Introduction

Knee osteoarthritis (KOA) causes impairment through pain, stiffness and malalignment and knee joint replacement (KJR) may be necessary to alleviate such symptoms. There is disagreement whether patients with KJR increases their level of physical activity after surgery. The aim of this study is to investigate whether patients with KJR have a higher level of physical activity than patients with KOA, as measured by accelerometer-based method. Furthermore, to investigate whether patients achieve the same level of activity as healthy subjects five years post TJR.

The significance of physical activity (PA) assessment is widely acknowledged as it can aid in the understanding of pathologies. PA of knee osteoarthritis (KOA) patients has been assessed with varying methods, as it is a disease that is known to impair physical function and activity during daily life. Differences between methods have been described for general outcomes (sport participation or sedentary time), yet failed to describe common activities such as stair locomotion or sit-to-stand (STS) transfers. This study therefore aimed to determine the comparability of various methods to assess daily-life activities in KOA patients.

Sixty-one clinically diagnosed KOA patients wore a tri-axial accelerometer (AX3, Axivity, UK) for one week during waking hours. Furthermore, they performed three physical function tests: a 40-m fast-paced walk test (WT), a timed up-and-go test (TUGT) and a 15 stair-climb test (SCT). Patients were also asked to fill out the Knee Osteoarthritis Outcome Score (KOOS), a KOA-specific questionnaire.

Patients were slightly overweight (average BMI: 27.3±4.8 kg/m2), 60 (±10) years old and predominantly female (53%). The amount of daily level walking bouts was only weakly correlated with the WT performance, representing patients” walking capacity, (ρ=−0.33, p=0.01). Similarly, level-walking bouts during daily life correlated weakly with self-perceived walking capacity addressed by the KOOS (ρ=−0.36, p=0.01). For stair locomotion, a slightly different trend was seen. A moderate correlation was found (ρ=0.65, p<0.001), between the amount of ascending bouts and the objective functional test performance (SCT). However, the subjective assessment of stair ascending limitations (via the KOOS) correlated only weakly with both the functional test performance and the measured level of activity (ρ=−0.30 and −0.35, resp.). Comparable results were found for descending motions. STS transfers during daily life correlated moderately at best with the time to complete the TUGT (ρ=−0.43, p<0.01) and only weakly with the self-perceived effort of STS transfers (ρ=−0.26, p=0.04).

Only weak correlations existed between subjective measures and objective parameters (for both functional tests and daily living activities), indicating that they assess different domains (e.g. self-perceived function vs. actual physical function). Furthermore, when comparing the two objective measures, correlation coefficients increased compared to the subjective methods, yet did not reach strong agreement. These findings suggest that addressing common activities of daily life either subjectively or objectively will result in different patient-related outcomes of a study. Assessment methods should therefore be chosen with caution and compared carefully with other studies.

The medial patellofemoral ligament (MPFL) has been recognised as the most important medial structure preventing lateral dislocation or subluxation of the patella (LeGrand 2007). After MPFL rupture the patella deviates from the optimal path resulting in an altered retropatellar pressure distribution. This may lead to an early degeneration with loss of function and need for endoprosthetic joint replacement. The goal of this study was to develop a dynamic knee-simulator to test the influence of ligament instabilities to patella-tracking under simulation of physiological quadriceps muscle loading.

On 10 fresh-frozen cadaveric knees the quadriceps muscle was divided into five parts along their anatomic fibre orientation analogous to Farahmand 1998. The muscular loading was achieved by applying weights to each of the fife components in proportion to the cross sectional muscle area. A total of 175 N was connected to the muscles using modified industrial cable connecting systems [Lancier Calbe, Drensteinfurt/Germany].

A novel light digital patellar reference base (DRB) was developed and attached to the patella with four bone screws. On addition a femoral and tibial digital reference base was constructed and secured to these two bones.

Position data of the patella, the femur and tibia was tracked by a conventional tracking system [Optotrak, NDI Europe]. The relative movement between femur and tibia (“flexion path”) and patella and femur (“patella tracking”) was recorded. For retropatellar pressure measurement a custom made sensor was introduced between the patella and femur [Pliance, Novel/Germany]. The sensor consists of 85 single pressure measuring cells. The robot-control-unit is liked to a force-torque sensor (hybrid method). The force free knee-flexion-path from 0° to 90° was calculated during three “passive path” measurements using this hybrid robotic method. The actual measurements followed with identical parameters.

The 3D-patella position was recorded (six degrees of freedom) along with the corresponding retropatellar pressure distribution according to knee-flexion and medial forces (intact vs. cut MPFL). Measurements were performed for the intact knee (“native”), with muscular quadriceps loading, after opening the joint capsule and with introduced pressure sensor to differentiate each of their influences.

The load free knee-flexion-path (“passive path”) could be calculated for all of the ten knees and was utilised as the basis for all dynamic measurements. There was no alteration of the “flexion-path”. Thus the measurements were only influenced by the variables “capsular joint opening,” “muscular quadriceps loading” and “MPFL-tension”.

The custom made connections between the five quadriceps components and weights proved to be a secure way to prevent rupture due to the applied forces of up to 70 N during the average measuring time of 7.5 h/knee. Only on one knee the Vastus lateralis obliquus muscle ruptured proximally. All reference bases were 100% visible despite the knee flexion form 0°–90°. No loosening of the reference base screws occurred.

Overall the combination of a robotic-assisted, force free dynamic knee-flexion under quadriceps simulation and 3D-patella-tracking seems to be a promising method to evaluate the biomechanical influences of ligaments on the human knee.

Several studies report a diminished BMD as a consequence of childhood cancer treatment. The aim of this study was to investigate the effects of an exercise intervention on BMD during treatment, since limited mobility is characteristic for cancer therapy and is a major determinant for bone loss.

We analysed DXA scans (Lunar Prodigy, GE Healthcare) of 53 patients (range 8 to 21 years at time of diagnosis) perioperatively (n=49), six (n=38) and twelve months (n=18) after surgery. Scans were performed for the established sites of the lumbar spine and both femora, as well as experimentally for both calcanei. Areal BMD was corrected to obtain volumetric BMD using the model of Kröger.

For both groups, areal and calculated volumetric BMD values were similar at the lumbar spine at time of surgery, as were the differences between affected and not affected femur and calcaneus. The six and twelve months postoperative measurements revealed higher volumetric and areal BMD at the lumbar spine for the intervention group, although significant differences were only found for volumetric BMD values six months postoperatively.

Furthermore, a comparison of both groups showed that the loss in bone density of the affected lower extremity was less pronounced for the intervention group: differences between affected and not affected femur were 9% to 73% higher in the femur and 20% to 29% higher in the calcaneus for the control group.

Previous reports dealing with diminished BMD in pediatric cancer patients were confirmed in this study. However, differences found in BMD between both groups indicate that an exercise intervention during treatment, consisting primarily of strength and endurance training, may inhibit bone loss in pediatric sarcoma patients. Furthermore, the calcaneal site may be an alternative when the determination of femur BMD is not feasible.

Pediatric patients with lower extremity sarcoma often experience long lasting restrictions concerning physical activity and walking due to the required off-loading of the limb and other consequences of surgeries. Activity promotion during treatment in addition to physiotherapy could improve patients’ activity levels and walking capabilities.

In the present study we investigated the ambulatory activity of 31 pediatric patients (13.7 ± 3.1 years, 1.63 ± 0.15 m, 51.9 ± 15 kg, 19.3 ± 3.7 kg/m2) with Osteosarcoma or Ewing sarcoma at the lower limb using the StepWatch™ Activity monitor (SAM; Orthocare Innovations, USA). Sixteen patients regularly underwent supervised exercise interventions during inpatient stays, 15 did not receive any additional intervention. Step activities were measured for seven consecutive days during home stays at five different points in time, to determine a possible transfer of activity to everyday life.

Patients without intervention assembled considerably less steps than those in the intervention group. Before surgery they reached 25.4% of the intervention group (total n=16), six weeks after surgery 40% (total n= 8), after three months 46% (total n=10), after six months 72% (total n=13) and after one year 90%. However differences only reached significance at the first measurement.

Data presented must be considered as preliminary. Not all patients could be measured at all appointments due to impaired walking ability. Nevertheless activity promoting interventions during inpatient stays seem to have a positive influence on patients’ daily walking activity. Though the differences between the groups are not significant they are considerable. Especially during treatment – as reflected by the first three measurements- patients could benefit from additional interventions exceeding typical therapy regimes. Interventions should be individualized to the patients’ capabilities. Conclusions concerning tumor location or surgical procedures are not yet possible. Future research should furthermore concentrate on the effects of activity promotion on other fields of well-being.

Introduction: Mobile bearing total knee arthroplasty (TKA) has been developed to theoretically provide better, more physiological function of the knee and produce less PE wear. The theoretical superiority of mobile bearing TKAs over fixed bearing devices has not yet been proven in clinical studies. The objective of the present study was to prospectively analyze clinical and functional outcomes of randomized fixed and mobile bearing total knee arthroplasty patients by means of gait analysis, electromyography and established clinical scores.

Methods: In a prospective, randomized, patient- and observer-blinded, clinical study, 33 patients (mean age 63 years) received a cruciate retaining Genesis II TKA for primary osteoarthritis. 16 patients received a mobile bearing and 17 patients a fixed bearing device. The day before surgery and 24 months postoperatively, established clinical (KSS, HSS, WOMAC, UCLA, VAS) and quality of life (SF-36) scores were used to compare both patient groups. Electromyography of standardized locations was measured with the MyoSystem 2000 and analyzed with Myoresearch software. Gait analysis was performed with a six camera motion analysis system and force platforms.

Results: Both groups showed significant improvements between pre- and postoperative evaluation in gait analysis and electromyography, but gait analysis results as well electromyography did not show any difference between both groups at follow-up. Clinical and quality of life results significantly improved from pre- to postoperative evaluation, but only the Knee Society Score showed a significant superiority of the mobile bearing group (mean 159.0; SD 27.7; range, 105–196) over the fixed bearing group (mean 134.4; SD 41; range, 56–198) (p=0.0022).

Conclusions: In the present study, no functional advantage of mobile bearing TKA over fixed bearing devices could be found, although the mobile bearing group had better clinical results. Thus, long-term clinical results and in-vivo wear analyses have to be followed, and more subtle functional analyses (e.g. fluoroscopy) have to be employed to finally judge over the theoretical advantage of mobile bearing TKAs.

Aim of the Study: Evaluation of differences in pro-prioception, gait analysis, electromyography in consideration of clinical results in patients with unicondylar and bicondylar knee arthroplasty.

Material and Methods: 17 patients with mean age of 62.5 years were examined after a mean time of 21.5 months after unicondylar knee arthroplasty and compared with 15 patients with a mean age of 67 years and a mean time of 31.9 months after bicondylar knee arthroplasty. For clinical examination the Knee Society, Hospital for Special Surgery and Patella Score were used. Proprioception was examined using the Balance test. In addition each patient was examined by gait analysis with three-dimensional-kinematics and force plate. M. rectus femoris, M. vastus medialis/lateralis, M. semiten-dinosus, M. biceps femoris, M. tibialis anterior and M. gastrocnemius were examined by electromyography.

Results: There were neither significant deviations in demographic data, clinical scores, electromyography results (except M. vastus lateralis), gait analysis nor in proprioception.

Conclusion: There were no deviations in any clinical or functional results in patients with unicondylar and bicon-dylar knee arthroplasty. Because of the uncertain long term results of unicondylar knee arthroplasty in respect of loosening and development of contralateral osteoarthritis, bicondylar knee arthroplasty can be approved.

Aim: Evaluation of clinical, electromyographic and gait analysis results after constrained revision total knee arthroplasty. Material and Methods: 14 patients (mean age 67 years, 54-78) were evaluated 28.5 months (range, 6.5 to 61.4 months) after revision arthroplasty using constrained total knee endoprostheses (Genesis, Blauth).

Clinical evaluation was carried out using HSS, Knee Society, Tegner Activity, and Patellar scores. A three-dimensional, quantitative gait analysis and simultaneous epicutaneous electromyographic recordings of 7 muscles surrounding the knee were carried out on all patients. 11 healthy volunteers (mean age 69 years, 60-75) served as control group.

Results: Patients achieved 68 points in HSS, 125 in Knee Society, 1.3 in Tegner, and 19.1 in Patellar scores. Compared to the controls, all patients showed minor functional results. Electromyographic amplitudes of 5 muscles of the operated leg were significantly decreased compared to the contralateral side as well as the control group. Besides maximum knee extension all gait analysis parameters differed significantly between patients and controls. On the other hand, operated and uninvolved patients’ legs differed only in maximum knee extension in gait analysis. Significant correlations between clinical scores and ground reaction forces as well as electromyo-graphic levels of the gastroc muscle were noticed.

Conclusion: Functional deficits may not be explained by revision arthroplasty alone, but already exist preoperatively. The gastroc muscle seems to play and especially important role, as its functional deviations are highly correlated with clinical scores. The shown results stress the demand for extensive pre- and postoperative rehabilitation to avoid or at least reduce functional deficits after revision total knee arthroplasty.

To study the effect of ligament injuries and surgical repair we investigated the three-dimensional kinematics of the ankle joint complex and the talocrural and the subtalar joints in seven fresh-frozen lower legs before and after sectioning and reconstruction of the ligaments. A foot movement simulator produced controlled torque in one plane of movement while allowing unconstrained movement in the remainder.

After testing the intact joint the measurements were repeated after simulation of ligament injuries by cutting the anterior talofibular and calcaneofibular ligaments. The tests were repeated after the Evans, Watson-Jones and Chrisman-Snook tenodeses. The range of movement (ROM) was measured using two goniometer systems which determined the relative movement between the tibia and talus (talocrural ROM) and between the talus and calcaneus (subtalar ROM).

Ligament lesions led to increased inversion and internal rotation, predominantly in the talocrural joint. The reconstruction procedures reduced the movement in the ankle joint complex by reducing subtalar movement to a non-physiological level but did not correct the instability of the talocrural joint.

We report eight cases of fracture of the cuboid in seven children under four years of age, collected during a two-year period. There was no history of trauma in five of the patients. This fracture is rarely diagnosed and has probably been under-reported. Small children are poor historians and difficult to examine, and early radiographs may be normal or have only subtle abnormalities. Cuboid fracture should be considered in the differential diagnosis of limping toddlers, and a bone scan may be needed to confirm the diagnosis earlier than radiography. These fractures heal completely, without sequelae. Treatment in a short-leg walking cast is recommended, primarily for reasons of comfort.

We present the case of a 65-year-old man who developed a malignant fibrous histiocytoma at the lesser trochanter five months after a cementless hip replacement. We have reviewed reports of similar cases and discuss them in terms of the possible mechanisms of sarcomatous degeneration and the latency of such changes.