IntroductionTwo treatment procedures can be implemented when dealing with leg length discrepancies associated with Proximal Femoral Focal Deficiency (PFFD). The knee can be fused along with a Van Nes rotationplasty (VNR) or Syme's amputation (SA). Advocates of the VNR claim that it provides a more efficient gait, while advocates of the SA claim that it provides a limb that is easier to fit with a prosthesis, provides a better body image, and that the VNR does not really encourage a more efficient gait. The purpose of this study was to compare the VNR and SA for the treatment of PFFD in terms of perceived physical appearance, gross motor function, metabolic energy cost of ambulation, and biomechanical gait analysis.MethodologyAll subjects were between the ages of 8 and 20 years with a mean age of 14.4 years. Hip status using the Aitken's classification system and the Hospital for Sick Children (HSC) system, gross motor function using the Rand Health Insurance Study (HIS) instrument, and perceived physical image using the Denver profile for adolescents was determined for 9 VNR and 7 SA subjects. Metabolic energy cost of ambulation was measured for 7 VNR and 5 SA subjects using a Beckman metabolic cart. Joint angle, torque, and power time histories during gait were obtained via a motion tracking system [VICON] and force plate for 2 VNR and 2 SA subjects. T-tests were carried out on all results except the biomechanical gait results since only 2 subjects in each group were involved.ResultsA significant difference was not seem between groups in hip status (HSC: VNR=1.44, SA=1.43; Aitken: VNR=2.33, SA=2.43), physical appearance as seen by the Denver profile (VNR=2.4, SA=2.8), or gross motor function as seen by the Rand HIS scores (VNR=10.56, SA=10.43).Metabolic energy cost of ambulation results showed no significant difference in net oxygen utilization per minute, but the SA group was slightly higher (10.98 ml. O2/kg. min) than the VNR group (9.74 ml. O2/kg. min). The VNR group showed a statistically significantly better net efficiency (0.153 ml. O2/kg m) when compared to the SA group (0.169 ml. O2/kg. m) (p<0.05).Temporal results (Table 1) indicate that the VNR encourages a larger stride length and a shorter stride time, resulting in a faster velocity. The stance/swing ratio for able-bodied gait is 1.5. The VNR group was able to maintain a closer to normal stance/swing ratio than the SA group.Since the aim of the VNR is to essentially lower the level of amputation to that of a below-knee amputee (BKA), comparisons were made between each group and BKA data obtained from a previous study. The VNR group exhibited a slight increase in flexion throughout the gait cycle in comparison to BKA gait (Figure 1). Early transition into hip extension was also seen in early stance, reflecting the early activation of a hip flexor torque and hip power absorption instead of generation. The VNR group apparently thrusted their hip into extension in early stance, probably to keep their centre of mass on top of the prosthesis. The SA group showed increased hip flexion with external rotation throughout gait with excessive adduction throughout stance. Large torque and power profiles were also seen in all three planes. The quick flexion and extension movement and large torque and powers in early swing show how this group used their upper body movement to thrust their affected limb into swing.The VNR group locked their affected knee into neutral during stance, while the BKA group locked their knee with some flexion during stance (Figure 2). This translated into a lack of power absorption in early stance. This action is probably for stability since the affected knee joint in VNR subjects is not as stable as that of BKA. The SA group affected knee profile was similar to that of the VNR group, with a locked knee in neutral in stance. Large power fluctuations in the sagittal plane were also seen during swing. The ankle profiles of the affected side for both groups were similar to that of BKAs.The unaffected hip of the VNR group was similar to that of BKAs, but the SA group exhibited increased hip flexion throughout gait which caused large power fluctuations during foot-contact in all three planes with a prolonged hip generation in swing (Figure 3). It is apparent that the SA group used their hip to propel themselves during gait. The knee profiles of the unaffected side for both groups were similar to that of BKAs.The unaffected ankle of the VNR group was similar to that of BKAs but the SA group dorsiflexed earlier in stance (Figure 4). Two phases of plantarflexion were seen; in early stance, and at toe off. This translated into an early plantarflexor torque and power generation in stance. This group plantarflexes early on their unaffected side, probably to lift their body high enough to allow the prostheses on the affected side to swing through without dragging on the ground.DiscussionIn summary, the results show no differences in perceived body image and gross motor function between subjects with a VNR and a SA. But, the VNR enables a more efficient gait than the SA, and the VNR may also encourage gait patterns which more closely resemble BKA gait patterns than SA does.