The Incidence And Occupational Outcome Of Overuse Anterior Knee Pain During Army Recruit Training

A Comprehensive Summary of the Meta-Analyses and Systematic Reviews on Platelet-Rich Plasma Therapies for Knee Osteoarthritis

INTRODUCTION

Osteoarthritis (OA), including that of the knee joint, represents a significant proportion of musculoskeletal injuries in the Canadian Armed Forces (CAF) due to the frequent, high-stress physical activity for which member participation is necessary. Platelet-rich plasma (PRP) is a conservative, autologous treatment that has the potential to relieve symptoms and improve functionality of military members to decrease the impact of the disease and ultimately strengthen the CAF.

MATERIALS AND METHODS

A search of systematic reviews and meta-analyses was conducted to determine the efficacy of PRP injections in treating knee OA. The Scopus database, PubMed database, and Omni academic search tools were scoped for relevant publications. English literature, published up to and including March 2023, that investigated only clinically randomized controlled trials (RCTs) was eligible for inclusion. The results of network meta-analyses were investigated and summarized independent of reviews and non-network meta-analyses.

RESULTS

A total of 225 unique systematic reviews and meta-analyses were initially identified, of which 39 publications, including 7 network meta-analyses, adhered to the defined inclusion and exclusion criteria. PRP was found to significantly alleviate symptoms of pain based on the visual analog scale and Western Ontario and McMaster Universities Arthritis Index pain scores within the 12-month follow-up. Function, activity, sport, quality of life, and stiffness were additionally determined to generally improve to a greater extent from PRP treatment compared to controls, while adverse effects were minor and temporary. PRP placed in the top 3 in 9 reported surface under the cumulative ranking curves, while individually reported rankings of leukocyte-poor and leukocyte-rich PRP both placed in the top 4. The clinical recommendations made were generally positive, with 17 publications acknowledging the benefits of PRP, 3 supporting possible efficacy, and an additional 8 recommending that it be an option for the conservative treatment of knee OA.

CONCLUSION

The results of this review support the efficacy of PRP for relieving symptoms of pain and improving function, stiffness, and quality of life for patients experiencing knee OA within 12 months. As a result, leukocyte-poor-PRP could be considered for members of the CAF with mild to moderate knee OA (Kellgren-Lawrence grades 1-3) to slow the progression of OA and extend the military careers of CAF members. There continues to be a need for future studies to investigate the longer-term effects of PRP to verify sustained benefits at follow-up points greater than 12 months, including findings of improvement in a delayed fashion at the 3- and 6-month timeframe compared to hyaluronic acid treatment.

The association between kinesiophobia and functional limitations in service members with knee pain

BACKGROUND

Knee diagnoses account for more than 50% of lower extremity musculoskeletal conditions in non-deployed US Service members. However, there is limited information regarding kinesiophobia in Service members with non-operative knee diagnoses.

HYPOTHESES

The objectives of this study were to determine the prevalence of high levels of kinesiophobia in US military Service members with knee pain across different knee diagnoses, and to determine the relationships between kinesiophobia and lower extremity function and/or specific functional limitations in Service members with knee pain. It was hypothesized Service members with knee pain would exhibit high levels of kinesiophobia across all knee diagnoses examined, and higher levels of both kinesiophobia and pain would be associated with worse self-reported function in this population. It was also hypothesized higher levels of kinesiophobia would be associated with functional activities with high knee loading.

DESIGN

Retrospective cohort study.

LEVEL OF EVIDENCE

IV.

METHODS

Sixty-five US Service members presenting to an outpatient physical therapy clinic were included in this study (20 females; age = 30.8 ± 7.7 years; height = 1.74 ± 0.9 m; mass = 80.7 ± 16.2 kg). Inclusion criterion was the presence of knee pain (duration = 50 ± 59 months); exclusion criterion was knee pain as a sequela of knee surgery. Data regarding demographic, pain chronicity, pain by Numeric Rating Scale (NRS), Tampa Scale of Kinesiophobia (TSK), and Lower Extremity Functional Scale (LEFS) were retrospectively obtained from patients' medical records. A high level of kinesiophobia was defined as a TSK score of greater than 37 points. Patient diagnoses included: osteoarthritis (n = 16); patellofemoral pain syndrome (n = 23); and other non-operative knee diagnoses (n = 26). Commonality analysis was utilized to determine the effects of age, height, mass, NRS, and TSK on LEFS score. Predictor values were interpreted as <1% = negligible, >1% = small; >9% = moderate, >25% = large. Additionally, exploratory item-specific analyses examined the strength of the relationships between kinesiophobia and LEFS item responses. Binary logistic regression determined if difficulty with an individual LEFS item could be predicted from either NRS or TSK score. Statistical significance was set at P < 0.05.

RESULTS

High levels of kinesiophobia were identified in 43 individuals (66%). NRS and TSK explained 19.4% and 8.6% of the unique variance in LEFS, and 38.5% and 20.5% of total variance, respectively. Age, height, and mass explained negligible to small proportions of the unique variance in LEFS. TSK and NRS were independent predictors for 13/20 individual LEFS items, with odds ratios ranging from 1.12 to 3.05 (P < 0.05).

CONCLUSION

The majority of US Service members in this study exhibited high levels of kinesiophobia. Kinesiophobia was significantly related to self-reported functional scores and performance on individual functional tasks in Service members with knee pain.

CLINICAL RELEVANCE

Treatment strategies addressing both fear of movement and pain reduction in patients with knee pain may help optimize functional outcomes.

Botulinum neurotoxin type A improves vasti muscle balance, patellar tracking, and pain in patients with chronic patellofemoral pain

The purpose of this study was to determine the effects of botulinum neurotoxin type A (BoNT-A) on vastus lateralis:vastus medialis (VL:VM) muscle balance, patellar tracking, and pain in patients with chronic patellofemoral (PF) pain. We recruited 13 participants (9 females, 4 males) with recalcitrant PF pain who underwent ultrasound-guided BoNT-A injections into the distal third of the VL muscle, followed by a 6-week home exercise program to strengthen their VM muscle. We imaged the participants in a C-arm computed tomography (CT) scanner before and after the intervention. We calculated VL:VM ratios from CT images from a supine, nonweight-bearing condition. We obtained patellar tilt and bisect offset values from CT images from an upright, weight-bearing condition. We recorded functional pain scores before, immediately after, and 2-4 years after the intervention. We classified the participants into normal tracking and maltracking groups based on their patellar tilt and bisect offset values. BoNT-A with home exercise reduced VL:VM ratio (18%; p < 0.001), patellar tilt (19%; p = 0.020), and bisect offset (5%; p = 0.025). Four participants classified as maltrackers before the intervention transitioned to normal tracking after the intervention. Functional pain scores improved immediately after the intervention (13%, p < 0.001) and remained improved at 2-year follow-up (12%, p = 0.011). Statement of Clinical Significance: This study provides new evidence in support of BoNT-A for treatment of PF pain. Classification of patients under weight-bearing conditions may identify individuals who will most benefit from a BoNT-A treatment.

Anterior Knee Pain Risk Differs Between Sex and Occupation in Military Tactical Athletes

CONTEXT

Anterior knee pain (AKP) is ubiquitous in early-career military members and exacerbated during functional tasks required during military duties. Therefore, it is important to understand risk of this condition in male and female tactical athletes in diverse military occupations.

OBJECTIVE

To assess sex and occupation on AKP risk in military members.

DESIGN

Descriptive Epidemiology Study.

SETTING

United States Armed Forces. Patients All military members diagnosed with anterior or retro-patellar pain, patellar instability, knee tendinopathy on their initial encounter from 2006 to 2015.

OUTCOME MEASURES

The Defense Medical Epidemiology Database was queried for the number of individuals with AKP. Relative risk (RR) and chi-square statistics were calculated in the assessment of sex and occupational category. Regressions were calculated to determine association between service branch, sex, and AKP across time.

RESULTS

From 2006-2015, a total of 151,263 enlisted and 14,335 officer services members were diagnosed with AKP. Enlisted females had an incidence rate of 16.7 per 1000 person-years compared to the enlisted male service members with an incidence rate of 12.7 per 1000 person-years (RR: 1.32, 95%CI: 1.30-1.34, p<0.001) across all AKP diagnoses. Female officers had an incidence rate of 10.7 per 1,000 person-years compared to male officers at an incidence rate of 5.3 per 1000 person-years (RR: 2.01, 95%CI: 1.94-2.09). Differences in risk were also noted across military occupation for both enlisted and officer service members (p<.05).

CONCLUSION

Sex and military occupation were salient factors for AKP risk. Evaluation of training requirements and developing interventions programs across military occupation could serve as a focus for future research aiming to mitigate associated risk factors of AKP.

Cryoablation of the Infrapatellar Branch of the Saphenous Nerve Identified by Non-Invasive Peripheral Nerve Stimulator for the Treatment of Non-Surgical Anterior Knee Pain: A Case Series and Review of the Literature

Chronic, non-surgical, non-specific anterior knee pain is a common source of functionally limiting chronic ailment, especially in a young athletic and active-duty military population. The infrapatellar branch of the saphenous is becoming a common therapeutic target for the diagnosis and treatment of anterior knee pain. It is a nerve commonly injured during knee surgeries and trauma, resulting in neuroma formation and chronic neuropathic pain states, and it can also transmit nociceptive input from patients with non-surgical anterior knee pain of multiple etiologies. Several methods have been employed to treat this condition. After the diagnosis of infrapatellar saphenous neuralgia, the nerve is safely ablated using radiofrequency ablation, neurolytic solutions, and, most recently, cryoablation using the handheld iovera® cryoablation system (Myoscience, Inc. Fremont, CA). Cryoablation is an attractive technique because it is minimally invasive, not permanent, and well tolerated by the patient with only local anesthesia. We have previously described a technique using a non-invasive peripheral nerve stimulator to identify and treat the exact location of the nerve more precisely, thereby optimizing treatment success and procedural simplicity. This case series illustrates our initial use and success with this technique. Further follow-up and randomized sham-controlled trials are also planned.

Distance travelled by military recruits during basic training is a significant risk factor for lower limb overuse injury

INTRODUCTION

Military initial training results in a high incidence of lower limb overuse injuries (stress fractures and medial tibial stress syndrome). This study aimed to determine whether the distance travelled by recruits, both on and off duty, was a risk factor for overuse injury.

METHODS

14 male airborne infantry recruits from three training platoons carried global positioning system receivers throughout the first 19 weeks of basic military training. Total distance travelled each day was recorded. This was compared with time of clinical manifestation of 52 lower limb overuse injuries (stress fractures and medial tibial stress syndrome) collected from the 276 airborne infantry recruits in the period immediately preceding the study.

RESULTS

Recruits travelled significantly farther than the UK average male population in 17 of 18 measured weeks. Pearson correlation between distance travelled per week and injuries was not significant (p=0.4448); however, correlation between distance travelled per week and injuries two weeks later was significant (p=0.0263). A generalised linear model found distance travelled as a significant covariate (p=0.0144) to the expected number of injuries two weeks later.

CONCLUSION

Recruits travel long distances during basic training, particularly in the first few weeks when they are not yet conditioned. This distance travelled is likely a contributing risk factor to the high incidence of overuse injuries seen during training, and strategies to reduce this distance should be explored.

Effects of a contoured foot orthosis and flat insole on plantar pressure and tibial acceleration while walking in defence boots

This study investigated the effects of a contoured, prefabricated foot orthosis and a flat insole on plantar pressure and tibial acceleration while walking in defence boots. Twenty-eight adults walked along an 8-metre walkway in a: (i) defence boot (control condition), (ii) defence boot with a flat insole, and (iii) defence boot with a contoured foot orthosis. Plantar pressure data were collected using the pedar-X in-shoe system and tibial accelerations were measured with an accelerometer. In relation to plantar pressure under the rearfoot, the contoured foot orthosis, compared to the defence boot, decreased peak pressure and maximum force, and increased contact area. Under the medial midfoot, the contoured foot orthosis and flat insole increased peak pressure, maximum force and contact area. Under the medial forefoot, the contoured foot orthosis and flat insole increased maximum force. Under the lateral forefoot, the contoured foot orthosis and flat insole increased contact area, with the flat insole also increasing maximum force. In relation to tibial acceleration, the contoured foot orthosis, compared to the defence boot, decreased tibial peak positive acceleration. These findings provide novel biomechanical evidence for the effects of contoured foot orthoses in defence boots.

Chondromalacia Patella among Military Recruits with Anterior Knee Pain: Prevalence and Association with Patellofemoral Malalignment

BACKGROUND

The aim of this study was to investigate the frequency of chondromalacia patella (CMP) and to evaluate its relation with trochlear morphometric and patellofemoral alignment measurements as well as with edema in superolateral region of Hoffa's fat pad (SHFP) in military recruits with anterior knee pain (AKP).

MATERIALS AND METHODS

Knee magnetic resonance imaging examinations of 288 military recruits with AKP were retrospectively evaluated. Patellar cartilage lesions were graded using modified Noyes system. Quantitative measurements of trochlear morphology (sulcus angle, trochlear sulcus depth, and lateral trochlear inclination [LTI]) and patellofemoral alignment (patellar translation [PT], lateral patellofemoral angle (LPA), Insall-Salvati index, and tibial tuberosity-trochlear groove distance) were made. The SHFP region was assessed for the presence of edema. Mean values of measurements in knees with and without CMP and in knees with early and advanced stage CMP were compared.

RESULTS

We found CMP in 169 (58.7%) patients. Patients with CMP demonstrated a significantly greater sulcus angle (P = 0.012), smaller LTI (P = 0.004), greater PT (P = 0.01), smaller LPA (P = 0.036), greater Insall-Salvati ratio (P = 0.034), and higher incidence of SHFP edema (P = 0.001) compared to those without CMP. While none of the measurements were associated with the severity of cartilage damage, the incidence of SHFP edema was significantly correlated with the severity of CMP (P = 0.001).

CONCLUSION

CMP is a common disorder among military recruits with AKP. Patellofemoral malalignment is an important contributory factor in the development of CMP, and the presence of edema in SHFP may be a strong indicator of underlying severe CMP in this population.

Risk Factors Associated With Musculoskeletal Injury: A Prospective Study of British Infantry Recruits

Background:

Musculoskeletal Injury (MSKI), a common problem in both military and physically active civilian populations, has been suggested to result from both extrinsic and intrinsic factors.

Objective:

To investigate prospectively whether gait biomechanics, aerobic fitness levels and smoking status as well as entry military selection test variables can be used to predict MSKI development during recruit training.

Methods:

British infantry male recruits (n = 562) were selected for the study. Plantar pressure variables, smoking habit, aerobic fitness as measured by a 1.5 mile run time and initial military selection test (combination of fitness, Trainability score) were collected prior to commencement of infantry recruit training. Injury data were collected during the 26 week training period.

Results:

Incidence rate of MSKI over a 26 week training period was 41.28% (95 % CI: 37.28 - 45.40%). The injured group had a higher medial plantar pressure (p < 0.03), shorter time to peak heel rotation (p < 0.02), current smoking status (p < 0.001) and a slower 1.5 mile run time (p < 0.03). In contrast, there were no significant differences (p > 0.23) in lateral heel pressure, age, weight, height, BMI and military selection test. A logistic regression model predicted MSKI significantly (p= 0.03) with an accuracy of 34.50% of all MSK injury and 76.70% of the non-injured group with an overall accuracy of 69.50%.

Conclusion:

The logistic regression model combining the three risk factors was capable of predicting 34.5% of all MSKI. A specific biomechanical profile, slow 1.5 mile run time and current smoking status were identified as predictors of subsequent MSKI development. The proposed model could include evaluation of other potential risk factors and if validated then further enhance the specificity, sensitivity and applicability.

Risk factors for patellofemoral pain: a systematic review and meta-analysis

BACKGROUND

Patellofemoral pain (PFP) is a prevalent condition commencing at various points throughout life. We aimed to provide an evidence synthesis concerning predictive variables for PFP, to aid development of preventative interventions.

METHODS

We searched Medline, Web of Science and SCOPUS until February 2017 for prospective studies investigating at least one potential risk factor for future PFP. Two independent reviewers appraised methodological quality using the Newcastle-Ottawa Scale. We conducted meta-analysis where appropriate, with standardised mean differences (SMD) and risk ratios calculated for continuous and nominal scaled data.

RESULTS

This review included 18 studies involving 4818 participants, of whom 483 developed PFP (heterogeneous incidence 10%). Three distinct subgroups (military recruits, adolescents and recreational runners) were identified. Strong to moderate evidence indicated that age, height, weight, body mass index (BMI), body fat and Q angle were not risk factors for future PFP. Moderate evidence indicated that quadriceps weakness was a risk factor for future PFP in the military, especially when normalised by BMI (SMD -0.69, CI -1.02, -0.35). Moderate evidence indicated that hip weakness was not a risk factor for future PFP (multiple pooled SMDs, range -0.09 to -0.20), but in adolescents, moderate evidence indicated that increased hip abduction strength was a risk factor for future PFP (SMD 0.71, CI 0.39, 1.04).

CONCLUSIONS

This review identified multiple variables that did not predict future PFP, but quadriceps weakness in military recruits and higher hip strength in adolescents were risk factors for PFP. Identifying modifiable risk factors is an urgent priority to improve prevention and treatment outcomes.

Incidence and prevalence of patellofemoral pain: A systematic review and meta-analysis

BACKGROUND

Patellofemoral pain is considered one of the most common forms of knee pain, affecting adults, adolescents, and physically active populations. Inconsistencies in reported incidence and prevalence exist and in relation to the allocation of healthcare and research funding, there is a clear need to accurately understand the epidemiology of patellofemoral pain.

METHODS

An electronic database search was conducted, as well as grey literature databases, from inception to June 2017. Two authors independently selected studies, extracted data and appraised methodological quality. If heterogeneous, data were analysed descriptively. Where studies were homogeneous, data were pooled through a meta-analysis.

RESULTS

23 studies were included. Annual prevalence for patellofemoral pain in the general population was reported as 22.7%, and adolescents as 28.9%. Incidence rates in military recruits ranged from 9.7-571.4/1,000 person-years, amateur runners in the general population at 1080.5/1,000 person-years and adolescents amateur athletes 5.1%-14.9% over 1 season. One study reported point prevalence within military populations as 13.5%. The pooled estimate for point prevalence in adolescents was 7.2% (95% Confidence Interval: 6.3%-8.3%), and in female only adolescent athletes was 22.7% (95% Confidence Interval 17.4%-28.0%).

CONCLUSION

This review demonstrates high incidence and prevalence levels for patellofemoral pain. Within the context of this, and poor long term prognosis and high disability levels, PFP should be an urgent research priority.

PROSPERO REGISTRATION

CRD42016038870.

Comparison of ischemic compression and lumbopelvic manipulation as trigger point therapy for patellofemoral pain syndrome in young adults: A double-blind randomized clinical trial

OBJECTIVE

To compare the effectiveness of ischemic compression (IC) directly to the vastus medialis obliquus (VMO) versus lumbopelvic manipulation (LPM) in improving pain, functional status and sensitivity to mechanical stimulation of the VMO trigger point in patients with patellofemoral pain syndrome (PFPS).

PARTICIPANTS

40 patients with unilateral PFPS aged 20-30 years were selected randomly among patients with unilateral PFPS referred to physical therapy clinics of Shiraz University of Medical Sciences in Shiraz, Iran, between March 2014 and July 2014. 30 young adults participated. Participants were blinded to treatment allocation, and 15 patients were allocated to either IC or LPM.

INTERVENTIONS

Patients in both groups were treated in three sessions per week. IC consisted of three sets of continuous pressure applied for on the myofascial trigger point (MTrP) of VMO. LPM consisted of supine rotational glide manipulation of the ipsilateral lumbopelvic region of the involved knee.

MAIN OUTCOME MEASURES

Numeric pain rating scale (VAS) for pain intensity, Kujala questionnaire for functional status, and pressure pain threshold (PPT) for sensitivity to mechanical stimulation. All three were recorded before treatment, 1 week, 1 month and 3 months after the last session.

RESULTS

Both groups showed significant improvement (p < 0.05, 95% confidence interval) in pain, functional status and PPT values. However, the IC group showed greater improvements, and outcome measures remained significantly better than in the LPM group during post-intervention follow-up.

CONCLUSIONS

Both groups showed improvements throughout the study and follow-up period. However, the IC showed better short-term and long-term effectiveness than LPM for treating PFPS.

A randomised trial into the effect of an isolated hip abductor strengthening programme and a functional motor control programme on knee kinematics and hip muscle strength

Background

Dynamic knee valgus and internal femoral rotation are proposed to be contributory risk factors for patellofemoral pain and anterior cruciate ligament injuries. Multimodal interventions including hip abductor strengthening or functional motor control programmes have a positive impact of pain, however their effect on knee kinematics and muscle strength is less clear. The aim of this study was to examine the effect of isolated hip abductor strengthening and a functional motor control exercise on knee kinematics and hip abductor strength.

Methods

This prospective, randomised, repeated measures design included 29 asymptomatic volunteers presenting with increase knee valgus and femoral internal rotation. Participants completed either isolated hip abductor strengthening or a functional motor control exercise for 5 weeks. Knee kinematics were measured using inertial sensors during 2 functional activities and hip abductor strength measured using a load cell during isometric hip abduction.

Results

There were no significant differences in dynamic knee valgus and internal rotation following the isolated hip abductor or functional motor control intervention, and no significant differences between the groups for knee angles. Despite this, the actual magnitude of reduction in valgus was 10° and 5° for the functional motor control group and strengthening group respectively. The actual magnitude of reduction in internal rotation was 9° and 18° for the functional motor control group and strengthening group respectively. Therefore there was a tendency towards clinically significant improvements in knee kinematics in both exercise groups. A statistically significant improvement in hip abductor strength was evident for the functional motor control group (27% increase; p = 0.008) and strengthening group (35% increase; p = 0.009) with no significant difference between the groups being identified (p = 0.475).

Conclusions

Isolated hip strengthening and functional motor control exercises resulted in non-statistically significant changes in knee kinematics, however there was a clear trend towards clinically meaningful reductions in valgus and internal rotation. Both groups demonstrated similar significant gains in hip abductor strength suggesting either approach could be used to strengthen the hip abductors.

Lumbopelvic manipulation in patients with patellofemoral pain syndrome

OBJECTIVES

A recent clinical prediction rule (CPR) identified characteristics that may predict an immediate reduction in pain following lumbopelvic manipulation in patients with patellofemoral pain syndrome. The purpose of this single-arm cohort study was to replicate the proposed CPR in a different population and investigate changes in self-reported pain, hip range of motion, strength, and function immediately following lumbopelvic manipulation.

METHODS

Forty-four subjects (63·6% female; mean age 27·4 years) met inclusion criteria. Hip internal rotation range of motion, lower extremity strength using a handheld dynamometer, and single/triple hop tests were assessed prior to and immediately following a spinal manipulation. A global rating of change questionnaire was administered after testing and telephonically at 1 week. Paired t-tests compared pre- and post-manipulation range of motion, strength, and hop test limb symmetry indices (α = 0·05).

RESULTS

Fifty-seven percent of subjects had a successful outcome measured by the numerical pain rating scale immediately following manipulation. Twenty-five of subjects experienced a successful outcome as measured by the global rating of change questionnaire at 1 week. No single individual or combination of predictor variables predicted a positive outcome immediately following the lumbopelvic manipulation (+likelihood ratio 0·7 with three of five predictor variables present). Statistically significant differences (P<0·05) were found in hip extension and abduction strength and hip internal rotation symmetry post-manipulation, but do not appear to be clinically meaningful.

DISCUSSION

The previously identified CPR was not able to be replicated and no clinically meaningful changes in range of motion, strength, or function were apparent. Future research should focus on a comprehensive impairment-based treatment approach in patients with patellofemoral pain syndrome.

Clinical test for diagnosis of patellofemoral pain syndrome: Systematic review with meta-analysis

The high incidence and diversity of factors attributed to the etiology of patellofemoral pain syndrome (PFPS) makes the diagnosis of this problem somewhat complex and susceptible to misinterpretation. Currently, there is not a defined set of procedures considered as ideal to diagnose PFPS. To investigate the diagnostic accuracy of clinical and functional tests used to diagnose PFPS through a systematic review. We searched relevant studies in the databases Medline, CINAHL, SPORTDiscus and Embase. The QUADAS score was used to assess the methodological quality of the eligible studies. We analyzed data that indicated the diagnostic properties of tests, such as sensibility, specificity, positive (LR+) and negative (LR-) likelihood ratio, and predictive values. The search identified 16,169 potential studies and five studies met the eligibility criteria. The 5 studies analyzed 25 tests intending to accurately diagnose PFPS. Two tests were analyzed in two studies and were possible to perform a meta-analysis. Within the five studies included, one study had high methodological quality, two studies had good methodological quality and two studies had low methodological quality. Two tests, the patellar tilt (LR+ = 5.4 and LR- = 0.6) and squatting (LR+ = 1.8 and LR- = 0.2), had values that show a trend for the diagnosis of PFPS (LR+ >5.0 and LR- <0.2), however their values do not represent clear evidence regarding diagnostic properties as suggested in the literature (LR+ >10 and LR- <0.1). Future diagnostic studies should focus on the sample homogeneity and standardization of tests analyzed so future systematic reviews can determine with more certainty the accuracy of the tests for diagnosis of PFPS.

The effects of exercise for the prevention of overuse anterior knee pain: a randomized controlled trial

BACKGROUND

Anterior knee pain (AKP) is the most common activity-related injury of the knee. The authors investigated the effect of an exercise intervention on the incidence of AKP in UK army recruits undergoing a 14-week physically arduous training program.

HYPOTHESIS

Modifying military training to include targeted preventative exercises may reduce the incidence of AKP in a young recruit population.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A single-blind cluster randomized controlled trial was performed in 39 male and 11 female training groups (median age: 19.7 years; interquartile range, 17-25) undergoing phase 1 of army recruit training. Each group was randomly assigned to either an intervention (n = 759) or control (n = 743) protocol. The intervention consisted of 4 strengthening and 4 stretching exercises completed during supervised physical training lessons (7 per week). The control group followed the existing training syllabus warm-up exercises. The primary outcome was a diagnosis of AKP during the 14-week training program.

RESULTS

Forty-six participants (3.1%; 95% confidence interval [CI], 2.3-4.1) were diagnosed with AKP. There were 36 (4.8%; 95%CI, 3.5-6.7) new cases of AKP in the control group and 10 (1.3%; 0.7-2.4) in the intervention group. There was a 75% reduction in AKP risk in the intervention group (unadjusted hazard ratio = 0.25; 95% CI, 0.13-0.52; P < .001). Three participants (0.4%) from the intervention group were discharged from the military for medical reasons compared to 25 (3.4%) in the control group.

CONCLUSION

A simple set of lower limb stretching and strengthening exercises resulted in a substantial and safe reduction in the incidence of AKP in a young military population undertaking a physical conditioning program. Such exercises could also be beneficial for preventing this common injury among nonmilitary participants in recreational physical activity.

Performance on the single-leg squat task indicates hip abductor muscle function

BACKGROUND

Contemporary clinical expertise and emerging research in anterior knee pain indicate that treatment of hip muscle function will result in greater effects, if such treatments can be provided to those with hip muscle dysfunction. Thus, it is imperative to develop and evaluate a clinical assessment tool that is capable of identifying people with poor hip muscle function.

HYPOTHESIS

The clinical assessment of single-leg squat performance will have acceptable inter- and intrarater reliability. Furthermore, people with good performance on the single-leg squat will have better hip muscle function (earlier onset of gluteus medius activity and greater lateral trunk, hip abduction, and external rotation strength) than people with poor performance.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

A consensus panel of 5 experienced clinicians developed criteria to rate the performance of a single-leg squat task as "good," "fair," or "poor." The panel rated the performance of 34 asymptomatic participants (mean ± SD: age, 24 ± 5 y; height, 1.69 ± 0.10 m; weight, 65.0 ± 10.7 kg), and these ratings served as the standard. The ratings of 3 different clinicians were compared with those of the consensus panel ratings (interrater reliability) and to their own rating on 2 occasions (intrarater reliability). For the participants rated as good performers (n = 9) and poor performers (n = 12), hip muscle strength (hip abduction, external rotation, and trunk side bridge) and onset timing of anterior (AGM) and posterior gluteus medius (PGM) electromyographic activity were compared.

RESULTS

Concurrency with the consensus panel was excellent to substantial for the 3 raters (agreement 87%-73%; κ = 0.800-0.600). Similarly, intrarater agreement was excellent to substantial (agreement 87%-73%; κ = 0.800-0.613). Participants rated as good performers had significantly earlier onset timing of AGM (mean difference, -152; 95% confidence interval [CI], -258 to -48 ms) and PGM (mean difference, -115; 95% CI, -227 to -3 ms) electromyographic activity than those who were rated as poor performers. The good performers also exhibited greater hip abduction torque (mean difference, 0.47; 95% CI, 0.10-0.83 N·m·Bw(-1)) and trunk side flexion force (mean difference, 1.08; 95% CI, 0.25-1.91 N·Bw(-1)). There was no difference in hip external rotation torque (P > .05) between the 2 groups.

CONCLUSION

Targeted treatments, although considered ideal, rely on the capacity to identify subgroups of people with chronic anterior knee pain who might respond optimally to a given treatment component. Clinical assessment of performance on the single-leg squat task is a reliable tool that may be used to identify people with hip muscle dysfunction.

Gender differences in the incidence and prevalence of patellofemoral pain syndrome

The purpose of this investigation was to determine the association between gender and the prevalence and incidence of patellofemoral pain syndrome (PFPS). One thousand five hundred and twenty-five participants from the United States Naval Academy (USNA) were followed for up to 2.5 years for the development of PFPS. Physicians and certified athletic trainers documented the cases of PFPS. PFPS was defined as retropatellar pain during at least two of the following activities: ascending/descending stairs, hopping/jogging, prolonged sitting, kneeling, and squatting, negative findings on examination of knee ligament, menisci, bursa, and synovial plica, and pain on palpation of either the patellar facets or femoral condyles. Poisson and logistic regressions were performed to determine the association between gender and the incidence and prevalence of PFPS, respectively. The incidence rate for PFPS was 22/1000 person-years. Females were 2.23 times (95% CI: 1.19, 4.20) more likely to develop PFPS compared with males. While not statistically significant, the prevalence of PFPS at study enrollment tended to be higher in females (15%) than in males (12%) (P=0.09). Females at the USNA are significantly more likely to develop PFPS than males. Additionally, at the time of admission to the academy, the prevalence of PFPS was not significantly different between genders.

Predictors of short and long term outcome in patellofemoral pain syndrome: a prospective longitudinal study

Background

Patellofemoral pain syndrome (PFP) is a common musculoskeletal condition that has a tendency to become chronic and problematic in a proportion of affected individuals. The objective of this study was to identify prognostic factors that may have clinical utility in predicting poor outcome on measures of pain and function in individuals with PFP.

Methods

A prospective follow-up study was conducted of 179 participants in a randomised clinical trial. Nine baseline factors (age, gender, body mass index, arch height, duration of knee pain, worst pain visual analogue scale, Kujala Patellofemoral Score (KPS), functional index questionnaire (FIQ), step down repetitions) were investigated for their prognostic ability on outcome assessed at six, 12 and 52 weeks (worst pain, KPS and FIQ). Factors with significant univariate associations were entered into multivariate linear regression models to identify a group of factors independently associated with poor outcome.

Results

Long symptom duration was the most consistent predictor of poor outcome over 52 weeks rated on the KPS and the FIQ (β-0.07, 95% confidence interval -0.1 to -0.03, p < 0.000; and -0.02, -0.03 to -0.01, p < 0.000, respectively). Worse KPS at baseline was predictive of outcome at six, 12 and 52 weeks. Gender, body mass index and arch height were generally not associated with outcome (univariate analysis), while age, worst pain, FIQ and step downs were excluded during multivariate analyses.

Conclusions

Patients presenting with PFP of long duration who score worse on the KPS have a poorer prognosis, irrespective of age, gender and morphometry. These results suggest that strategies aimed at preventing chronicity of more severe PFP may optimise prognosis.

Gonalgia entre trabalhadores e fatores ocupacionais associados: uma revisão sistemática

Com o objetivo de reunir informações sobre gonalgia entre trabalhadores e fatores ocupacionais associados, foi realizada uma revisão sistemática nas bases de dados MEDLINE, LILACS, SciELO, Free Medical Journals, entre outros, referentes ao período 1990-2006, usando-se os descritores gonalgia, knee, knee pain, knee joint, knee dislocation, knee injuries, work, workplace, workload, employment, occupations, industry, occupational, workers, arthrosis, osteoarthritis e seus equivalentes em português e espanhol. Dos 2.263 estudos inicialmente encontrados, somente 26 cumpriram os critérios necessários para permanecer na revisão. As prevalências de gonalgia nos últimos 12 meses variaram entre 11,2% e 60,9%, e os principais fatores associados foram: sexo feminino, idade avançada, índice de massa corporal elevado, trabalhar ajoelhado e carregar peso no trabalho.