Patellofemoral Joint Forces During Ergometric Cycling

Transcription

1 Patellofemoral Joint Force During Ergometric Cycling MATS O. ERICSON and RALPH NISELL We etimated the patellofemoral joint force generated during pedaling on a bicycle ergometer. Our calculation were baed on meaurement from a force tranducer mounted on the pedal, 16-mm cine-film equence, and biomechanical model of the cycling motion and of the patellofemoral joint. Six healthy male ubject cycled at different work load, pedaling rate, addle height, and pedal foot poition. The maximum patellofemoral compreive force wa N (1.3 time body weight [BW]) when cycling with an foot poition at W, rpm, and dle addle height. The mean peak compreive force between the quadricep tendon and the intercondylar groove wa N (0.4 BW), and the patellar-tendon and quadricep-tendon train force were N (0.9 BW) and N (1.3 BW), repectively. The patellofemoral joint force were increaed with increaed work load or decreaed addle height. Different pedaling rate or foot poition did not ignificantly change thee force. Key Word: Biomechanic, Exercie therapy, Knee, Patella. Pedaling on a bicycle ergometer i one poible treatment of patient with patellofemoral diorder 1-5 or rheumatoid arthriti. 6 Knowledge of the magnitude of the patellofemoral joint force generated during bicycling may be valuable to phyical therapit who treat patient with load-elicited pain from the patellofemoral joint. Patient, by appropriately adjuting the bicycle ergometer and their own cycling technique, may achieve a decreae in patellofemoral joint force that till would give them adequate quadricep-tendon exercie while reducing pain. The moment of force acting about the knee joint during exercie on a bicycle ergometer have been reported recently. 7,8 In thee tudie, a force-meauring pedal wa ued. If the reaction force applied to the foot from the pedal are known, the moment of force acting about the bilateral hip, knee, and ankle joint axe can be calculated uing dynamic mechanic. 9 During tandardized ergometric cycling, defined a W, rpm, dle addle height, and foot poition, the mean peak knee flexion and extenion load moment (counteracted by a mucular moment) acting about the bilateral knee joint axi are about 29 N. m and 12 N. m, repectively. 8 The knee load moment acting about the anteropoterior knee joint axi are about 25 N. m in a varu direction and 3 N. m in a valgu direction. 7 The tibiofemoral peak compreive force and the ly directed peak hear force mainly treing the cruciate ligament recently were etimated to be about 1.2 and 0.05 time body weight (BW), repectively. 10 Niell and Ekholm contructed a biomechanical model for etimating the magnitude of patellofemoral compreive force, patellar-tendon and quadricep-tendon train force, Dr. Ericon i a member of the Kineiology Reearch Group, Department of Anatomy and Department of Phyical Medicine and Rehabilitation, Karolinka Intitute, PO Box 400, S Stockholm, Sweden. Dr. Niell i a member of the Kineiology Reearch Group, Department of Anatomy, Karolinka Intitute. Thi article wa ubmitted March 10, 1986; wa with the author for reviion 27 week; and wa accepted January 21, Potential Conflict of Interet: 3. and compreive force between the quadricep tendon and the femoral intercondylar groove. 11 Their tudy howed that with a contant knee flexion load moment (counteracted by knee extenion), the patellofemoral compreive force increae with an increaed kneeflexionangle. At knee flexion angle greater than 90 degree, however, the patellofemoral compreive force diminihe lightly. The magnitude of the kneeflexionload moment and the degree of knee joint flexion preent are the deciive factor for the patellofemoral joint force magnitude during variou activitie. In ergometric cycling, the maximum kneeflexionload moment i ignificantly increaed by a work-load increae or by a addle height decreae. 8 Different pedaling rate or foot poition do not ignificantly affect the magnitude of the maximum knee flexion load moment. 8 In thi tudy, we ued the data preented on knee load moment during ergometric cycling 8 and a biomechanical model for patellofemoral joint force 11 to calculate the patellofemoral joint force induced. The purpoe of our tudy wa to quantify the magnitude of patellofemoral compreive force obtained during ergometric cycling. We etimated the compreive force between the quadricep tendon and the intercondylar groove and the train force in the patellar and quadricep tendon achieved during cycling. Change in thee force caued by change in ergometric work load, pedaling rate, addle height, or pedal foot poition alo were tudied. METHOD Subject The ubject were ix healthy men aged 20 to 31 year, ( = 25.3 year), who gave their informed conent to participate in the tudy. Their average height and weight were 1.8 m ( =.06) and 71.3 kg ( = 5.0). The ubject were tudent with ordinary daily and recreational cycling experience. None of the ubject uffered from locomotor pain, previouly had undergone joint urgery, or had a hitory of muculokeletal diorder. Volume 67 / Number 9, September

2 Procedure We ued a bicycle ergometer* with weight brake and a pecially intrumented pedal to tudy the following variable: 1. Work load: 0,, and 240 W. 2. Pedaling rate: 40,,, and 100 rpm. 3. Saddle height: low,, and high, determined a a percentage (102%, 113%, and %, repectively) of the ditance between the ichial tuberoity and the medial malleolu a meaured on each ubject. The addle height wa meaured a the greatet ditance from addle urface to the center of the upper pedal urface in a traight line along the addle pillar and crank. 4. Foot poition: one and one poterior foot poition. The foot poition occurred when the center of the pedal wa in contact with the head of the econd metataru (ball of the foot), and the poterior foot poition occurred about 10 cm backward (intep). Table 1 how the different tet combination tudied. We choe to exclude combination 8 and 10 from the biomechanical analyi. Cycling in the highet addle poition and uing the poterior foot poition (combination 10) gave an unnatural cycling poition with tendencie to have pelvic rocking and hip motion in the frontal plane. To eliminate ytemic effect of fatigue, we randomized the internal equence of the 11 different tet ituation. When one of the four variable wa changed and tudied, the other three were held contant. The only exception wa that when the pedaling rate wa changed (40,,, and 100 rpm), a braking weight of 2 kg wa ued and hence the work load were,, 1, and 200 W, repectively. The different work load were regulated by adding weight (0, 2, and 4 kg) to the weight-braked bicycle ergometer. We choe W, rpm, dle addle height, and foot poition a the contant variable, which i the combination referred to a tandardized ergometric cycling. The variou addle height were adjuted to the nearet fixed poition with a maximum error of ± 1.5 cm. The handlebar were kept level with the addle. The cyclit' trunk wa inclined forward 20 to 30 degree from the vertical poition. All ubject were allowed to warm up and familiarize themelve with cycling on the pecially intrumented bicycle ergometer. They practiced at all of the different work load, pedaling rate, addle height, and foot poition included in the tudy. All meaurement were taken on the left lower limb. A piezoelectric quartz force tranducer wa mounted in the left pedal. The equipment allowed u to meaure force in the three orthogonal dimenion (x, y, and z). We ued the x and z force in the agittal plane to calculate the moment of force about the bilateral knee joint axi. The force were recorded on a UV recorder. We mounted a witch on the bicycle ergometer for marking on the UV recorder the top poition of the crank for each revolution. Uing a pecially deigned time indication panel with a light-emitting diode diplay giving a bar repreentation of time in unit down to 1 mec, we could record time on the UV recorder parallel to the force * Cardionic AB, Fröätrabacken 24, S , Skärholmen, Sweden. Model 9251-A, Kitler Intrument Corp, 75 John Glenn Dr, Amhert, NY 14. Model 1508 Viicorder, Honeywell Inc, Medical Electronic Div, 1 Campu Dr, Pleaantville, NY 105. TABLE 1 Summary of Combination of Ergometric Cycling Tet Tet 1 a to 11 Work Load (W) Pedaling Rate (rpm) Saddle Height low low high high Foot Poition poterior poterior poterior a Combination 2 i defined a tandardized ergometric cycling. and crank top poition. The different tet ituation were filmed uing a 16-mm cine-film camera that hot frame a econd, mounted perpendicular to the agittal plane of the ubject at a ditance of 3.5 m. To identify landmark for the bilateral hip, knee, and ankle joint axe, we placed dye mark on the kin at about 1 cm and uperior to the tip of the great tubercle of the femur, at the center of the lateral femoral epicondyle, and at the tip of the lateral malleolu. Time, a indicated by the time indication panel, wa viible on each film frame. The ubject cycled for about 30 econd during each tet before we took the meaurement. A metronome enabled each ubject to find and maintain the correct pedaling rate. We filmed the ubject and recorded the force during fiveecond interval. One of the approximately five revolution recorded on the UV recorder wa elected and analyzed throughout the complete pedal revolution. We analyzed the film with an Analector ANL4 projector," which allowed u to freeze the film and trace the picture at approximately 15- degree interval of the crank angle. The poition of the hip, knee, and ankle joint axe were determined uing the traced picture. The pedal and joint angle were meaured from the cine-film. The x and z force value correponding to each picture were read from the UV recorder. The model ued in thi tudy for calculating knee load moment wa baed on dynamic mechanic, which took into account the dynamically induced force and moment caued by force of inertia and tranlational motion of the lower limb. 9 The knee load moment had been calculated previouly from known crank angle, pedal plane angle, joint poition, and pedal reaction force. 8 Patellofemoral Joint Force Analyi Biomechanical model of the patellofemoral joint, baed on anatomical data and mechanical principle, have been preented and explained in detail elewhere. 11 Uing thi patellofemoral joint model (Fig. 1), the patellofemoral joint force can be quantified if the knee flexion load moment (Mk) and knee flexion angle are known. The patellar moment arm Bolex, Div of Paillard, Inc, 1900 Lower Rd, Linden, NJ 036. Oud Delft, Div of Foreign Adviory Service Corp, Rte 1, Prince Anne, MD PHYSICAL THERAPY

3 RESEARCH Fig. 1. Free-body diagram of patella and dital part of the quadricep tendon. Patellofemoral compreive force (Fcp) equal vector um of patellar-tendon train force (Fp) and quadricep-tendon train force (Fq). The Fcp, which i perpendicular to the joint urface, project through the Fp-Fq interection point (X) and the center of patellofemoral joint contact point (M). The patellar moment arm (dp) and compreive force between quadricep tendon and femoral intercondylar groove (Fcq) are hown alo. (Adapted from Niell. 12 ) i denoted dp. The magnitude of the patellofemoral compreive force (Fcp), the patellar-tendon train force (Fp), the quadricep-tendon train force (Fq), and the compreive force between the quadricep tendon and the femoral intercondylar groove (Fcq) may be determined by the following equation: Data Analyi Fp = Mk/dp (1) Fcp = Fp (in Ψ)/(in e) (2) Fq = Fcp (co e) + Fp (co Ψ) (3) The ignificance of change in patellofemoral joint force caued by change in work load, pedaling rate, addle height, and foot poition wa determined tatitically uing a onefactor analyi of variance (ANOVA) for repeated meaure. The level of ignificance wa et at.05. RESULTS Fcq = 2 Fq (in λ/2) (4) The knee load moment, knee angle, Fcp, Fp, Fq, and Fcq calculated during tandardized ergometric cycling are hown in Figure 2. Zero- and 3-degree crank angle correpond to the pedal top poition, and the 1-degree crank angle correpond to the pedal bottom poition. The Fcp, Fp, and Fq peaked at the -degree crank angle (ie, during the downtroke before the crank became horizontal). The Fcq occurred between the 315- and -degree crank angle and peaked at the 30-degree crank angle. Figure 3 how patellofemoral joint force in relation to knee angle. The mean peak Fcp during tandardized ergometric cycling meaured N ( = 240) and occurred at a mean knee angle of 83 degree ( = 6). At the ame knee angle, the peak Fp and Fq alo were preent, meauring N ( = ) and N ( = ), repectively. The mean peak Fcq meaured N ( = ) at a mean knee angle of 108 degree ( = 7). Fig. 2. Knee load moment, knee joint angle, patellar-tendon train force (Fp), quadricep-tendon train force (Fq), patellofemoral compreive force (Fcp), and compreive force between quadricep tendon and femoral intercondylar groove (Fcq) induced during complete crank revolution. Fig. 3. Patellar-tendon train force (Fp), quadricep-tendon train force (Fq), patellofemoral compreive force (Fcp), and compreive force between quadricep tendon and femoral intercondylar groove (Fcq) plotted againt knee joint angle. Figure 4 how the change in patellofemoral joint force magnitude caued by change of the different adjutment factor. The magnitude of the compreive and train force increaed ignificantly with an increaed work load or decreaed addle height. Thee force were not changed ignificantly by a change in pedaling rate or pedal foot poition (Tab. 2). DISCUSSION In our tudy, the peak Fcp induced during tandardized ergometric cycling wa calculated to be N (1.3 BW), which may be imilar to compreive force obtained during other activitie. Niell etimated the patellofemoral joint force during variou activitie uing knee moment and knee joint angle data reported by other. 12 The maximum Fcp induced during tandardized ergometric cycling i imilar to that induced during normal level walking. 13,14 The Fcp produced during cycling i about 50% of that produced when acending tair 15 and 20% of that generated when decending tair. 15 During maximum iokinetic knee extenion at 30 / Volume 67 / Number 9, September

4 Fig. 4. Change in patellar-tendon train force (Fp), quadricep-tendon train force (Fq), patellofemoral compreive force (Fcp), and compreive force between quadricep tendon and femoral intercondylar groove (Fcq) caued by change of ergometer work load, pedaling rate, addle height, or pedal foot poition. ec, the Fcp i about 10 time that induced during cycling. 16 One mut conider that the magnitude of the Fcp induced during cycling depend almot entirely on the ergometric work load or addle height ued, not on the ubject' body weight. The Fcp expreed a BW, therefore, will be relatively maller for heavier ubject. Our reult how that the compreive force (Fcp and Fcq) obtained during cycling could be decreaed even more by a reduction in work load or an increae in addle height. The magnitude of Fcp induced during cycling i governed by the magnitude of knee load moment and the knee joint angle. When the addle height wa decreaed, the knee load moment increaed ignificantly, and the knee joint angle increaed. 8 Conequently, the patellofemoral joint force induced at lower addle height increaed. The clinical experience i that ome people complain about knee joint pain induced during cycling. 17 The caue of thi pain i unclear. The compreive force are imilar to, or omewhat higher than, thoe produced during normal level walking, but lower than thoe produced during mot other activitie. The main difference between cycling and walking i that the knee i much more flexed during cycling. Fairbank et al propoed that knee joint pain i caued by overue, uch a repetitive loading. 18 Niell and Ekholm earlier tated that patient with load-elicited pain from the patellofemoral joint might be advied to avoid knee angle above 30 degree under loaded condition. 11 A recently dicued by Niell, however, the magnitude of the patellofemoral contact area varie with knee joint angle. 12 The larget contact area i reported at to 90 degree of kneeflexion,and the mallet contact area occur when the knee i traight. 19,20 Conequently, the patellofemoral preure, even when the knee i almot traight, may be coniderable, although the compreive force eem to be comparatively low. In cycling, the knee iflexedmore than 30 degree during mot of the revolution of the crank. Dickon tated that many bicycleridermake two major error; they either et the addle too low or et the gear too high. 17 To avoid development of knee pain, therefore, addle height mut be adjuted properly and the work load hould not be too high. The Fcq occurred at large knee flexion angle with a peak of N at the 108-degree knee angle. Thi Fcq ha been dicued in the literature and might lead to compreion of the upper part of the uprapatellar bura, in ome cae even cauing pain We only can peculate about the etiological factor influencing knee pain induced for ome people during cycling, but factor uch a increaed knee flexion and compreion of the uprapatellar bura and the patellofemoral joint certainly are of coniderable importance. Lindberg relied heavily on the ue of the bicycle ergometer in the treatment of patient with patellofemoral pain yndrome. 3 He tated that a bicycle ergometer enable phyical training with load ranging from light to heavy. Uing minimum reitance, a ituation i created that replicate paive movement of the knee joint. A oon a poible, Lindberg' patient were put on the bicycle ergometer, uing minimum or no load, and the reitance wa increaed gradually. The bicycle exercie wa ued both for improving joint mobility and mucle trengthening. 3 Baed on the reult of our tudy and the clinical ue of cycling reported elewhere, we believe that cycling may be a valuable exercie in the treatment of patient with patellofemoral pain yndrome. Proper attention, however, mut be given to the appropriate adjutment of work load and addle height PHYSICAL THERAPY

5 RESEARCH TABLE 2 Mean Patellofemoral Compreive and Strain Force During Ergometric Cycling at Different Adjutment (in Newton) Adjutment Fcp a Fcq b Fp c Fq d Work load (W) Pedaling rate (rpm) Saddle height Low Mid High Foot poition Anterior Poterior 242 1, , , , , ,000 1, , a Fcp = patellofemoral compreive force. b Fcq = compreive force between quadricep tendon and femoral intercondylar groove. c Fp = patellar-tendon train force. d Fq = quadricep-tendon train force. CONCLUSIONS The compreive force (Fcp and Fcq) induced during ergometric cycling generally are lower than that for mot other daily activitie and exercie. The magnitude of patellofemoral joint force (Fp, Fq, Fcp, and Fcq) during cycling are almot independent of the ubject' body weight becaue of itting on the addle. Cycling, therefore, might be preferable for patient who are obee. Finally, the patellofemoral joint force change ignificantly a a reult of change in ergometric work load or addle height, but not with pedaling rate or foot poition. Acknowledgment. Thi tudy wa upported by grant from the Swedih Medical Reearch Council (5720) and the Karolinka Intitute, Stockholm, Sweden. REFERENCES 1. Campbell DE, Glenn W: Rehabilitation of knee flexor and knee extenor mucle trength in patient with menicectomie, ligamentou repair, and chondromalacia. Phy Ther 62:10-15, Hungerford DS, Lennox DW: Rehabilitation of the knee in diorder of the patellofemoral joint: Relevant biomechanic. Orthop Clin North Am 14: , Lindberg U; The Patellofemoral Pain Syndrome. Doctoral Diertation. Linkoping Medical Diertation No Linkoping, Sweden, Pevner DN, Johnon JRG, Blazina ME: The patellofemoral joint and it implication in the rehabilitation of the knee. Phy Ther 59: , Steadman JR: Nonoperative meaure for patellofemoral problem. Am J Sport Med 7: , Nordemar R, Berg U, Ekblom B, et al: Change in mucle fibre ize and phyical performance in patient with rheumatoid arthriti after 7 month phyical training. Scand J Rheumatol 5: , Ericon MO, Niell R, Ekholm J: Varu and valgu load on the knee joint during ergometer cycling. Scandinavian Journal of Sport Science 6:39-45, Ericon MO, Bratt Å, Niell R, et al: Load moment about the hip and knee joint during ergometer cycling. Scand J Rehabil Med 18: , Bratt Å, Ericon MO: Biomechanical model for calculation of joint load during ergometer cycling. TRITA-MEK 85-05:1-36, Ericon MO, Niell R: Tibiofemoral joint force during ergometer cycling. Am J Sport Med 14: , Niell R, Ekholm J: Patellar force during knee extenion. Scand J Rehabil Med 17:63-74, Niell R: Mechanic of the knee: A tudy of joint and mucle load with clinical application. Acta Orthop Scand [Suppl 216] 56:1-42, Winter DA: Overall principle of lower limb upport during tance phae of gait. J Biomech 13: , Boccardi S, Pedotti A, Rodano R, et al: Evaluation of mucular moment at the lower limb joint by an on-line proceing of kinematic data and ground reaction. J Biomech 14:35-45, Andriacchi TP, Anderon GB, Ferlier RW, et al: A tudy of lower-limb mechanic during tair-climbing. J Bone Joint Surg [Am] 62: , Niell R, Ericon MO, Nemeth G, et al: Tibio-femoral joint force during iokinetic knee extenion. Am J Sport Med, to be publihed 17. Dickon TB: Preventing overue cycling injurie. The Phyician and Sportmedicine 13(10): , Fairbank JC, Pynent PB, van Poortvliet JA, et al: Mechanical factor in the incidence of knee pain in adolecent and young adult. J Bone Joint Surg [Br] 66: , Matthew LS, Sontergaard DA, Henke JA: Load-bearing characteritic of the patello-femoral joint. Acta Orthop Scand 48: , Huberti HH, Haye WC: Patellofemoral contact preure. J Bone Joint Surg [Am] 66: , Goodfellow JW, Hungerford DS, Zindel M: Patello-femoral joint mechanic and pathology: 1. Functional anatomy of the patello-femoral joint. J Bone Joint Surg [Br] 58: , Bihop RE: On the mechanic of the human knee. Eng Med 6:46-52, Grood ES, Suntay WJ, Noye FR, et al: Biomechanic of the knee extenion exercie. J Bone Joint Surg [Am] 66: , 1984 Volume 67 / Number 9, September