Intrinsic Risk Factors for the Development of Anterior Knee Pain in an Athletic Population: A Two-Year Prospective Study * Diagnostic accuracy and association to disability of clinical test findings associated with patellofemoral pain syndrome. Patellofemoral Pain Syndrome: Evaluation of Location and Intensity of Pain Early post-operative morbidity following anterior cruciate ligament reconstruction: patellar tendon versus hamstring graft Comparison of symptoms and clinical findings in subgroups of individuals with patellofemoral pain A systematic review of the effects of therapeutic taping on patellofemoral pain syndrome. Gait metric profile of 157 patients suffering from anterior knee pain. A controlled study. The natural history of anterior knee pain in 2 posterior-stabilized, modular total knee arthroplasty designs. Patellar Tracking and Anterior Knee Pain are Similar After Medial Parapatellar and Midvastus Approaches in Minimally Invasive TKA Analysis of outcome measures for persons with patellofemoral pain: which are reliable and valid? Factors that predict a poor outcome 5–8 years after the diagnosis of patellofemoral pain: a multicentre observational analysis A Prospective Investigation of Biomechanical Risk Factors for Patellofemoral Pain Syndrome The effects of patellar taping on pain and neuromuscular performance in subjects with patellofemoral pain syndrome ACTIVATION OF VASTUS MEDIALIS OBLIQUUS AMONG INDIVIDUALS WITH PATELLOFEMORAL PAIN SYNDROME Patellofemoral Pain Syndrome: Validity of Clinical and Radiological Features The effect of patellar taping on EMG activity of vasti muscles during squatting in individuals with patellofemoral pain syndrome The Effects of Exercise for the Prevention of Overuse Anterior Knee Pain
Many variables have retrospectively been associated with the presence of anterior knee pain . Very few prospect i ve data exist , however , to determine which of these variables will lead to the development of anterior knee pain . It was our purpose in this study to determine the intrinsic risk factors for the development of anterior knee pain in an athletic population over a 2-year period . Before the start of training , 282 male and female students enrolled in physical education classes  were evaluated for anthropometric variables , motor performance , general joint laxity , lower leg alignment characteristics , muscle length and strength , static and dynamic patellofemoral characteristics , and psychological parameters . During this 2-year follow-up study , 24 of the 282 students developed  patellofemoral pain . Statistical analyses revealed a significant difference between those subjects who developed patellofemoral pain and those who did not concerning quadriceps and gastrocnemius muscle flexibility , explosive strength , thumb-forearm mobility , reflex response time of the vastus medialis obliquus and vastus lateralis muscles , and the psychological parameter of seeking social support . However , only a shortened quadriceps muscle , an altered vastus medialis obliquus muscle reflex response time , a decreased explosive strength , and a hypermobile patella had a significant correlation with the incidence of patellofemoral pain . We concluded that the latter four parameters play a dominant role in the genesis of anterior knee pain and we therefore deem them to be risk factors for this syndrome PURPOSE To investigate the diagnostic accuracy and association to disability of selected functional findings or physical examination tests for patellofemoral pain syndrome ( PFPS ) in patients with anterior knee pain . METHODS A sample of 76 consecutive patients with anterior knee pain was further subdivided into PFPS and other diagnoses . Routine physical examination tests were examined in a prospect i ve , consecutive-subjects design for a cohort of patients with anterior knee pain . Diagnostic accuracy findings , including sensitivity , specificity , positive ( PPV ) and negative ( NPV ) predictive value , and positive ( LR+ ) and negative ( LR- ) likelihood ratios , were calculated for each test . PPV and NPV reflect the percentage of time of positive or a negative test ( respectively ) accurately captures the diagnosis of the condition . LR+ and LR- reflect alterations in post-test probability when the test is positive or negative ( respectively ) . Lastly , associations to disability ( International Knee Documentation Committee ( IKDC ) subjective form ) were calculated for each clinical finding . RESULTS Diagnostic accuracy analyses of individual functional assessment and situational phenomena suggest that the strongest diagnostic test is pain encountered during resisted muscle contraction of the knee ( PPV=82 % ; LR+=2.2 ; 95 % CI : 0.99 - 5.2 ) . Clusters of test findings were substantially more diagnostic , with any two of three positive findings of muscle contraction , pain during squatting , and pain during palpation yielding the following values : PPV=89 % ; LR+=4.0 ( 95 % CI : 1.8 - 10.3 ) . No individual or clustered test findings were significantly associated with the IKDC score . CONCLUSION Combinations of functional assessment tests and situational phenomena are diagnostic for PFPS and may serve to rule in and rule out the presence of PFPS . Single findings are not related to disability scores ( IKDC ) Objectives : To identify the sites and intensity of pain in patients with patellofemoral pain syndrome . Method : A prospect i ve cohort study was conducted at an academic sports medicine practice in Boston , Massachusetts . All patients met inclusion criteria and were enrolled and evaluated during the study time frame . A single sports medicine orthopaedic surgeon examined a consecutive sample of patients with patellofemoral pain not explained by one of several well-defined anterior knee pain diagnoses . The study group consisted of 100 patients ( 75 females , 25 males ) with median age of 14 years . Eleven discrete locations were palpated for tenderness .  Hamstring tightness  was evaluated by measuring the popliteal angle . Patients reported intensity of pain using a 0- to 9-point ordinal scale . Regression and nonparametric statistical methods were used . Results : The most common site of pain was the patella during anterior-posterior compression ( 90 patients ) , followed by the distal pole of the patella , the medial plica , and the nonarticular medial femoral condyle . Median “ worst pain ” intensity was 6 out of a possible 9 . The most common site of “ worst pain ” was also the patella in compression ( 63 patients ) . Median duration of symptoms was 10 months , with an interquartile range of 3 to 20 months . Pain intensity was inversely correlated with duration of symptoms ( P < 0.01 ) . Conclusions : In these patients with patellofemoral pain syndrome , the major source of pain was the patella subchondral bone Abstract . This study documented postoperative morbidity during the first 4 months following  anterior cruciate ligament ( ACL ) reconstruction  using either patellar tendon or hamstring tendon autograft .  Sixty-five patients undergoing primary arthroscopically assisted single-incision ACL reconstruction  were r and omized to have a central third bone patellar tendon bone autograft ( PT ) or a doubled semitendinosus/doubled gracilis autograft ( HS ) . Postoperatively patients undertook a st and ard ' accelerated ' rehabilitation protocol . Patients were review ed after 2 weeks , 8 weeks , and 4 months . At each review the location and severity of general knee pain and the presence and severity of anterior knee pain ( AKP ) were recorded as were the presence and size of an effusion as well as the active and passive flexion and passive extension deficits compared to the contralateral limb . Pain on kneeling , KT-1000 measured side to side difference in anterior tibial displacement , isokinetic assessment of quadriceps and hamstring peak torque deficits , IKDC score and Cincinnati sports activity level were also recorded after 4 months . After 2 weeks more patients in the PT group complained of AKP and reported that the pain was more severe . After 8 weeks there was no significant difference between the groups for any variable . After 4 months the severity of general pain experienced and the incidence of pain on kneeling were greater in the PT group . The PT group also demonstrated a significantly greater quadriceps peak torque deficit at 240 ° /s . IKDC scores were higher in the HS group , but Cincinnati sports activity scores were higher in the PT group . Although we observed a lower morbidity in the HS group , primarily related to pain , the severity of pain in both groups was relatively low and , in light of the higher mean sports activity level observed in the PT group at 4 months the clinical impact of the difference may not be significant Patellofemoral pain syndrome ( PFPS ) is one of the most common musculoskeletal disorders . However , no consensus on the definition , classification , assessment , diagnosis , or management has been reached . We evaluated symptoms and clinical findings in subgroups of individuals with PFPS , classified on the basis of the findings in radiological examinations and compared the findings with knee-healthy subjects . An orthopedic surgeon and a physical therapist consecutively examined 80 patients clinical ly diagnosed as having PFPS and referred for physical therapy .  The examination consisted of taking a case history and clinical tests . Radiography revealed pathology in 15 patients , and scintigraphic examination revealed focal uptake in 2 patients indicating pathology ( group C ) . Diffusely increased uptake was present in 29 patients ( group B ) . In the remaining 29 patients radiographic and scintigraphic examinations were normal ( group A ) . Knee-healthy controls ( group D ) reported no clinical symptoms . No symptom could be statistically demonstrated to differ between the three patient groups . Knee-healthy subjects differed significantly from the three patient groups in all clinical tests measuring pain in response to the provocations ; compression test , medial and lateral tenderness , passive gliding of the patella , but they also differed in Q angle . Differences in clinical tests between the patient groups were nonsignificant . The main finding in our study on patients clinical ly diagnosed with PFPS is that possible pathologies can not be detected from the patient 's history or from commonly used clinical tests OBJECTIVE To investigate the efficacy of patellar taping on pain control , patellar alignment , and neuromuscular control ( ie , vastus medialis oblique activation , knee extensor moment , etc ) in subjects with patellofemoral pain syndrome . DATA SOURCES We search ed MEDLINE , SPORT Discus , PEDro , and CINAHL through December 2004 , using the key words patellar taping , therapeutic taping , McConnell taping , taping , chronic injury , patellofemoral pain , and knee . STUDY SELECTION Criteria for inclusion criteria were studies that exclusively recruited patients diagnosed with patellofemoral pain syndrome or anterior knee pain and outcome measures specific to pain reduction , neuromuscular control , and patellar positioning . DATA EXTRACTION We identified and review ed 16 studies with an average PEDro score of 4.25/10 . Articles were divided into 3 categories based on primary outcome measures : 4 r and omized controlled trials on treatment methods and pain , 9 studies on neuromuscular control , and 3 on patellar positioning . DATA SYNTHESIS Although patellar taping seems to reduce pain and improve function in people with patellofemoral pain syndrome during activities of daily living and rehabilitation exercise , strong evidence to identify the underlying mechanisms is still not available PURPOSE Gait metric alterations have been previously reported in patients suffering from anterior knee pain ( AKP ) . Characterization of simple and measureable gait parameters in these patients may be valuable for assessing disease severity as well as for follow-up . Previous gait studies in this population have been comprised of relatively small cohorts and the findings of these studies are not uniform . The objective of the present study was to examine spatio-temporal gait parameters in patients with AKP in comparison to symptom-free controls . Furthermore , the study aim ed to examine the relationship between self-reported disease severity and the magnitude of gait abnormalities . METHODS 157 patients with AKP were identified and compared to 31 healthy controls . Patients were evaluated with a spatiotemporal gait analysis via a computerized mat , the Western Ontario and McMaster Osteoarthritis Index ( WOMAC )  question naire and the Short Form (SF)-36 health surveys . RESULTS AKP patients walked with significantly lower velocity ( 15.9 % ) and cadence ( 5.9 % ) , shorter step length ( 9.5 % ) , stride length ( 9.6 % ) , and showed significant differences in all gait cycle phases ( P<0.05 for all ) . Study group reported higher levels of pain ( 96 % ) , functional limitation ( 94 % ) , and poorer perception of mental quality of life ( 30 % ) ( P<0.05 for all ) . CONCLUSION Significant differences were found between the spatiotemporal gait profile of AKP patients and symptom-free matched controls . In addition , an association was found between subjective disease severity and gait abnormalities . These findings suggest the usefulness of gait parameters , alongside with the use of self-evaluation question naires , in identifying deviations of these patients from healthy population Anterior knee pain ( AKP ) has been a persistent complaint after total knee arthroplasty ; however , the natural course of this complaint has not been fully investigated . This is a 10-year follow-up report of a prospect i ve , r and omized study between the Insall-Burstein II ( Zimmer , Warsaw , IN ) and the Press Fit Condylar Modular ( Johnson & Johnson , Raynham , MA ) knees . Up to one third of total knee arthroplasties will experience mild to moderate AKP at 1-year follow-up , which will persist in approximately 30 % of these previously symptomatic knees at 10-year follow-up . New-onset AKP will develop in approximately 10 % of previously asymptomatic knees Background Since the medial parapatellar ( MPP ) approach in conventional TKA can cause patellar maltracking and anterior knee pain , some orthopaedic surgeons use the midvastus ( MV ) approach instead of the MPP approach to reduce patellar maltracking . Minimally invasive surgical ( MIS ) TKA has been developed to limit the damage to the surrounding muscle and reduce the necessity of patellar eversion during surgery . Thus , MIS TKA might be associated with proper patellar tracking and a low incidence of anterior knee pain . However , this presumption has not been confirmed . Questions / purpose sWe asked whether the incidence of patellar maltracking and anterior knee pain differed with the MV and MPP in association with MIS TKA . Methods We prospect ively followed 59 patients ( 60 knees ) treated with 60 primary cemented MIS TKAs from August 2009 to September 2010 . We r and omized the patients into two groups : 30 who had a limited MPP approach and 30 who had a mini-MV approach . We recorded the occurrence of anterior knee pain , patellar tilting , and subluxation . The minimum followup was 12 months ( mean , 18.03 months ; range , 12.00–25.08 months ) . Results We found no differences in anterior knee pain ( two of 30 , 7 % versus two of 30 , 7 % ) , mean patellar tilt ( 3.4º ± 2.9º versus 3.0 ± 2.3º ) , and mean patellar subluxation ( 1.5 ± 1.1 mm versus 1.1 ± 0.7 mm ) between the limited MPP and mini-MV groups , respectively . Conclusions MIS TKA using either the MPP or MV approach has a low incidence of patellar maltracking and anterior knee pain . Level of Evidence Level I , therapeutic study . See the Guidelines for Authors for a complete description of the levels of evidence OBJECTIVE To examine the test-retest reliability , validity , and responsiveness of several outcome measures in the treatment of patellofemoral pain . DESIGN Evaluation of the clinimetric properties of individual outcome measures for patellofemoral pain treatment , using data collected from a previously published r and omized controlled trial ( RCT ) . SETTING General community and private practice . PARTICIPANTS The data from 71 persons enrolled in an RCT of a conservative intervention for patellofemoral pain were used to evaluate the measures ' validity and responsiveness . A subset of this cohort ( n=20 ) was used to assess reliability . INTERVENTIONS Not applicable . MAIN OUTCOME MEASURES Three  10-cm visual analog scales ( VASs ) for usual pain ( VAS-U ) , worst pain ( VAS-W ) , and pain on 6 aggravating activities ( walking , running , squatting , sitting , ascending and descending stairs ) ( VAS-activity ) ; the Functional Index Question naire ( FIQ ) ; the Anterior Knee Pain Scale ( AKPS ) ; and the global rating of change . RESULTS The test-retest reliability ranged from poor ( intraclass correlation coefficient [ICC]=.49 ) to good ( ICC=.83 ) , and the measures correlated moderately with each other ( r range,.56-.72 ) . Median change scores differed significantly between improved and unimproved persons for all measures . The effect sizes for VAS-U ( .79 ) , VAS-W ( .88 ) , and the AKPS ( .98 ) were large , indicating greater responsiveness than the FIQ ( .37 ) and VAS-activity ( .66 ) . Similarly , the AKPS and VAS-W were the most efficient measures for detecting a treatment effect when compared with a reference measure ( VAS-U , which was assigned a value of 1 ) . The minimal difference that patients or clinicians consider clinical ly important for the AKPS is 10 ( out of 100 ) points and for the VAS it is 2 cm ( out of 10 cm ) . CONCLUSIONS The AKPS and VAS for usual or worst pain are reliable , valid , and responsive and are therefore recommended for future clinical trials or clinical practice in assessing treatment outcome in persons with patellofemoral pain Background Patellofemoral pain ( PFP ) has traditionally been viewed as self-limiting , but recent studies show that a large proportion of patients report chronic knee pain at long-term follow-up . We identified those patients with an unfavourable recovery ( ‘ moderate improvement ’ to ‘ worse than ever ’ measured on a Likert scale ) and examined whether there is an association between PFP and osteoarthritis ( OA ) at 5–8-year follow-up . Methods Long-term follow-up data were derived from 2 r and omised controlled trials ( n=179 , n=131 ) .  Patient-reported measures were obtained at baseline .  Pain severity ( 100 mm visual analogue scale ( VAS ) ) , function ( Anterior Knee Pain Scale ( AKPS ) ) and self-reported recovery were measured 5–8 years later , along with knee radiographs . Multivariate backward stepwise linear regression analyses were used to evaluate the prognostic ability of baseline pain duration , pain VAS and AKPS on outcomes of pain VAS and AKPS at 5–8 years . Results 60 ( 19.3 % ) participants completed the question naires at 5–8-year follow-up ( 45 women , mean age at baseline 26 years ) and 50 underwent knee radiographs . No differences were observed between responders and non-responders regarding baseline demographics , and 3-month and 12-month pain severity and recovery . 34 ( 57 % ) reported unfavourable recovery at 5–8 years . 48 out of 50 participants ( 98 % ) had no signs of radiographic knee OA . Multivariate models revealed that baseline PFP duration ( > 12 months ; R2=0.22 ) and lower AKPS ( R2=0.196 ) were significant predictors of poor prognosis at 5–8 years on measures of worst pain VAS and AKPS , respectively . Summary and conclusion More than half of participants with PFP reported an unfavourable recovery 5–8 years after recruitment , but did not have radiographic knee OA . Longer PFP duration and worse AKPS score at baseline predict poor PFP prognosis . Education of health practitioners and the general public will provide patients with more realistic expectations regarding prognosis Background Patellofemoral pain syndrome is one of the most common chronic knee injuries ; however , little research has been done to determine the risk factors for this injury . Hypothesis Altered lower extremity kinematics and kinetics , decreased strength , and altered postural measurements will be risk factors . Study Design Cohort study ( prognosis ) ; Level of evidence , 2 . Methods A total of 1597 participants were enrolled in this investigation and prospect ively followed from the date of their enrollment ( July 2005 , July 2006 , or July 2007 ) through January 2008 , a maximum of 2.5 years of follow-up . Each participant underwent baseline data collection during their pre-freshman summer at the United States Naval Academy . Baseline data collection included 3-dimensional motion analysis during a jump-l and ing task , 6 lower extremity isometric strength tests , and postural alignment measurements ( navicular drop and Q angle ) . Results Risk factors for the development of patellofemoral pain syndrome included decreased knee flexion angle , decreased vertical ground-reaction force , and increased hip internal rotation angle during the jump-l and ing task . Additionally , decreased quadriceps and hamstring strength , increased hip external rotator strength , and increased navicular drop were risk factors for the development of patellofemoral pain syndrome . Conclusion Multiple modifiable risk factors for patellofemoral pain syndrome pain have been identified in this investigation . To decrease the incidence of this chronic injury , the risk factors for patellofemoral pain syndrome need to be targeted in injury prevention programs . Clinical Relevance Prevention programs should focus on increasing strength of the lower extremity musculature along with instructing proper mechanics during dynamic movements to decrease the incidence of patellofemoral pain syndrome Objective : To examine the immediate effects of patellar taping on pain and relative activity of vastus medialis obliquus to vastus lateralis in subjects with patellofemoral pain and patellofemoral joint malalignment . Design : Pre- and post-treatment design , with order of testing determined r and omly . Setting : Outpatient physiotherapy department . Subjects : Fifteen subjects with patellofemoral joint pain and malalignment . Interventions : With and without patellar taping with a st and ard force of application . Main outcome measures : Pain and surface EMG activity ratio of vastus medialis obliquus to vastus lateralis during single-legged semi-squat with 20 % of extra body weight loading . Results : There was a significant decrease in anterior knee pain ( p < 0.001 ) and vastus medialis obliquus to vastus lateralis activity ratio ( p = 0.05 ) during single-legged st and ing after patellar taping . Conclusions : Patellar taping can reduce pain in people with patellofemoral pain syndrome and patellofemoral malalignment but it decreases the relative activity of vastus medialis obliquus to vastus lateralis . Such a decrease in relative activity of vastus medialis obliquus after taping implies that it may not be suitable to combine patellar taping with vastus medialis obliquus facilitative exercise training The purpose of this study was to determine whether various positions of the lower extremity affect the muscle activity of the vastus medialis obliquus ( VMO ) differently during both open and closed kinetic chain exercise conditions among patients with patellofemoral pain syndrome ( PFPS ) . Patients who presented with symptoms consistent with PFPS completed a series of open kinetic chain and closed kinetic chain exercises in which  VMO activity was measured and compared . Statistical analysis revealed that there is less than a 0.001 % ( open kinetic chain ) or 0.005 % ( closed kinetic chain ) chance that all positions activate the VMO equally . In open kinetic exercise , maximum VMO activity was achieved with terminal knee extension with medial tibial rotation . During closed kinetic exercises , squats with external rotation were preferred for maximum VMO activation . Therefore , our results highlight the importance of including both the open and closed kinetic chain exercises into rehabilitation programs for patients with PFPS Data regarding validity of clinical and radiographic findings in diagnosing patellofemoral pain syndrome are inconclusive . We prospect ively assessed how sensitive and specific key patellofemoral physical examination tests are , and evaluated the prevalence of physical examination and radiographic findings . Sixty-one infantry soldiers with patellofemoral pain syndrome and 25 control subjects were evaluated . The sensitivity of the patellar tilt , active instability , patella alta , and apprehension tests was low ( less than 50 % ) ; specificity ranged between 72 % and 100 % . Although the prevalence of positive patellar tilt and active instability tests was significantly greater in subjects with patellofemoral pain syndrome , there were no significant differences between the groups in the results of the other two tests . Soldiers with patellofemoral pain syndrome presented with increased quadriceps angle , lateral and medial retinacular tenderness , patellofemoral crepitation , squinting patella , and reduced mobility of the patella . There were no differences between the groups in the prevalence of lower limb and foot posture alignment and knee effusion .  Plain radiography showed increased patellar subluxation in soldiers with patellofemoral pain syndrome . Other radiographic measures ( sulcus angle , Laurin angle , Merchant angle , and Insall-Salvati index ) were similar in both groups . We provide evidence regarding the validity of clinical and radiographic features commonly used for diagnosing patellofemoral pain syndrome . Physical examinations were more useful than plain radiography . Level of Evidence : Diagnostic study , Level I. See the Guidelines for Authors for a complete description of levels of evidence Abstract Although patellar taping has been shown to reduce pain in participants with patellofemoral pain syndrome , the mechanisms of pain reduction have not completely been established following its application . The purpose of this study was to evaluate EMG activity of vastus medialis and vastus lateralis following the application of patellar taping during a functional single leg squat . Both vastus medialis obliquus – vastus lateralis onset and vastus medialis obliquus/vastus lateralis amplitude of 18 participants with patellofemoral pain syndrome and 18 healthy participants as controls were measured using an EMG unit . This procedure was performed on the affected knee of participants with patellofemoral pain syndrome , before , during , and after patellar taping during unilateral squatting . The same procedure was also performed on the unaffected knees of both groups . The mean values of vastus medialis obliquus – vastus lateralis onset prior to taping ( 2.54 ms , s = 4.35 ) were decreased significantly following an immediate application of tape ( −3.22 ms , s = 3.45 ) and after a prolonged period of taping ( −6.00 ms , s = 3.40 s ) ( P < 0.05 ) . There was also a significant difference between the mean values of vastus medialis obliquus – vastus lateralis onset among controls ( −2.03 ms , s = 6.04 ) and participants with patellofemoral pain syndrome prior to taping ( P < 0.05 ) . However , there were no significant difference between the ranked values of vastus medialis obliquus/vastus lateralis amplitude of the affected and unaffected knees of participants with patellofemoral pain syndrome and controls during different conditions of taping ( P > 0.05 ) . Decreased values of vastus medialis obliquus – vastus lateralis onset may contribute to patellar realignment and explain the mechanism of pain reduction following patellar taping in participants with patellofemoral pain syndrome 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 : R and omized controlled trial ; Level of evidence , 1 . Methods : A single-blind cluster r and omized 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 r and omly 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 result ed 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
Of the functional tests , squatting demonstrated the highest sensitivity .
Other useful tests include pain during stair climbing and prolonged sitting .
Conclusion A diagnostic checklist is useful as it provides a structured method for diagnosing AKP in a clinical setting .
Background  Anterior knee pain ( AKP ) or patellofemoral pain syndrome is common and may limit an individual 's ability to perform common activities of daily living such as stair climbing and prolonged sitting .
The diagnosis is difficult as there are multiple definitions for this disorder and there are no accepted criteria for diagnosis .
It is therefore most commonly a diagnosis that is made once other pathologies have been excluded .
Objectives The aim of this study was to create an evidence -based checklist for research ers and clinicians to use for the diagnosis of AKP .