Jesse C. Christensen

Diagnosis of Fall Risk in Parkinson Disease: An Analysis of Individual and Collective Clinical Balance Test Interpretation

Background and Purpose: Parkinson disease (PD) results in an increased frequency of falls relative to the frequency in neurologically healthy people. The purpose of this study was to compare the accuracy of PD fall risk diagnosis based on one test with that based on the collective interpretation of multiple tests. Participants: Seventy people with PD (mean age=73.91 years) participated in this study. Method: Clinical balance tests were conducted during the initial examinations of people with PD. Validity indices were calculated for individual tests and compared with validity indices calculated for a combination of multiple tests. Results: Thirty-six participants reported a fall history. Analysis of individual tests revealed broad variations in validity indices, whereas the collective interpretation of multiple tests improved sensitivity and negative likelihood ratios. Discussion and Conclusion: Collective interpretation of clinical balance tests resulted in fewer false-negative results and more substantial adjustments to the posttest probability of being a “faller” than the interpretation of one test alone. These results should be confirmed in a prospective examination of fall risk in PD.

Higher Frequency of Reoperation With a New Bicruciate-retaining Total Knee Arthroplasty

BackgroundWith as many as 25% of patients reporting residual knee symptoms after primary total knee arthroplasty (TKA), alternative implant designs and surgical techniques have been proposed to further reduce these symptoms. There is growing evidence that retention of the anterior cruciate ligament (ACL) results in more natural knee kinematics; thus, implants with more normal joint mechanics could provide improved physical function postoperatively and reduce the amount of residual symptoms. Advancements in the bicruciate-retaining (BCR) TKA implant design have been made, and based on these, we wished to compare the BCR with a more traditional cruciate-retaining (CR) implant.Questions/purposes(1) Was there a difference in the risk of reoperation after primary TKA between BCR and CR implant designs? (2) Was there a difference in the radiographic findings of radiolucent lines (RLLs) between the implant designs? (3) Was there a difference in patient-reported and clinical outcomes between the two implant designs?MethodsBetween January 2013 and May 2014, two surgeons performed 475 primary TKAs. During this time, 78 (16%) of these were performed with BCR implants and 294 (62%) with CR implants; the remainder were performed with anterior-stabilized or more constrained designs as a result of increased deformity and/or ligamentous deficiencies. During this period, the general indications for BCR TKA were arthritic knees with only slight to moderate deformity and sufficient ligamentous integrity of both the ACL and posterior cruciate ligament. The indications for CR TKA were similar other than these patients presented with a deficient ACL. A total of 66 (85%) of the BCR and 237 (81%) of the CR TKAs were available for followup at a minimum of 12 months or when reoperation occurred before 12 months (mean, 18 months; range, 2–32 months). With the numbers available, there were no differences between the groups in terms of age and sex, but the patients undergoing CR TKA had a greater mean body mass index (33 ± 7 versus 31 ± 5 kg/m2, p = 0.032). The frequency of early reoperation was compared between the groups as were radiographic evidence of RLL, patient-reported outcomes, and knee range of motion (ROM).ResultsKnees in the BCR group had a higher frequency of all-cause revision (5% [three of 66] versus 1.3% [three of 237]; hazard ratio (HR), 7.44; 95% confidence interval [CI], 1.24–44.80; p = 0.028). Knees in the BCR group had a higher frequency of irrigation and débridement with component retention (HR, 0.07; 95% CI, 0.02–0.28; p < 0.001). No differences were found between groups for subsequent manipulation (HR, 0.34; 95% CI, 0.08–1.42; p = 0.137). The proportion of RLLs was greater in the BCR group (HR, 2.93; 95% CI, 1.62–5.32; p < 0.001) compared with the CR group. There were no differences between the groups in terms of the Physical Function Computerized Adaptive Test scores, Global10 scores or knee ROM outcomes.ConclusionsPreliminary short-term findings suggest the BCR implant has inferior survivorship and concerning radiographic findings when compared with a conventional CR implant with respect to complications after primary TKA. These findings raise concerns about the new BCR design; however, further randomized trials are necessary to determine superiority between alternative implant designs.Level of EvidenceLevel III, therapeutic study.

Muscle force and movement variability before and after total knee arthroplasty: A review

Variability in muscle force output and movement variability are important aspects of identifying individuals with mobility deficits, central nervous system impairments, and future risk of falling. This has been investigated in elderly healthy and impaired adults, as well as in adults with osteoarthritis (OA), but the question of whether the same correlations also apply to those who have undergone a surgical intervention such as total knee arthroplasty (TKA) is still being investigated. While there is a growing body of literature identifying potential rehabilitation targets for individuals who have undergone TKA, it is important to first understand the underlying post-operative impairments to more efficiently target functional deficits that may lead to improved long-term outcomes. The purpose of this article is to review the potential role of muscle force output and movement variability in TKA recipients. The narrative review relies on existing literature in elderly healthy and impaired individuals, as well as in those with OA before and following TKA. The variables that may predict long-term functional abilities and deficits are discussed in the context of existing literature in healthy older adults and older adults with OA and following TKA, as well as the role future research in this field may play in providing evidence-based data for improved rehabilitation targets.

Kinematics of the Pelvis, Torso, and Lower Limb During Obstacle Negotiation While Under Temporal Constraints

Biomechanics of unobstructed locomotion consists of synchronized complex movements of the pelvis, torso, and lower limbs. These movement patterns become more complex as individuals encounter obstacles or negotiate uneven terrain. To date, limited research has explored how specifically the pelvis, torso, and lower limb segments relate to obstacle negotiation of varying sized objects combined with temporal constraints to perform the task. Understanding pelvis and adjoining segment movements during object negotiation will provide necessary information in identifying abnormal mechanics and potential fall risk characteristics in balance compromised patient populations. In this prospective cohort study, we aimed to compare pelvic, torso, and lower limb kinematics during unobstructed locomotion with obstacle negotiation of varying heights. Ten healthy young adults (7 females and 3 males, mean age 28.4 ± 4.1 years, mean body mass index 22.5 ± 3.6 kg/m2) enrolled in this study. Analysis of within‐subject differences revealed a significant increase in sagittal (posterior tilt) and frontal (ipsilateral hike) plane pelvic angular displacement and higher sagittal plane posterior torso lean angular displacement with increased obstacle height. Furthermore, both sagittal plane hip and knee maximum joint flexion were significantly higher with increasing heights of the obstacles during negotiation. These data provide insight on segment mechanics within a non‐mobility‐impaired population; therefore, providing a baseline to understand the kinematic demands necessary for safe and effective gait in mobility‐compromised populations. Anat Rec, 300:732–738, 2017.

Quadriceps weakness preferentially predicts detrimental gait compensations among common impairments after total knee arthroplasty: QUADRICEPS WEAKNESS INFLUENCES JOINT MECHANICS

Patients with total knee arthroplasty (TKA) have large deficits in physical performance in comparison to their healthy age‐matched peers. Limb asymmetry stemming from less relative load borne by the surgical limb during daily mobility is associated with diminished performance and worsens with greater mobility demands. How common targets of postoperative care, such as muscle weakness, lower limb extension power, residual knee pain, and poor balance confidence can influence asymmetrical limb loading remains unclear. Forty‐six patients with unilateral TKA underwent testing of impairments and motion analysis during 10° decline walking at 3 and 6 months postoperatively. At 3 months, only quadriceps femoris strength asymmetry was found to be significantly related to both total support moment (MT) (β = 0.431; p < 0.001) and knee extensor moment (MK) (β = 0.493; p < 0.001) asymmetry. Again at 6 months, only quadriceps strength asymmetry was related to MT (β = 0.432; p < 0.001) and MK (β = 0.534; p < 0.001) asymmetry. Quadriceps strength significantly improved over time in both limbs, however, deficits between limbs remained. Persistent quadriceps weakness is a key factor associated with walking compensation patterns that are limiting the capacity for greater physical performance of patients with TKA. The pronounced asymmetry in limb and knee loading at 3 months remains unchanged until at least 6 months after surgery, and its association with quadriceps strength asymmetry does not substantially change over time. While other factors may also prompt gait compensations, emphasis on improved quadriceps strength should be a focus of efforts to resolve gait compensations and enhance physical performance outcomes.

Joint mechanical asymmetries during low- and high-demand mobility tasks: Comparison between total knee arthroplasty and healthy-matched peers

Chronic inter-limb joint mechanical asymmetry has been reported following total knee arthroplasty (TKA) during low-demand mobility tasks such as level walking. However, no study has compared the inter-limb asymmetry during a high-demand mobility task such as decline walking. The objective of this cross-sectional study was to compare inter-limb asymmetry differences during both level and decline walking tasks at six months following TKA compared to asymmetry present in an age, gender, body mass index and activity level matched healthy cohort. Kinetic and kinematic gait analysis was conducted on 42 patients with TKA and 15 healthy-matched peers. Our inter-limb asymmetry results demonstrated significantly (p<0.05) greater combined limb support moment (MS) (mean differences [MD]=0.17; 95% CI=0.07, 0.22), knee extensor moment (MK) (MD=0.05; 95% CI=0.02, 0.09) and vertical ground reaction force (vGRF) (MD=0.03; 95% CI=0.01, 0.08) differences during decline walking compared to level walking in patients with TKA. Greater MS (MD=0.24; 95% CI=0.13, 0.35), MK (MD=0.08; 95% CI=0.03, 0.18), vGRF (MD=0.04; 95% CI=0.01, 0.08) and knee joint angle (MD=2.4; 95% CI=0.37, 3.80) differences were present in patients with TKA compared to healthy-matched peers during decline walking. Greater MS (MD=0.13; 95% CI=0.05, 0.20) and plantarflexor moment (MD=0.06; 95% CI=0.04, 0.16) differences were present in patients with TKA compared to healthy-matched peers during level walking. Post-TKA inter-limb asymmetry during level walking worsens as the physical demands of the task are increased. Thus, even patients with good self-reported outcomes after TKA exhibit substantial deficits in their mobility reserves that could limit their independence and community mobility as they age.

Comparison of 2 Forms of Kinetic Biofeedback on the Immediate Correction of Knee Extensor Moment Asymmetry Following Total Knee Arthroplasty During Decline Walking

• BACKGROUND: Individuals with total knee arthroplasty (TKA) display interlimb knee extensor moment (KEM) asymmetry during level walking that is exacerbated as task demands are increased. Studies using biofeedback to correct interlimb KEM asymmetry following TKA have reported mixed results. • OBJECTIVE: To compare the immediate effect of 2 forms of real‐time kinetic biofeedback—vertical ground reaction force (vGRF) or KEM—on improving interlimb peak KEM symmetry during the weight‐acceptance phase of decline walking in persons who have undergone TKA. • METHODS: In this cross‐sectional, controlled laboratory study, 30 participants (17 men; mean ± SD age, 61.9 ± 8.5 years; body mass index, 28.4 ± 3.7 kg/m2) were allocated to either a vGRF or KEM real‐time biofeedback group. Peak KEM interlimb asymmetry was obtained during both nonbiofeedback and biofeedback decline walking trials 3 months following TKA. • RESULTS: Significant interlimb asymmetry in peak KEM was observed in both groups during the nonbiofeedback condition (KEM, P = .02; vGRF, P<.01). The KEM biofeedback group demonstrated an immediate improvement in peak KEM asymmetry (P = .42). No change in peak KEM asymmetry was observed in the vGRF biofeedback group (P = .01). • CONCLUSION: Knee extensor moment biofeedback has an immediate effect on improving peak KEM asymmetry 3 months post TKA. J Orthop Sports Phys Ther 2019;49(2):105‐111. Epub 20 Aug 2018. doi:10.2519/jospt.2019.7800

The Positive Benefits of Negative Movement Patterns Following Total Knee Arthroplasty

Introduction: Eccentric (negative) resistance exercise of the legs using specialized machines has been reported to be useful and often superior to standard exercise following total knee arthroplasty (TKA). Movements that utilize body mass and gravity as a mode of eccentric resistance exercise in a more pragmatic rehabilitation paradigm may also be useful in reversing chronic muscle impairments observed years following surgery. This study explores whether an eccentrically biased, body mass resistance exercise induces greater magnitude of sagittal plane extensor angular impulse of the support torque and individual net joint torque contributions during both squatting and lunging movement patterns 6 weeks following TKA. Methods: Cross-sectional laboratory-based study design including 10 patients following primary unilateral TKA (6.5 ± 0.8 weeks.). All patients completed 3 trials of the squat and lunge movement pattern under both a concentric and an eccentric condition. Extensor angular impulse of the support torque and net joint torque contributions were calculated by integrating the joint torque versus time curves. A Two-way analysis of covariance was conducted and contracts of clinical interest were computed using Wald posttest. P Values for all pairwise comparisons were adjusted for multiplicity using Bonferroni multiple comparison procedure. Results: The eccentric condition, compared to the concentric condition, displayed larger magnitude of extensor angular impulse during both the squat (P < .001) and lunge (P < .001) movement patterns for the support torques. Similarly, the eccentric condition, compared to the concentric condition, displayed larger magnitude of extensor angular impulse of the hip, knee, and ankle (P < .001) during both movement patterns. Conclusion: Eccentrically biased, body mass movement exercises can produce higher levels of extensor angular impulse on the surgical limb in patients early after TKA. Patients in this study were able to tolerate the higher extensor angular impulse demands and performed the eccentrically biased conditions (without specialized machines) that could be beneficial in postoperative rehabilitation.

Influence of Demographics and Utilization of Physical Therapy Interventions on Clinical Outcomes and Revision Rates Following Anterior Cruciate Ligament Reconstruction

STUDY DESIGN: Retrospective cohort from the Intermountain Healthcare system, January 2007 to December 2014. BACKGROUND: Recent evolutions in health care delivery are putting physical therapists in the forefront to be more responsible for providing high‐quality rehabilitation care in a more cost‐effective manner. Studies investigating the association between physical therapy visit utilization and outcomes in vulnerable patient populations following anterior cruciate ligament (ACL) reconstruction may provide useful insights. OBJECTIVES: To examine the relationship between patient age, sex, physical therapy visit utilization, and physical therapy intervention charges with revision rates and patient‐reported outcomes in individuals following primary ACL reconstruction. METHODS: A sample of 660 patients who had an ACL reconstruction was identified through an electronic medical record database. Age and physical therapy visit utilization were categorized to examine effects between groups (20 years of age or younger, 21 to 34 years of age, 35 years of age or older; fewer than 9 visits, 9 to 14 visits, 15 or more visits). Multilevel mixed‐effects linear models were conducted to compare differences between revision rates and patient‐reported outcomes during the episode of care. Receiver operating characteristic curve analyses were also used to determine visit‐number and charge‐per‐visit cut points to discriminate patients who achieved at least a minimal clinically important difference on the patient‐reported outcomes. RESULTS: Of 660 patients, 22 (3.3%) had revision surgery. Compared with patients 20 years and younger, the incidence rate ratio of ACL reconstruction revision was lower in patients who were 35 years and older (85%) and 21 to 34 years (59%). Of 470 patients who attended physical therapy for longer than 3 months, change in Knee Outcome Survey activities of daily living subscale score was significantly lower among patients 20 years of age and younger and in the lowest visit category. CONCLUSION: Achievement of favorable outcomes following ACL reconstruction may require categorization of patients beyond surgical diagnosis alone. Younger patients (aged 20 years or less) attending fewer physical therapy visits (fewer than 9) were more likely to have ACL revision surgery and had inferior patient‐reported outcomes compared to older patients and those with higher physical therapy visit utilization. The study design of a retrospective cohort limits the ability to identify causal relationships. Additionally, this study was conducted in only 1 geographic region within a single health care delivery system, which may limit the generalizability of the results. LEVEL OF EVIDENCE: Prognosis, level 2c.

Stance time variability during stair stepping before and after total knee arthroplasty: A pilot study.

The main objectives of this pilot study were to: (1) investigate stance time variability (STV) during stair stepping in older adults with osteoarthritis (OA) before and after total knee arthroplasty (TKA), and compare to an age- and sex-matched group of healthy controls with native knees and (2) evaluate the relationship between quadriceps strength and STV during stair stepping before and after TKA. A prospective, observational, pilot study was carried out on 13 individuals (15% male, mean age 62.71±6.84years) before and after TKA using an instrumented stairway, patient-reported outcomes, timed stair stepping test, and quadriceps strength measures. At 6-months post-operatively, STV during stair descent was significantly greater in the TKA-GROUP compared to the CONTROL-GROUP, but was not significantly different at 12-months compared to controls. There were no significant differences in STV for stair ascent between the pre- and post-operative visits, or compared to controls. There was a trend toward significance for the relationship between quadriceps strength and STV during stair ascent (P=0.059) and descent (P=0.073). Variability during stair stepping may provide an important, short-term rehabilitation target for individuals following TKA and may represent another parameter to predict declines in functional mobility.