +/- 1.6 (P < .0001); the Lysholm score from 57.1 +/- 17.1 to 97.3 +/- 4.4 (P < .0001); and Kujala score from 53.7 +/- 14.7 to 95.4 +/- 7.8 (P < .0001). The jumper's knee classification showed excellent (stage 0) or good (stage I) results in 18 of 20 patients. At follow-up, all but one magnetic resonance image showed hypodens areals in the proximal aspect of the patellar tendon, and small osteophytes were seen in some cases at the resection area. These findings did not seem to have any influence on the results.

CONCLUSIONS

The arthroscopic resection of the lower patellar pole as a minimal invasive method to treat jumper's knee provides satisfactory clinical results in knee function and pain reduction with fast recovery and return to sport activities.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Surgical treatment of chronic patellar tendinosis: a systematic review

There is no consensus in the literature on the best surgical procedure for patellar tendinosis when nonoperative treatment fails. With a systematic review, we asked whether surgical treatment of the inferior pole of the patella, closing of the paratenon, or immobilization affected the percentage of patients reporting good to excellent results (percent success). We completed a systematic review of surgical treatment for patellar tendinosis. A literature search of Medline, CINAHL, and Sport Discus revealed 30 articles on treatment of patellar tendinosis. Ten met our initial inclusion criteria. Most studies were retrospective and used varying techniques. Outcome measures were individual to the specific article, making it difficult to compare the results of the studies. Studies that described surgical treatment of the inferior pole of the patella had 70.9% success compared to 91.7% for those that performed no patella bony work. Closure of the paratenon was reported in seven studies with 84.8% success compared to 91.5% for the other studies. Immobilization was used in four studies with 82.4% success compared to 94.9% success for four studies that did not immobilize postoperatively. Care must be taken when comparing these weighted averages since only two of the nine studies described exactly the same technique. Ideally, prospective controlled studies with validated assessment tools and activity scores are required to determine the best treatment for our patients.