BACKGROUND: Delayed onset of vastus medialis (VM) activity compared with vastus lateralis activity is a reported cause for patellofemoral pain. The delayed onset of VM activity in patellofemoral pain patients likely causes an imbalance in muscle forces and lateral maltracking of the patella; however, evidence relating VM activation delay to patellar maltracking is sparse. The aim of this study was to investigate the relationship between VM activation delay and patellar maltracking measures in pain-free controls and patellofemoral pain patients. HYPOTHESIS: Patellar tilt and bisect offset, measures of patellar tracking, correlate with VM activation delay in patellofemoral pain patients classified as maltrackers. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: Vasti muscle activations were recorded in pain-free (n = 15) and patellofemoral pain (n = 40) participants during walking and jogging. All participants were scanned in an open-configuration magnetic resonance scanner in an upright weightbearing position to acquire the position of the patella with respect to the femur. Patellar tilt and bisect offset were measured, and patellofemoral pain participants were classified into normal tracking and maltracking groups. RESULTS: Correlations between VM activation delay and patellar maltracking measures were statistically significant in only the patellofemoral pain participants classified as maltrackers with both abnormal tilt and abnormal bisect offset (R(2) = .89, P < .001, with patellar tilt during walking; R(2) = .75, P = .012, with bisect offset during jogging). There were no differences between the means of activation delays in pain-free and all patellofemoral pain participants during walking (P = .516) or jogging (P = .731). CONCLUSION: There was a relationship between VM activation delay and patellar maltracking in the subgroup of patellofemoral pain participants classified as maltrackers with both abnormal tilt and abnormal bisect offset. CLINICAL RELEVANCE: A clinical intervention such as VM retraining may be effective in only a subset of patellofemoral pain participants-namely, those with excessive tilt and excessive bisect offset measures. The results highlight the importance of appropriate classification of patellofemoral pain patients before selection of a clinical intervention.
BACKGROUND: Delayed onset of vastus medialis (VM) activity compared with vastus lateralis activity is a reported cause for patellofemoral pain. The delayed onset of VM activity in patellofemoral painpatients likely causes an imbalance in muscle forces and lateral maltracking of the patella; however, evidence relating VM activation delay to patellar maltracking is sparse. The aim of this study was to investigate the relationship between VM activation delay and patellar maltracking measures in pain-free controls and patellofemoral painpatients. HYPOTHESIS: Patellar tilt and bisect offset, measures of patellar tracking, correlate with VM activation delay in patellofemoral painpatients classified as maltrackers. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: Vasti muscle activations were recorded in pain-free (n = 15) and patellofemoral pain (n = 40) participants during walking and jogging. All participants were scanned in an open-configuration magnetic resonance scanner in an upright weightbearing position to acquire the position of the patella with respect to the femur. Patellar tilt and bisect offset were measured, and patellofemoral painparticipants were classified into normal tracking and maltracking groups. RESULTS: Correlations between VM activation delay and patellar maltracking measures were statistically significant in only the patellofemoral painparticipants classified as maltrackers with both abnormal tilt and abnormal bisect offset (R(2) = .89, P < .001, with patellar tilt during walking; R(2) = .75, P = .012, with bisect offset during jogging). There were no differences between the means of activation delays in pain-free and all patellofemoral painparticipants during walking (P = .516) or jogging (P = .731). CONCLUSION: There was a relationship between VM activation delay and patellar maltracking in the subgroup of patellofemoral painparticipants classified as maltrackers with both abnormal tilt and abnormal bisect offset. CLINICAL RELEVANCE: A clinical intervention such as VM retraining may be effective in only a subset of patellofemoral painparticipants-namely, those with excessive tilt and excessive bisect offset measures. The results highlight the importance of appropriate classification of patellofemoral painpatients before selection of a clinical intervention.
Authors: D B Mach; S D Rogers; M C Sabino; N M Luger; M J Schwei; J D Pomonis; C P Keyser; D R Clohisy; D J Adams; P O'Leary; P W Mantyh Journal: Neuroscience Date: 2002 Impact factor: 3.590
Authors: Frances T Sheehan; Aditya Derasari; Kenneth M Fine; Timothy J Brindle; Katharine E Alter Journal: Clin Orthop Relat Res Date: 2009-05-09 Impact factor: 4.176
Authors: Rachel Chester; Toby O Smith; David Sweeting; John Dixon; Sarah Wood; Fujian Song Journal: BMC Musculoskelet Disord Date: 2008-05-01 Impact factor: 2.362
Authors: Christoph Becher; Benjamin Fleischer; Marten Rase; Thees Schumacher; Max Ettinger; Sven Ostermeier; Tomas Smith Journal: Knee Surg Sports Traumatol Arthrosc Date: 2015-10-19 Impact factor: 4.342
Authors: Lowell M Smoger; Clare K Fitzpatrick; Chadd W Clary; Adam J Cyr; Lorin P Maletsky; Paul J Rullkoetter; Peter J Laz Journal: J Orthop Res Date: 2015-06-23 Impact factor: 3.494
Authors: Saikat Pal; Thor F Besier; Gary S Beaupre; Michael Fredericson; Scott L Delp; Garry E Gold Journal: J Orthop Res Date: 2012-11-19 Impact factor: 3.494
Authors: Rachel L Lenhart; Colin R Smith; Michael F Vignos; Jarred Kaiser; Bryan C Heiderscheit; Darryl G Thelen Journal: J Biomech Date: 2015-05-22 Impact factor: 2.712
Authors: Saikat Pal; Thor F Besier; Christine E Draper; Michael Fredericson; Garry E Gold; Gary S Beaupre; Scott L Delp Journal: J Orthop Res Date: 2011-11-15 Impact factor: 3.494
Authors: Kristen A Herbst; Kim D Barber Foss; Lauren Fader; Timothy E Hewett; Erik Witvrouw; Denver Stanfield; Gregory D Myer Journal: Am J Sports Med Date: 2015-09-01 Impact factor: 6.202
Authors: Rachel L Lenhart; Darryl G Thelen; Christa M Wille; Elizabeth S Chumanov; Bryan C Heiderscheit Journal: Med Sci Sports Exerc Date: 2014-03 Impact factor: 5.411