Carol A. Oatis

Leg Motion Analysis During Gait by Multiaxial Accelerometry: Theoretical Foundations and Preliminary Validations

A theoretical formulation for studying limb motions and joint kinetics by multiaxial accelerometry is developed. The technique is designed to study the swing phase of human gait, modeling the lower leg as a rigid body. Major advantages of the approach are that acceleration information needed for the calculation of forces and moments is generated directly, and that the method automatically generates its own initial conditions. Results of validation experiments using both artificial and experimental data demonstrate that the method is theoretically valid, but that it taxes available instrumentation and requires further development before it can be applied in a clinical setting.

Patient-reported outcomes after total knee replacement vary on the basis of preoperative coexisting disease in the lumbar spine and other nonoperatively treated joints: the need for a musculoskeletal comorbidity index.

BACKGROUND Although the majority of patients report substantial gains in physical function following primary total knee replacement, the degree of improvement varies widely. To understand the potential role of preoperative pain due to other musculoskeletal conditions on postoperative outcomes, we quantified bilateral knee and hip pain and low back pain before primary total knee replacement and evaluated its association with physical function at six months after total knee replacement. METHODS A prospective cohort of 180 patients having primary unilateral total knee replacement reported joint-specific pain in right and left hips and knees (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] pain) as well as the low back (Oswestry Disability Index) before surgery. Participants also completed the Short Form-36 (SF-36), including the physical and mental component summary scores, before and at six months after surgery. RESULTS Of the 180 patients, 110 (61%) were women; the mean age was 65.1 years, the mean body mass index (BMI) was 32.5 kg/m², and mean SF-36 physical component summary score reported before the total knee replacement was 33.1. Before total knee replacement, 56.1% of the patients reported no or mild pain in the nonoperatively treated knee, hips, and low back. In addition, 22.2% of the patients had moderate to severe pain in one location; 12.8%, in two locations; and 8.9%, in three or four locations. Women reported more moderate to severe pain than men did in the nonoperatively treated knee (30% versus 11%; p < 0.004) and ipsilateral hip (26% versus 11%; p < 0.02). At six months, the mean physical component summary score was lower among patients with a greater number of preoperative locations of moderate to severe pain. After adjusting for age, sex, BMI, and SF-36 mental component summary score, moderate to severe preoperative pain in the contralateral knee (p = 0.013), ipsilateral (p = 0.014) and contralateral hip (p = 0.026), and low back (p < 0.001) was significantly associated with poorer function at six months after total knee replacement. CONCLUSIONS Preoperative musculoskeletal pain in the low back and nonoperatively treated lower extremity joints is associated with poorer physical function at six months after total knee replacement. The degree of functional improvement varies with the burden of musculoskeletal pain in other weight-bearing locations.

A randomized clinical trial of a peri-operative behavioral intervention to improve physical activity adherence and functional outcomes following total knee replacement

BackgroundTotal knee replacement (TKR) is a common and effective surgical procedure to relieve advanced knee arthritis that persists despite comprehensive medical treatment. Although TKR has excellent technical outcomes, significant variation in patient-reported functional improvement post-TKR exists. Evidence suggests that consistent post-TKR exercise and physical activity is associated with functional gain, and that this relationship is influenced by emotional health. The increasing use of TKR in the aging US population makes it critical to find strategies that maximize functional outcomes.Methods/DesignThis randomized clinical trial (RCT) will test the efficacy of a theory-based telephone-delivered Patient Self-Management Support intervention that seeks to enhance adherence to independent exercise and activity among post- TKR patients. The intervention consists of 12 sessions, which begin prior to surgery and continue for approximately 9 weeks post-TKR. The intervention condition will be compared to a usual care control condition using a randomized design and a probabilistic sample of men and women. Assessments are conducted at baseline, eight weeks, and six- and twelve- months. The project is being conducted at a large healthcare system in Massachusetts. The study was designed to provide greater than 80% power for detecting a difference of 4 points in physical function (SF36/Physical Component Score) between conditions (standard deviation of 10) at six months with secondary outcomes collected at one year, assuming a loss to follow up rate of no more than 15%.DiscussionAs TKR use expands, it is important to develop methods to identify patients at risk for sub-optimal functional outcome and to effectively intervene with the goal of optimizing functional outcomes. If shown efficacious, this peri-TKR intervention has the potential to change the paradigm for successful post-TKR care. We hypothesize that Patient Self-Management Support to enhance adherence to independent activity and exercise will enhance uniform, optimal improvement in post-TKR function and patient autonomy, the ultimate goals of TKR.Trial RegistrationClinicalTrials.gov: NCT00566826

Variations in Delivery and Exercise Content of Physical Therapy Rehabilitation Following Total Knee Replacement Surgery: A Cross-Sectional Observation Study.

Objective Prevalence of total knee replacement (TKR) is large and growing but functional outcomes are variable. Physical therapy (PT) is integral to functional recovery following TKR but little is known about the quantity or content of PT delivered. Purposes of this study were to describe the amount and exercise content of PT provided in the terminal episode of PT care following TKR and to examine factors associated with utilization and content. Methods Subjects included participants in a clinical trial of behavioral interventions for patients undergoing primary unilateral TKR who had completed the 6-month study evaluation. PT records were requested from 142 consecutive participants who had completed their post-TKR rehabilitation, 102 in/out patient care, and 40 in homecare. Information on utilization and exercises was extracted from a retrospective review of the PT records. Results We received 90 (88%) outpatient and 27 (68%) homecare PT records. Records showed variability in timing, amount and content of PT. Patients receiving outpatient PT had more visits and remained in PT longer (p<0.001). Exercises known in the TKR literature were utilized more frequently in the outpatient setting (p=0.001) than in home care. Records from both settings had limited documentation of strengthening progression. Conclusions The study reveals considerable variability in timing, utilization and exercise content of PT following TKR and suggests sub-optimal exercise for strengthening. While methods we employed document variability, improved systematic PT documentation and in-depth research are needed to identify optimal timing, utilization and content of PT following TKR.

Correlations among measures of knee stiffness, gait performance and complaints in individuals with knee osteoarthritis

BACKGROUND Stiffness is a common complaint in individuals with knee osteoarthritis and is a component of the osteoarthritis diagnosis. Yet the relationship between stiffness and function is poorly understood and methods to quantify stiffness are limited. METHODS Using a cross-sectional observational design with 66 subjects with knee osteoarthritis, stiffness and damping coefficients were calculated from a relaxed knee oscillation procedure. Gait parameters were measured using an electronic walkway. Self-reported pain, stiffness, and function were measured with the Western Ontario and McMaster Osteoarthritis Index. Correlation and Alexanders normalized-t approximation analyses were used to assess associations among the variables. Subset analysis was performed on subjects with and without tibiofemoral joint crepitus. FINDINGS Slight to moderate correlations existed between stiffness and damping coefficients and most gait parameters ((| r |=0.30-0.56; P<.05) and between Western Ontario and McMaster Osteoarthritis Index scores and all gait parameters (| r |=0.35-0.62; P<.05). The damping coefficient was only slightly associated with patient-rated Western Ontario and McMaster Osteoarthritis Index stiffness subscale scores. Subset analysis revealed significant correlations that differed between those with and without crepitus. INTERPRETATION These findings suggest that laboratory measured stiffness and damping coefficients, Western Ontario and McMaster Osteoarthritis Index scores and gait-related measurements assess different aspects related to movement in individuals with knee osteoarthritis. Stiffness and damping coefficients may offer the ability to explain gait changes in the knee that are independent of a persons perceptions particularly in the early stages of the disease.

Phase I design and evaluation of an isometric muscle reeducation device for knee osteoarthritis rehabilitation

Our long-term goal is to improve adherence to a home-based isometric program for rehabilitation of knee osteoarthritis (OA) using a force-biofeedback device (Isopad). Our goal for Phase I was to design and evaluate an Isopad-based program in a supervised clinical setting. Our subjects were five patients with knee OA of Kellgren stage II or greater. A capacitive force sensor was tested for accuracy, repeatability, and durability. An Arthritis Foundation home-based isometric program inspired the Isopad design. The Isopad provided visual and auditory feedback instantaneously and continuously about force generated between the ankles. The five subjects completed a supervised 8-week progressive isometric program using the Isopad. Absolute isolated quadriceps and hamstring torques were quantified with a dynamometer, and patients completed a self-assessment of symptoms (Western Ontario and McMaster Universities Osteoarthritis Index). The capacitive sensor accuracy error averaged 10% and repeatability 4%. Cognitively intact subjects used the Isopad successfully for isometric progressive resistance training. Quadriceps and hamstrings absolute torques increased an average of 30%. Patients reported decreased functional complaints (Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index). All changes were trends. The Isopad helped subjects with knee OA adhere to a supervised isometric program and meet progressive strength targets. The next-generation Isopad will be employed in a home-based program.

Neuromuscular and psychological influences on range of motion recovery in anterior cruciate ligament reconstruction patients.

To identify distinguishing characteristics for knee surgery patients who experience a protracted recovery process, we sought to determine if there is an association between the neuromuscular stretch reflex and psychological factors of pain perception and anxiety on the range of motion (ROM) recovery rate of post-operative anterior cruciate ligament reconstruction (ACLR) rehabilitation patients. The ACLR participants were categorized into a slow recovery group (SRG: >6 weeks to recover 0-125 degrees knee flexion [n=10]) and a normal recovery group (NRG: <6 weeks to recovery 0-125 degrees knee flexion [n=12]). Control participants (n=22) were age, gender and activity-level matched to the surgical participants. Neuromuscular testing consisted of sagittal plane video kinematics of the Wartenberg Pendulum Test for determining lower limb stiffness indices and electromyography-monitored patellar tendon tap reflex responses. Psychological and health status assessments consisted of the State-Trait Anxiety Inventory and SF-36 Health Survey. Data revealed that neuromuscular reflex profiles, lower limb stiffness indices, pain, anxiety and SF-36 indices of function were not significantly different between the two surgical groups (SRG and NRG). The surgical groups exhibited significantly greater pain (2.67+/-2.27 SRG, 1.49+/-1.15 NRG) than the control group (p.05). SF-36 indices were significantly lower for the surgical groups for total score (546.55+/-94.70 SRG, 577.57+/-125.58 NRG), function 69.00+/-20.24 SRG, 67.08+/-19.12 NRG), role physical (53.75+/-22.85 SRG, 53.12+/-23.15 NRG), social (76.24+/-25.31 SRG, 65.62+/-27.24 NRG), and emotional (82.49+/-19.81 SRG, 81.38+/-23.02 NRG) subscales (p.05). These results suggest that neuromuscular reflex responses, visual analogue scale (VAS) pain, and anxiety are not distinguishing factors for ROM recovery rate between the SRG and NRG. Decreased SF-36 indices, including pain as it influences function, though clinically relevant factors, were not statistically associated with post-operative ROM recovery rate.

Tailored system to deliver behavioral intervention and manage data in randomized trials.

Background The integrity of behavioral intervention trials depends on consistent intervention delivery, and uniform, comprehensive process data collection. It can be challenging in practice due to complex human interactions involved. Objective We sought to design a system to support the fidelity of intervention delivery and efficient capture of qualitative and quantitative process data for a telephone-delivered behavioral counseling intervention to increase physical activity and function after total knee replacement surgery. Methods A tailored system was designed to prompt the intervention coach in the delivery of a 5 step counseling protocol to support intervention fidelity across patients. System features included structured data components, automated data exchange functions, user-friendly data capture screens, and real-time surveillance reporting. The system structured the capture of patient goals and open-ended conversation. Results The system recorded intervention process data from each of 12 sessions held with the 92 intervention patients. During the trial, 992 telephone sessions were conducted, and more than 97% (4816/4960) of intervention process data fields were completed in the system. The coach spent 5-10 minutes preparing for each counseling call using system-generated summaries of historical data and 10-15 minutes entering intervention process data following each telephone session. Conclusions This intervention delivery system successfully supported the delivery of a structured behavioral counseling intervention and collection of intervention process data. It addressed the unique needs of clinical behavioral intervention trials, and had promising potential to facilitate high-fidelity translation of the intervention to broad clinical practice and Web-based multicenter clinical trials in the future.

Characteristics of Usual Physical Therapy Post-Total Knee Replacement and their Associations with Functional Outcomes

Although total knee replacement (TKR) surgery is highly prevalent and generally successful, functional outcomes post‐TKR vary widely. Most patients receive some physical therapy (PT) following TKR, but PT practice is variable and associations between specific content and dose of PT interventions and functional outcomes are unknown. Research has identified exercise interventions associated with better outcomes but studies have not assessed whether such evidence has been translated into clinical practice. We characterized the content, dose, and progression of usual post‐acute PT services following TKR, and examined associations of specific details of post‐acute PT with patients’ 6‐month functional outcomes.