Bilateral Hip Replacement | Gait Cycle
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Added on 2019-12-28
Bilateral Hip Replacement | Gait Cycle
Added on 2019-12-28
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Bergmann et al., (1993) also treated a patient who was suffering from a bilateral hipreplacement. During gait cycle it was compared that the force magnitude and direction werecontrary for two hips. The differences between two hips may be because of differences caused bysurgery in muscle strength, or different placement position of implant or may be due tophysiological differences between right and left sides of patient. It clearly indicates thatinvestigations into the mechanisms behind this phenomenon are vital. Some differences between theright and left faces of normal subjects, which can be assumed to have both hips in normal centre ofrotation, have been foreseen applying gait analysis and musculoskeletal models and therefore someof inequality has found in bilateral hip replacement of the patient could be due to natural variation. Some studies have also measured the forces gained during other activities.(Rydell 1966;Davy et al. 1988; Bergmann et al. 1993; Bergmann et al. 2001) Walking at normal and fast speeds,2-1-2 stance, stair descending and stair climbing are the activities that generate largest forces. Whenpatients were stumbled, the most intense forces were recorded. Two patients (Patient EB left hip andPatient JB, Bergmann et al. 1993) were recorded while stumbling and generating 7.2 BW and 8.7BW across their hips, but they were unable and were not interested to subsequently produce theseforces voluntarily. Commonly the literature depicts that during gait, the peak force at heel strike ishigher than at toe off (Davy et al. 1988; Lu et al. 1998; Bergmann et al. 2001). However, it has been shown by Brand et al. (1994) that the toe off to heel strikes ratio is notalways continual within the same patient. There are studies that support the fact that some patientspossess a greater peak at toe off as compared with heel strike (Davy et al. 1988; Bergmann et al.2001). Davy et al. (1988) examined three partial load bearing patients who were using crutches . Heidentified that only one of the patient out of three has a toe off force more than heel strike. Thepatient KWR in Bergmann et al‟s study had eight normal speed. Catherine Manders revise of thehip joint gait cycles published of which two of them showed a higher or same magnitude toe offthan to the heel strike force. Definitive conclusion cannot be drawn because of limited number ofstudies and various conditions under which studies were conducted. However, the range ofoutcomes illustrated in literature do shows range of variability within one patient and inter-patientvariability.Measured forces recorded through instrumented hip replacements have found an averageextreme point hip contact force at normal walking speed without aids to be 2.69 BW using thestudies by Rydell et al, (1966) Brand et al. (1994), Taylor et al. (1997; 2001) and Bergmann et al.(1993; 2001) (Table 2). Even so there is a great spread of data with minimum value of peak forceduring a gait cycle found in study by Taylor et al. Of 0.9BW (patient JB) in two varying gait cycles.It is tough from the restricted data to acquire realistic average values or obtain variability likely in1
general population, specially when all these patients have undergone with hip replacements. Thenalso the measured data provides an indication of the forces that can be anticipated across hips. Therelies a difference between studies on forces in posterior- anterior direction throughout the gait cycleas shown by Brand et al. (1994) and Bergmann et al (2001) who obtained very different forces inposterior direction. Brands et al. measured forces of approximately HS and force stayed in ananterior direction throughout gait cycle. Whereas patients in study conducted by Bergmann et al.had measured a peak posterior force between 0.2 BW and 0.6 BW at HS.The reported literature recommends that peak forces across an implanted hip areapproximately 3.5 BW eliminating events like stumbling. The range of data published includesdifferent patients and a varied range of instrumentation design. These extreme forces increasepostoperatively meeting a relatively constant level in force magnitude after 16 days approximately(Davy et al. 1988). However, range of peak Catherine Manders review of hip joint forces in theliterature for normal gait is 2.11-3.5 BW and the majority of outcomes are in a smaller range of 2.5-3 BW. It must be taken into account that such small number of patients do not let stiff conclusionsto be drawn for general population. It is essential to understand and quantify the forces experiencedat hip because this permits any replacement joints to be modelled and examined under reasonableconditions. At present there are not techniques available for measuring the muscle forces directly andtherefore indirect methods of investigating muscle force and activity has been formulated.Musculoskeletal models can anticipate muscle forces and are elaborated in chapter 3.1.Electromyography (EMG) allows recording of electrical signal form muscles. This technique usespairs of electrodes, which are indistinguishable to remove galvanic potential, to record voltagepotential across muscle. This potential is directly linked to electrical impulses causing movement inmuscle. Majorly there are two types of electrode: surface and indwelling. Surface electrodes can betaken in use to investigate only surface muscles. For studying underlying muscles, indwellingelectrodes like wire electrodes can be inserted through skin by using a needle into muscle below.(Vaughan et al. 1992).EMG can be utilised to investigate which muscles are progressive during the gait cycle andthen those findings can be compared with activity levels form musculoskeletal models(Crowninshield and Brand 1981) (Chapter 3.1). Vaughan et al. (1992) measured EMG of 28 majormuscles in lower extremity of a normal human being during gait cycle (Figure 13). Several studieshave been published which justifies use of EMG data as a validation method (Crowninshield andBrand 1981; Glitsch and Baumann 1997; Hoek van Dijke et al. 1999). To determine if acomputational model is modelling a realistic body response to movement, onset and offset points of2
activity form EMG readings can be used. Some studies have graduated the readings form EMG topredict forces producted by muscles (Milner-Brown and Stein 1975; Cholewicki and Mcgill 1994;Lloyd and Besier 2003) but this is tough as presently the methods for calibrating force are notalways reasoned reliable (Erdemir et al. 2007). . 3
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