Walking ability of individuals fitted with transfemoral bone-anchored prostheses: A comparative study of gait parameters

Associations Between Skeletal Alignment and Biomechanical Symmetry Before and After Transfemoral Bone-anchored Limb Implantation

BACKGROUND

Patients with transfemoral amputation experience socket-related problems and musculoskeletal overuse injuries, both of which are exacerbated by asymmetric joint loading and alignment. Bone-anchored limbs are a promising alternative to treat chronic socket-related problems by directly attaching the prosthesis to the residual limb through an osseointegrated implant; however, it remains unknown how changes in alignment facilitated through a bone-anchored limb relate to loading asymmetry.

QUESTIONS/PURPOSES

What is the association between femur-pelvis alignment and hip loading asymmetry during walking before and 12 months after transfemoral bone-anchored limb implantation?

METHODS

Between 2019 and 2022, we performed 66 bone-anchored limb implantation surgeries on 63 individuals with chronic socket-related problems. Of those, we considered those with unilateral transfemoral amputation as potentially eligible for this study. Based on that, 67% (42 of 63) were eligible, a further 55% (23 of 42) were excluded because they had incomplete datasets either at baseline (such as an inability to ambulate with a socket prosthesis) or did not complete the 12-month follow-up data collection. This resulted in 19 participants being included in this retrospective longitudinal analysis (9 males and 10 females, mean ± age 51 ± 11 years, mean BMI 28 ± 4 kg/m2). As part of standard clinical care, hip-to-ankle radiographs and motion capture data during overground walking were collected at two timepoints: 2 days before (preimplantation) and 12 months after bone-anchored limb implantation (postimplantation). Femur-pelvis skeletal alignment was measured from the radiographs (femoral abduction angle, residual femur length ratio, and pelvic obliquity). Symmetry indices of hip internal hip moment impulses (flexion/extension, abduction/adduction, internal/external rotation) were calculated from the motion capture data. Differences in alignment and internal joint moment impulse symmetry indices were compared across timepoints using paired t-tests with self-selecting walking speed as a covariate. Associations between skeletal alignment and hip moment impulse symmetry indices were computed at both timepoints using Spearman rank correlation with 5000 bootstrapped resamples.

RESULTS

Twelve months after bone-anchored limb implantation, a comparison of preimplantation and postimplantation measurements showed reductions in the femoral abduction angle (-8° ± 10° versus 3° ± 4°, mean difference 11° [95% confidence interval (CI) 7° to 16°]; p < 0.001) and the residual femur length ratio (57% ± 15% versus 48% ± 11%, mean difference -9% [95% CI -12% to -5%]; p < 0.001). Additionally, a comparison of preimplantation and postimplantation calculations showed that the internal hip moment symmetry was improved in the sagittal and frontal planes (flexion symmetry index: 30 ± 23 versus 11 ± 19, mean symmetry index difference -19 [95% CI -31 to -6]; p = 0.03; extension symmetry index: 114 ± 70 versus 95 ± 63, mean symmetry index difference -19 [95% CI -42 to 4]; p = 0.03; abduction symmetry index: -54 ± 55 versus -41 ± 45, mean symmetry index difference 13 [95% CI -15 to 40]; p = 0.03). A larger length ratio of the residual limb relative to the intact limb was moderately associated with hip moment impulse symmetry in all three anatomical planes of motions both before and 12 months after transfemoral bone-anchored limb implantation, with strong associations observed between postimplantation hip extension and external rotation moment impulse symmetry (extension: ρ = -0.50 [95% CI -0.72 to -0.07]; p = 0.03; internal rotation: ρ = 0.64 [95% CI 0.25 to 0.85]; p = 0.004).

CONCLUSION

The associations between residual femur length and hip loading symmetry in patients with transfemoral bone-anchored limbs suggest that those with shorter residual limbs will demonstrate more asymmetric joint loading when using a bone-anchored limb. Thus, these findings could potentially be used to better inform targeted interventions based on residual limb morphology, including continued gait training in rehabilitation to promote joint loading symmetry and surgical considerations surrounding limb length changes in those with shorter limbs. Future studies might also examine joint loading symmetry during other activities of daily living after bone-anchored limb implantation to further expand knowledge of how residual limb anthropometry is associated musculoskeletal health after bone-anchored limb implantation.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Cognitive load in individuals with a transfemoral amputation during single- and dual-task walking: a pilot study of brain activity in people using a socket prosthesis or a bone-anchored prosthesis

OBJECTIVE

To explore cognitive load in people with transfemoral amputations fitted with socket or bone-anchored prostheses by describing activity in the left and right dorsolateral prefrontal cortices during single- and dual-task walking.

DESIGN

Cross-sectional pilot study.

PATIENTS

8 socket prosthesis users and 8 bone-anchored prosthesis users. All were fitted with microprocessor-controlled prosthetic knees.

METHODS

Participants answered self-report questionnaires and performed gait tests during 1 single-task walking condition and 2 dual-task walking conditions. While walking, activity in the dorsolateral prefrontal cortex was measured using functional near-infrared spectroscopy. Cognitive load was investigated for each participant by exploring the relative concentration of oxygenated haemoglobin in the left and right dorsolateral prefrontal cortex. Symmetry of brain activity was investigated by calculating a laterality index.

RESULTS

Self-report measures and basic gait variables did not show differences between the groups. No obvious between-group differences were observed in the relative concentration of oxygenated haemoglobin for any walking condition. There was a tendency towards more right-side brain activity for participants using a socket prosthesis during dual-task conditions.

CONCLUSIONS

This pilot study did not identify substantial differences in cognitive load or lateralization between socket prosthesis users and bone-anchored prosthesis users.

Lumbopelvic movement coordination during walking improves with transfemoral bone anchored limbs: Implications for low back pain

BACKGROUND

Low back pain (LBP) is more prevalent in patients with transfemoral amputation using socket prostheses than able-bodied individuals, in part due to altered spinal loading caused by aberrant lumbopelvic movement patterns. Early evidence surrounding bone-anchored limb functional outcomes is promising, yet it remains unknown if this novel prosthesis influences LBP or movement patterns known to increase its risk.

RESEARCH QUESTION

How are self-reported measures of LBP and lumbopelvic movement coordination patterns altered when using a unilateral transfemoral bone-anchored limb compared to a socket prosthesis?

METHODS

Fourteen patients with unilateral transfemoral amputation scheduled to undergo intramedullary hardware implantation for bone-anchored limbs due to failed socket use were enrolled in this longitudinal observational cohort study (7 F/7 M, Age: 50.2±12.0 years). The modified Oswestry Disability Index (mODI) (self-reported questionnaire) and whole-body motion capture during overground walking were collected before (with socket prosthesis) and 12-months following bone-anchored limb implantation. Lumbopelvic total range of motion (ROM) and continuous relative phase (CRP) segment angles were calculated during 10 bilateral gait cycles. mODI, total ROM, CRP and CRP variabilities were compared between time points.

RESULTS

mODI scores were significantly reduced 12-months after intramedullary hardware implantation for the bone-anchored limb (P = 0.013). Sagittal plane trunk and pelvis total ROM during gait were reduced after implantation (P = 0.001 and P < 0.001, respectively). CRP values were increased (more anti-phase) in the sagittal plane during single limb stance and reduced (more in-phase) in the transverse plane during pre-swing of the amputated limb gait cycle (P << 0.001 and P = 0.029, respectively). No differences in CRP values were found in the frontal plane.

SIGNIFICANCE

Decreases in mODI scores and lumbopelvic ROM, paired with the changes in lumbopelvic coordination, indicate that bone-anchored limbs may reduce LBP symptoms and reduce compensatory movement patterns for people with unilateral transfemoral amputation.