Kristoff Corten

An algorithm for the surgical treatment of periprosthetic fractures of the femur around a well-fixed femoral component

The use of plate-and-cable constructs to treat periprosthetic fractures around a well-fixed femoral component in total hip replacements has been reported to have high rates of failure. Our aim was to evaluate the results of a surgical treatment algorithm to use these lateral constructs reliably in Vancouver type-B1 and type-C fractures. The joint was dislocated and the stability of the femoral component was meticulously evaluated in 45 type-B1 fractures. This led to the identification of nine (20%) unstable components. The fracture was considered to be suitable for single plate-and-cable fixation by a direct reduction technique if the integrity of the medial cortex could be restored. Union was achieved in 29 of 30 fractures (97%) at a mean of 6.4 months (3 to 30) in 29 type-B1 and five type-C fractures. Three patients developed an infection and one construct failed. Using this algorithm plate-and-cable constructs can be used safely, but indirect reduction with minimal soft-tissue damage could lead to shorter times to union and lower rates of complications.

Gait alterations to effectively reduce hip contact forces

Patients with hip pathology present alterations in gait which have an effect on joint moments and loading. In knee osteoarthritic patients, the relation between medial knee contact forces and the knee adduction moment are currently being exploited to define gait retraining strategies to effectively reduce pain and disease progression. However, the relation between hip contact forces and joint moments has not been clearly established. Therefore, this study aims to investigate the effect of changes in hip and pelvis kinematics during gait on internal hip moments and contact forces which is calculated using muscle driven simulations. The results showed that frontal plane kinetics have the largest effect on hip contact forces. Given the high correlation between the change in hip adduction moment and contact force at initial stance (R2 = 0.87), this parameter can be used to alter kinematics and predict changes in contact force. At terminal stance the hip adduction and flexion moment can be used to predict changes in contact force (R2 = 0.76). Therefore, gait training that focuses on decreasing hip adduction moments, a wide base gait pattern, has the largest potential to reduce hip contact forces.

The Effectiveness of Preventive Programs in Decreasing the Risk of Soccer Injuries in Belgium National Trends Over a Decade

Background: Although characterized by a relatively high injury rate, soccer is the world’s most popular sport. In Belgium, the national Royal Belgian Football Association involves about 420,000 licensed players, whose injury reports are collected in a nationwide registry. Over a period of 10 years, the association has introduced the Fédération Internationale de Football Association preventive programs and has initiated a stringent postponement policy of competition in case of nonoptimal weather conditions. Hypothesis: The authors questioned whether these preventive programs effectively decreased the incidence of soccer-related injuries. Study Design: Descriptive epidemiology study. Methods: The authors compared the incidence, location, timing, and severity of all registered soccer injuries in Belgium during 2 complete seasons separated by a decade (1999-2000 vs 2009-2010). Results: A total of 56,364 injuries were reported, with an average of 6.8 injuries per 100 players per season. There was a 21.1% reduction in injury rate in the second season (rate ratio = 0.789; 95% confidence interval, 0.776-0.802), predominantly caused by a significant reduction in injuries during the winter period. In both seasons, an injury peak was noted during the first 3 months of the season. Recreational players had a higher risk for injury than national-level players (7.2 vs 4.4 injuries per 100 players per season; rate ratio = 1.64; 95% confidence interval, 1.59-1.69). The relative proportion of severe injuries was higher for female players and male youth players in general. Conclusion: The introduction of injury preventive programs has led to a significant reduction of soccer-related injuries, especially during the winter period. However, there is still room for improvement, and preventive programs can become more effective when specific parameters are targeted, such as adequate conditioning of players in the preseason.

Biomechanical gait features associated with hip osteoarthritis: Towards a better definition of clinical hallmarks.

Critical appraisal of the literature highlights that the discriminative power of gait‐related features in patients with hip osteoarthritis (OA) has not been fully explored. We aimed to reduce the number of gait‐related features and define the most discriminative ones comparing the three‐dimensional gait analysis of 20 patients with hip osteoarthritis (OA) with those of 17 healthy peers. First, principal component analysis was used to reduce the high‐dimensional gait data into a reduced set of interpretable variables for further analysis, including tests for group differences. These differences were indicative for the selection of the top 10 variables to be included into linear discriminant analysis models (LDA). Our findings demonstrated the successful data reduction of hip osteoarthritic‐related gait features with a high discriminatory power. The combination of the top variables into LDA models clearly separated groups, with a maximum misclassification error rate of 19%, estimated by cross‐validation. Decreased hip/knee extension, hip flexion and internal rotation moment were gait features with the highest discriminatory power. This study listed the most clinically relevant gait features characteristics of hip OA. Moreover, it will help clinicians and physiotherapists understand the movement pathomechanics related to hip OA useful in the management and design of rehabilitation intervention.

Incidence and risk factors of lower leg fractures in Belgian soccer players

INTRODUCTION Soccer is the worlds most popular sport and one that is physically demanding and highly competitive. Consequently, the rate of injuries resulting from this sport is only increasing. It is estimated that 2-20% of all such injuries are fractures, one-third of which are located in the lower extremities. The aim of this epidemiological study was to investigate the incidence of lower-leg fractures (LLFs) in Belgian soccer players and determine the possible risk factors that lead to them. METHODS All injuries of players associated with the Royal Belgium Football Association (RBFA) were reported and collected in a nationwide registry. We retrospectively compared the incidence rate of and risk factors for LLFs in Belgian soccer players during two seasons, 1999-2000 and 2009-2010. RESULTS In total, 1600 fractures (3%) were located in the lower leg. After a decade, the number of LLFs remained unchanged. Ankle fractures were the most common (37%), followed by foot and tibia fractures (33% and 22%, respectively). The least common were fibula fractures, which accounted for just 9%. A higher incidence of every type of LLF was observed in older and amateur-level soccer players, when compared with their younger and professional counterparts. Male players experienced more tibia and foot fractures, whereas the incidences of ankle and fibula fractures were comparable with those in female soccer players. The vast majority of fractures occurred during soccer games. CONCLUSION Ankle fractures and foot fractures represented two-thirds of all fractures noted in this analysis. Male gender, recreational level and adult age were important risk factors for LLFs. After 10 years, the incidence of LLFs did not decrease. Given the socioeconomic impact of these injuries, improved prevention techniques are required to reduce their incidence, particularly with regard to the frequently occurring ankle and foot fractures in this population.

Torsional injuries of the lower limb: an analysis of the frictional torque between different types of football turf and the shoe outsole

Background Football turf is increasingly used in European soccer competition. Little is known on the rotational torque that players experience on these fields. High rotational torques between the shoe outsole and the sports surface has been correlated with torsional injuries of the lower limb and knee. Purpose To evaluate the effect of six parameters that could influence the rotational torque between the shoe outsole and the latest generation football turf. Study design Controlled laboratory study. Methods A testing apparatus was constructed to measure the peak torque generated during a controlled rotation of the foot. Six parameters that could potentially influence the frictional forces, were considered: (1) the sports surface, (2) the shoe outsole cleat design, (3) the weather conditions, (4) the weight, (5) the presence of an impact and (6) the direction of rotation. Results The football turf without infill showed significantly lower frictional torques than natural grass whereas a football turf with sand/rubber infill had significantly higher torques. Blades were associated with significantly higher torques than studs on natural grass and on one football turf with sand/rubber infill. Dry weather was associated with higher torques only for the football turf without infill. The torque increased linearly and significantly with an increasing vertical load. The rotational torque increased significantly following an impact. Torques on external rotational movements were significantly higher with blades. Conclusions Important differences in rotational torques are found and could be seen as potential risk factors for torsional injuries of the lower limb.

Histologic Assessment of Acetabular Labrum Healing

PURPOSE The purpose of this study was to histologically examine the human healing response of arthroscopically repaired acetabular labrum tears. METHODS Biopsy specimens were retrieved from 6 patients during total hip arthroplasty after clinical failure of the index arthroscopic procedure. All patients were diagnosed as having femoroacetabular impingement with a concomitant labral tear. In all cases severe chondral damage was observed during arthroscopy (Beck grades 3 to 4). Despite successful technical repair of the labral tear, chondral damage in these patients was so advanced that the clinical progress after the procedure was unsatisfactory and arthroplasty of the joint was required. Biopsy specimens of the repaired acetabular labra were harvested during the arthroplasty surgery and processed for standard histologic evaluation. RESULTS Macroscopically and histologically, all repaired labra kept their triangular shape more or less and appeared to have healed. All harvested biopsy specimens displayed a typical fibrocartilaginous appearance with limited vascular supply. Calcifications were present in only 1 biopsy specimen. In 3 cases neovascularization of the labral tissue was noticed in the proximity of the sutures. In the superficial and deep parts of the labral body, small clefts were observed in all cases. CONCLUSIONS In this study the histologic aspects of arthroscopically repaired human labral tears were addressed. It was shown that human labral tears show healing potential after surgical repair. The surfaces of the labral tissues were intact, and neither remnants of the tear nor the presence of fibrovascular scar tissue was observed. However, some small clefts in the superior and deep parts of the repaired structures were noticed in all cases. LEVEL OF EVIDENCE Level IV, therapeutic case series.

Test-Retest Reliability of Innovated Strength Tests for Hip Muscles

The burden of hip muscles weakness and its relation to other impairments has been well documented. It is therefore a pre-requisite to have a reliable method for clinical assessment of hip muscles function allowing the design and implementation of a proper strengthening program. Motor-driven dynamometry has been widely accepted as the gold-standard for lower limb muscle strength assessment but is mainly related to the knee joint. Studies focusing on the hip joint are less exhaustive and somewhat discrepant with regard to optimal participants position, consequently influencing outcome measures. Thus, we aimed to develop a standardized test setup for the assessment of hip muscles strength, i.e. flexors/extensors and abductors/adductors, with improved participant stability and to define its psychometric characteristics. Eighteen participants performed unilateral isokinetic and isometric contractions of the hip muscles in the sagittal and coronal plane at two separate occasions. Peak torque and normalized peak torque were measured for each contraction. Relative and absolute measures of reliability were calculated using the intraclass correlation coefficient and standard error of measurement, respectively. Results from this study revealed higher levels of between-day reliability of isokinetic/isometric hip abduction/flexion peak torque compared to existing literature. The least reliable measures were found for hip extension and adduction, which could be explained by a less efficient stabilization technique. Our study additionally provided a first set of reference normalized data which can be used in future research.

Does surgical approach or prosthesis type affect hip joint loading one year after surgery

Several approaches may be used for hip replacement surgery either in combination with conventional total hip arthroplasty (THA) or resurfacing hip arthroplasty (RHA). This study investigates the differences in hip loading during gait one year or more after surgery in three cohorts presenting different surgical procedures, more specific RHA placed using the direct lateral (RHA-DLA, n=8) and posterolateral (RHA-PLA, n=14) approach as well as THA placed using the direct anterior (THA-DAA, n=12) approach. For the DAA and control subjects, hip loading was also evaluated during stair ascent and descent to evaluate whether these motions can better discriminate between patients and controls compared to gait. Musculoskeletal modelling in OpenSim was used to calculate in vivo joint loading. Results showed that for all operated patients, regardless the surgical procedure, hip loading was decreased compared to control subjects, while no differences were found between patient groups. This indicates that THA via DAA results in similar hip loading as a RHA via DLA or PLA. Stair climbing did not result in more distinct differences in hip contact force magnitude between patients and controls, although differences in orientation were more distinct. However, patients after hip surgery did adjust their motion pattern to decrease the magnitude of loading on the hip joint compared to control subjects.

Subject-specific musculoskeletal modelling in patients before and after total hip arthroplasty*

Abstract The goal of this study was to define the effect on hip contact forces of including subject-specific moment generating capacity in the musculoskeletal model by scaling isometric muscle strength and by including geometrical information in control subjects, hip osteoarthritis and total hip arthroplasty patients. Scaling based on dynamometer measurements decreased the strength of all flexor and abductor muscles. This resulted in a model that lacked the capacity to generate joint moments required during functional activities. Scaling muscle forces based on functional activities and inclusion of MRI-based geometrical detail did not compromise the model strength and resulted in hip contact forces comparable to previously reported measured contact forces.