Knee rotationplasty: motion of the body centre of mass during walking

Progress in muscle strength of the reconstructed knee and quality of life of the patient after knee rotationplasty: A case report

Knee rotationplasty (KRP) is a function-preserving surgery that serves as an alternative to above-knee amputation in patients diagnosed with malignant bone and soft tissue tumors around the knee joint. However, the short-term progress of the reconstructed knee in terms of muscle strength is unclear after KRP. This case report describes the progress of a 37-year-old man diagnosed with synovial sarcoma in the distal femur, 1 year after undergoing KRP. Changes in muscle strength of the reconstructed knee and physical function are reported. Physical therapy was started on postoperative day 1 after the KRP, and mobilization proceeded step-by-step with sitting, wheelchair transfer, and crutch walking. Active and passive range-of-motion exercises of the reconstructed knee were started on postoperative day 5. The isometric reconstructed knee extension strength, 10-m walk test, timed up and go test, Musculoskeletal Tumor Society score, Toronto Extremity Salvage Score, and quality of life (QOL) were evaluated. One month postoperatively, muscle strength had increased, and at 6 and 12 months postoperatively, isometric knee extension strength and physical function had improved. Furthermore, activities of daily living and QOL gradually improved over the course of the 12 months. Our case shows the previously unknown course of reconstructed knee muscle strength in the early post-KRP period, with corresponding improvements in physical function, activities of daily living, and QOL.

A New Quantitative Gait Analysis Method Based on Oscillatory Mechanical Energies Measured near Body Center of Mass

Human locomotion involves the modulation of whole-body mechanical energy, which can be approximated by the motion dynamics at the body’s center of mass (BCOM). This study introduces a new method to measure gait efficiency based on BCOM oscillatory kinetic energy patterns using a single inertia measurement unit (IMU). Forty-seven participants completed an overground walk test at a self-selected speed. The average oscillatory energy (OE) at BCOM during walking was derived from measured acceleration data. The total OE showed a positive correlation with forward-walking velocity. The ratio of total OE to constant forward kinetic energy for healthy adults varied from ~1−5%, which can be considered the percent of oscillatory energy required to maintain gait posture for a given forward-walking velocity. Mathematically, this ratio is proportional to the square of the periodic peak-to-peak displacement of BCOM. Individuals with gait impairments exhibited a higher percentage of oscillatory energy, typically >6%. This wearable IMU-based method has the potential to be an effective tool for the rapid, quantitative assessment of gait efficiency in clinical and rehabilitation settings.

Dynamic Asymmetries Do Not Match Spatiotemporal Step Asymmetries during Split-Belt Walking

While walking on split-belt treadmills (two belts running at different speeds), the slower limb shows longer anterior steps than the limb dragged by the faster belt. After returning to basal conditions, the step length asymmetry is transiently reversed (after-effect). The lower limb joint dynamics, however, were not thoroughly investigated. In this study, 12 healthy adults walked on a force-sensorised split-belt treadmill for 15 min. Belts rotated at 0.4 m s−1 on both sides, or 0.4 and 1.2 m s−1 under the non-dominant and dominant legs, respectively. Spatiotemporal step parameters, ankle power and work, and the actual mean velocity of the body’s centre of mass (CoM) were computed. On the faster side, ankle power and work increased, while step length and stance time decreased. The mean velocity of the CoM slightly decreased. As an after-effect, modest converse asymmetries developed, fading within 2–5 min. These results may help to decide which belt should be assigned to the paretic and the unaffected lower limb when split-belt walking is applied for rehabilitation research in hemiparesis.

The curvature peaks of the trajectory of the body centre of mass during walking: A new index of dynamic balance

During walking, falling is most likely to occur towards the side of the supporting lower limb during the single stance. Timely lateral redirection of the centre of mass (CoM) preceding the no-return position is necessary for balance. We analysed the curvature peaks (the inverse of the radius of curvature) of the three-dimensional path of the CoM during the entire stride. Twelve healthy adults walked on a force-sensorized treadmill at constant velocities from 0.4 to 1.2 m s^-1, in 0.2 m s^-1 increments. The three-dimensional displacements of the CoM, the muscular power sustaining the CoM motion with respect to the ground, and the efficiency of the pendulum-like transfer of the CoM were computed via the double integration of the ground reaction forces. The curvatures of the CoM trajectory were measured (Frenet-Serret formula). During the single stance, the curvature showed a bell-shaped increment, lasting a few tenths of a millisecond, and peaking at 365-683 m^-1 (radius of 2.7-1.4 mm, respectively), the higher the walking velocity. The CoM was redirected towards the swinging lower limb. The curvature increment was sustained by muscle-driven braking of the CoM. Smoother increments of curvature (peaking at approximately 37-150 m^-1), further orienting the CoM towards the leading lower limb, were observed during the double stance. The peaks of the curvatures were symmetric between the two sides. The high curvature peaks during the single stance may represent an index of dynamic balance during walking. This index might be useful for both rehabilitation and sports training purposes.

[Rotationplasty in a schoolboy for osteosarcoma: Prosthesis fitting and update]

INTRODUCTION

The classical treatment of osteosarcoma used to be ablative surgery. After the appearance of adjuvant chemotherapy, survival in these patients increased, and with it, the number of affected school age children with high growth potential. Hence, reconstructive surgeries are currently proposed instead of conventional bone resections due to greater limb preservation and better functional status than those achieved with conventional amputations.

CASE PRESENTATION

We describe a case of osteosarcoma in a 9-year-old boy with a history of retinoblastoma. The tumour involved the entire length of the left femur. He also had a lung metastasis. Given the incomplete response to neoadjuvant chemotherapy, we chose bone resection, rotation and fitting of the left lower limb and thoracoscopy to treat the lung injury. A bypass ortoprosthesis was placed for the first 6 weeks, until there was healing, bone consolidation and absence of complications, followed by a definitive orthoprosthesis for the next 4 months. At one year, the patient was able to walk independently with the use of the ortoprosthesis, swimming with a fin adapted to the stump and was had restarted cycling. At the last clinical review, at the age of 13 years, he is disease free and continues to have periodic follow-up visits in our office for adaptations to the prosthesis according to his growth.

DISCUSSION

This case highlights the various reconstructive options available and the difficulties encountered in the management of these aggressive malignant processes. Rotationplasty is a viable therapeutic option in young patients with osteosarcoma, which allows the child to participate again in premorbid daily and recreational activities.

[Application of rotationplasty in treatment of osteosarcoma of distal femur in children]

Objective

To investigate the effectiveness of rotationplasty in treating osteosarcoma of distal femur in children.

Methods

A clinical data of 10 children with osteosarcoma of distal femur treated with rotationplasty between March 2014 and June 2016 was retrospectively analyzed. There were 7 boys and 3 girls with an average age of 6.7 years (range, 4-10 years). There were 4 cases of osteoblastic osteosarcoma, 4 cases of mixed osteosarcoma, and 2 cases of chondroblastic osteosarcoma. All children were staged as Enneking stage ⅡB. The disease duration ranged from 3.5 to 6.0 months (mean, 4.6 months). The lower limb functional scoring system of 1993 Musculoskeletal Tumor Society (MSTS93), Toronto Extremity Salvage Score (TESS), and knee mobility were used to evaluate postoperative function. Tumor recurrence and metastases were monitored by radiograph.

Results

Poor superficial incision healing occurred in 1 patient, and healed after dressing change. The other incisions healed by first intention. All children were followed up 24-72 months (mean, 52.6 months). No local recurrence was observed during follow-up. Three of the ten patients suffered from metastases including 1 dying of multiple organ dysfunction syndrome, 1 alive with tumor, and 1 tumor free survival. Painful callosities and ulcers which related to prosthetic wear occurred in 2 patients and turned up after optimizing prosthetic fit and physiotherapy. The fracture healing time was 2.5-5.0 months (mean, 3.5 months). All children could walk independently at 4 months postoperatively. At last follow-up, the MSTS93 score was 19-25 (mean, 22) and the TESS score was 87-93 (mean, 90). The extension of knee joint mobility with artificial limbs was 0°-10° (mean, 5°), and the flexion of knee joint mobility with artificial limbs was 85°-95° (mean, 90.5°).

Conclusion

Rotationplasty in treating osteosarcoma of distal femur in children with limb salvage difficulties can effectively preserve the limb function and improve the quality of life, and it can be used as an alternative to amputation.

Does Osteoarthritis of the Ipsilateral Hip Develop After Knee Rotationplasty? A Radiologic Study on Patients with Long-term Survival Undergoing Surgery for Bone Tumors

BACKGROUND

During routine check-ups of long-term surviving knee rotationplasty patients referred to our institute, we noted that the operated limb radiograph showed signs of hip osteoarthritis in some patients, and that one patient reported hip pain. We wondered whether radiographic changes and symptoms are common in patients undergoing rotationplasty due to mechanical or overloading problems during gait. Based on these considerations, we wished to determine how frequently arthrosis or arthritis would arise in the ipsilateral hip to a knee rotationplasty at long-term follow-up. To our knowledge, this issue has not been explored. Clinicians and patients should be aware of any problems that may affect the hip over time that could result in treatment.

QUESTIONS/PURPOSES

At a minimum of 10 years after rotationplasty, in a single-center series, we therefore asked: (1) What proportion of patients reported hip pain at rest and with activity? (2) What proportion have radiographically visible arthritic changes in the ipsilateral or contralateral hip? (3) What proportion of patients have changes in the hip morphology (femoral rotation, cervicodiaphyseal angle, acetabular angle, osteopenia)?

METHODS

Between 1986 to 2009, 42 patients underwent rotationplasty in our institute. They represent the 16.5% of a series of 254 children (age 3 to 14 years) affected by high-grade bone sarcomas located in the distal half of the femur. Three more patients were adolescents older than 15 years and were treated with rotationplasty because of the tumor volume and extracompartmental involvement. Of these 45 patients, 14 died of disease at a mean of 37 months; 31 patients were survivors at the time the study was done. Three of these long-term survivors were known to be alive but did not come for a clinic visit in the last 5 years. The remaining 28 patients were invited to participate in a research study on the long-term assessment of rotationplasty, and all agreed to participate. Unfortunately, 10 patients living far from our Institute could not come in the 2 days established for the assessment due to family or work constraints. AP plain radiographs of the pelvis were taken in 17 patients with long-term survival after knee rotationplasty. Patients were positioned in a standard weightbearing position, wearing their own prosthesis. Hip osteoarthritis was assessed using the Croft grading system. The presence of hip pain was assessed with the self-reported Numeric Rating Scale (NRS), with scores ranging from 0 to 10, at rest and during daily life activities. Femoral rotation, osteopenia, the cervicodiaphyseal and the acetabular angles were measured on radiographs. The median (range) age at follow-up was 32 years (22 to 45), the median age at the time of the intervention was 9 years (6 to 17), and the median follow-up duration after surgery was 25 years (11 to 30).

RESULTS

One of the 17 patients complained of mild pain (NRS score of 2) in the ipsilateral hip during walking. No other patient claimed to have hip pain at rest or during walking or other daily life activities. Eleven of 17 patients had signs of OA according to the Croft grading system: one had Grade 1 OA, seven had Grade 2, and three had Grade 3. Six patients did not show any sign of OA in the ipsilateral hip. Two patients had Grade 1 OA and one had Grade 2 OA of the contralateral hip. Sixteen patients had femoral external rotation. An increased valgus cervicodiaphyseal angle and acetabular angle were present in 10 and 9 patients, respectively. Osteopenia at the ipsilateral hip when compared with the contralateral, was present in all patients but one, with varying degrees of severity.

CONCLUSIONS

In this small series, signs of osteoarthritis of the hip ipsilateral to the rotationplasty were present in a high proportion of patients at a minimum follow-up interval of 10 years after surgery, although only one participant reported hip pain. The finding of arthrosis in the hip above a rotationplasty is potentially important because it may be related to gait abnormalities that may modify the hip's morphology over time. It is encouraging that symptomatic hip pain was uncommon in our patients, but this could become more of a clinical problem with longer follow-up and result in therapeutic intervention. Patients (or the parents of patients) undergoing this procedure should be informed that they might develop hip arthritis during young adulthood.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Rehabilitation and Prosthetic Design after Van Nes Rotationplasty of the Left Leg Due to Severe Burn Contractures in a Patient with Contralateral Amputated Right Femur: A Case Report

Background:

Van Nes Rotationplasty (VNRP) is a biological reconstructive surgical method for pediatric sarcoma, complex trauma or severe lower limb deficiencies that often gets overlooked due to cosmetic reasons and psychological aspects. We report a unique case of knee stiffness and severe scarring from burns treated with this technique in a young patient who had also amputated contralateral femur.

Case Report:

A 15-year-old boy was trapped in a fire 10 years ago and sustained extensive contractures on his left knee due to severe burns and also an above knee amputation on his right thigh. For 10 years the boy had never received rehabilitation or worn any prosthesis and he managed to move bearing mainly on his palms. On admission to our hospital Van Nes rotationplasty was preferred among other treatment options as the most suitable solution for him and was successfully performed without complications.

The patient had severe stiffness on his right hip and decreased muscle power in the VNRP leg but after intensive physiotherapy he was able to stand upright and walk again using custom made bilateral prostheses and crutches.

Conclusion:

VNPR is a reasonable option in severe contractures and scarring of the knee joint.

Limping on split-belt treadmills implies opposite kinematic and dynamic lower limb asymmetries

Walking on a split-belt treadmill (each of the two belts running at a different speed) has been proposed as an experimental paradigm to investigate the flexibility of the neural control of gait and as a form of therapeutic exercise. However, the scarcity of dynamic investigations challenges the validity of the available findings. The aim of the present study was to investigate the dynamic asymmetries of lower limbs of healthy adults during adaptation to gait on a split-belt treadmill. Ten healthy adults walked on a split-belt treadmill mounted on force sensors, with belts running either at the same speed ('tied' condition) or at different speeds ('split' condition, 0.4 vs. 0.8 or 0.8 vs. 1.2 m/s). The sagittal power and work provided by ankle, knee and hip joints, joint rotations, muscle lengthening, and surface electromyography were recorded simultaneously. Various tied/split walking sequences were requested. In the split condition a marked asymmetry between the parameters recorded from each of the two lower limbs, in particular from the ankle joint, was recorded. The work provided by the ankle (the main engine of body propulsion) was 4.8 and 2.2 times higher (in the 0.4 vs. 0.8, and 0.8 vs. 1.2 m/s conditions, respectively) compared with the slower side, and 1.2 and 1.1 times higher compared with the same speed in the tied condition. Compared with overground gait in hemiplegia, split gait entails an opposite spatial and dynamic asymmetry. The faster leg mimics the paretic limb temporally, but the unimpaired limb from the spatial and dynamic point of view. These differences challenge the proposed protocols of split gait as forms of therapeutic exercise.

Postural control skills, proprioception, and risk of fall in long-term survivor patients treated with knee rotationplasty

Knee A1 rotationplasty is a particular type of limb salvage surgery alternative to hip disarticulation and high transfemoral amputation for skeletally immature children with bone cancers in the distal femur. Notwithstanding optimal functional outcomes, long-term survivor patients often report frequent falls, and a sense of instability during gait, particularly on uneven terrain. This study aimed to assess the postural control, the proprioception, and the risk of fall in these patients, which have not been explored before. Eighteen long-term survivor patients participated in the study. The mean follow-up from surgery was 23 years, mean age 32 years. Patients were assessed using a specific instrumental device (Delos Postural Proprioceptive System) both for the static double-stance and the single-stance test in the open eyes and closed eyes conditions. The double-stance test showed postural instability values within the normal range for healthy individuals, whereas in the single-stance test stability index, when assessed in the average of both lower limbs, values were lower than the literature findings for older individuals. However, when separating the operated from the nonoperated limb performance, standing on the operated limb was very unstable, with a low stability index and a low degree of autonomy, indicating a certain risk of falling, whereas standing on the nonoperated limb had a performance close to normal or even superior. In conclusion, knee rotationplasty patients had very good postural control when standing on both limbs, whereas single stance on the operated limb was compromised, with particular involvement of the proprioceptive component. This may determine a higher risk of falling than their normal-age counterparts and rehabilitation intervention for prevention is indicated.

Gait analysis on force treadmill in children: comparison with results from ground-based force platforms

Gait analysis (GA) typically includes surface electromyographic (sEMG) recording from several lower limb muscles, optoelectronic measurement of joint rotations, and force recordings from ground-based platforms. From the latter two variables, the muscle power acting on the lower limb joints can be estimated. Recently, gait analysis on a split-belt force treadmill (GAFT) was validated for the study of adult walking. It showed high reliability of spatiotemporal, kinematic, dynamic, and sEMG parameters, matching those obtainable with GA on the basis of ground walking. GAFT, however, still needs validation in children. Potential differences with respect to adult GAFT relate to (a) possible high signal-to-noise ratio, given the lower forces applied; (b) higher differences between treadmill and over-ground walking; and (c) limited compliance with the experimental setup. This study aims at investigating whether GAFT provides results comparable with those obtainable from ground walking in children and consistent with results from GAFT in adults. GAFT was applied to three groups of healthy children aged 5-6 years (n=6), 7-8 years (n=6), and 9-13 years (n=8) walking at the same average speed spontaneously adopted overground. The results were compared with those obtained from another study applying GA to an age-matched and speed-matched sample of 47 children, and with those obtained from GAFT in adults. The reliability (as indicated by the SD) of both spatiotemporal and dynamic parameters was higher in GAFT compared with GA. In the 5-6-, 7-8-, and 9-13-year-old groups, at average speeds of 0.83, 1.08, and 1.08 m/s, step length was shorter by 9.19, 3.57, and 2.30% compared with GA in controls at comparable speeds, respectively. For the youngest group, a lower power generation from the plantar flexors (peak power: 1.35±0.32 vs. 2.11±1.02 W/kg) and a slightly more flexed posture of the hip, knee, and ankle joints were observed during GAFT compared with GA in controls. The other gait parameters were very similar between the GAFT and the GA groups. The shortening of step length during GAFT, relative to GA at superimposable speed, was on average of all children 6.8%, in line with the 8% decrease found in adults. The profiles of sEMG and joint rotations, and all of the weight-standardized joint power parameters, matched those recorded in adults. The entire experimental session lasted about 1 h. All children complied with the experimental setting and easily completed the requested tests. In conclusion, GAFT seems to be a promising alternative to conventional GA in children.

Crouch gait can be an effective form of forced-use/no constraint exercise for the paretic lower limb in stroke

In hemiplegic gait the paretic lower limb provides less muscle power and shows a briefer stance compared with the unaffected limb. Yet, a longer stance and a higher power can be obtained from the paretic lower limb if gait speed is increased. This supports the existence of a ‘learned non-use’ phenomenon, similar to that underlying some asymmetric impairments of the motion of the eyes and of the upper limbs. Crouch gait (CG) (bent-hip bent-knee, about 30° minimum knee flexion) might be an effective form of ‘forced-use’ treatment of the paretic lower limb. It is not known whether it also stimulates a more symmetric muscle power output. Gait analysis on a force treadmill was carried out in 12 healthy adults and seven hemiplegic patients (1–127 months after stroke, median: 1.6). Speed was imposed at 0.3 m/s. Step length and single and double stance times, sagittal joint rotations, peak positive power, and work in extension of the hip, knee, and ankle (plantar flexion), and surface electromyography (sEMG) area from extensor muscles during the generation of power were measured on either side during both erect and crouch walking. Significance was set at P less than 0.05; corrections for multiplicity were applied. Patients, compared with healthy controls, adopted in both gait modalities and on both sides a shorter step length (61–84%) as well as a shorter stance (76–90%) and swing (63–83%) time. As a rule, they also provided a higher muscular work (median: 137%, range: 77–250%) paralleled by a greater sEMG area (median: 174%, range: 75–185%). In erect gait, the generation of peak extensor power across hip, knee, and ankle joints was in general lower (83–90%) from the paretic limb and higher (98–165%) from the unaffected limb compared with control values. In CG, peak power generation across the three lower limb joints was invariably higher in hemiparetic patients: 107–177% from the paretic limb and 114–231% from the unaffected limb. When gait shifted from erect to crouch, only for hemiplegic patients, at the hip, the paretic/unaffected ratio increased significantly. For peak power, work, sEMG area, and joint rotation, the paretic/unaffected ratio increased from 55 to 85%, 56 to 72%, 68 to 91%, and 67 to 93%, respectively. CG appears to be an effective form of forced-use exercise eliciting more power and work from the paretic lower limb muscles sustained by a greater neural drive. It also seems effective in forcing a more symmetric power and work from the hip extensor muscles, but neither from the knee nor the ankle.