Recovery of the medial gastrocnemius muscle after calcaneus fracture differs between contractile and elastic components.

BACKGROUND: Calcaneal fractures result in severe functional impairments and walking restrictions. Postoperative evaluation mainly focusses on the restoration of calcaneal anatomy while ankle plantar flexor insufficiency remains largely neglected. This study aims to investigate biomechanical and morphologic adaptions of elastic and contractile components of the gastrocnemius medialis after unilateral calcaneal fracture. METHODS: 20 Patients (BMI: 27.6 ± 3.1 kgm-2, Age: 50 ± 12 years) were measured using gait analysis and portable ultrasound over a follow-up of three, six and twelve months after surgery. Data comparison was performed using 20 matched healthy controls (BMI: 26.2 ± 2.9 kgm-2, Age: 48 ± 11 years). Static and dynamic behavior of the gastrocnemius muscle tendon unit, muscle fascicle and the serial-elastic element as well ankle joint kinematics and kinetics were analyzed. FINDINGS: Within patients, a significant (p < 0.05) increase in fascicle length (by 67%) during single support and a decrease of serial elastic element shortening (by 20%) during push off was found between three and twelve months follow-up comparisons. Patients showed differences for fascicle lengthening and pennation angle increase during single support after three and six months compared to healthy controls. A smaller shortening of the serial-elastic element (by 29%) and muscle-tendon unit (by 16%) persisted even for the twelve month comparisons. INTERPRETATION: Patients with calcaneal fracture showed an incomplete restoration of the medial gastrocnemius dynamic morphological behavior. While muscle fascicle contraction almost recovered, the serial elastic component still showed restrictions regarding its shortening behavior. Limited foot mobility and plantarflexor strength as well as lowered responsiveness of elastic tissues to mechanical loading are regarded as key mechanisms.

Development of the center of pressure velocity in the healing process after intra-articular calcaneus fractures.

BACKGROUND: Calcaneal fractures are among the most common foot injuries and sometimes develop manifold post-surgical complications. Restricted foot movement is one of the main functional limitations which often persists during long-term rehabilitation. Therefore, it is important to quantitatively monitor the biomechanical foot mobility after calcaneal fracture from an early stage in order to achieve an optimal therapeutic treatment. RESEARCH QUESTION: Evaluation of the Center of Pressure velocity (vCOP) in patients after intrarticular calcaneal fractures during the healing progress from three to 24 months after surgery. METHODS: A total of 20 patients with unilateral calcaneal fracture were investigated by means of pedobarography and marker-based gait analysis at three, six, 12 and 24 months after surgery. Data for vCOP [m/s], maximum external dorsal extension moments during stance (DEmomentstance) and tibiotalar range of motion during mid stance (MS) and terminal stance (TS) were obtained. Functional evaluation was performed using clinical examination (e.g. calf circumference measurements) and patient-reported outcome measures (SF-36). RESULTS: When compared to the healthy side, vCOP of the injured side showed a significant reduction during MS (3 months: 48%, p < 0.001; 6 months: 13%; p = 0.040) and an significant increase during TS (3 months: 110%, p < 0.001; 6 months: 43%, p < 0.001; 12 months: 17%, p = 0.012). DEmomentstance of the fractured foot, showed a significant increase of 80% (p < 0.001) from three to 24 months after surgery, which correlated with vCOP at three and six months after surgery (p < 0.05; vCOP MS: 3 months: r = 0.876, 6 months: r = 0.685; vCOP TS: 3 months: r = -0.554, 6 months r = -0.626). SIGNIFICANCE: vCOP might serve as an indicator for foot mobility and function during the early healing phase after calcaneal fractures. As vCOP can be obtained by pedobarography it is more readily accessible an less costly compared to foot function obtained by marker based gait analysis.

Gait characteristics and functional outcomes during early follow-up are comparable in patients with calcaneal fractures treated by either the sinus tarsi or the extended lateral approach.

BACKGROUND: To overcome the substantial functional loss after calcaneal fractures (CF), surgical treatment currently consists of two strategies, namely the commonly used extended lateral approach (ELA) and the less invasive sinus tarsi approach (STA). Despite the comparable anatomical restoration, the biomechanical and functional outcome of these strategies during early rehabilitation has not yet been investigated. RESEARCH QUESTION: To evaluate changes in gait characteristics and functional development in patients with CF treated by either STA or ELA. METHODS: A total of 56 patients with unilateral CF were included in this retrospective study. 26 patients were treated by ELA while 30 patients underwent surgery through the STA. Functional and biomechanical measurements were performed at follow-up periods of three and six months. Foot and ankle kinetics and kinematics were extracted using instrumented gait analysis with a multi segment foot model. Physical and mental components of the Short Form 36 (SF-36) and total scoring of the AOFAS hindfoot scale were used for functional evaluation. Statistical analysis was performed using Mann Whitney and Student's t-test. Effect sizes of group differences were calculated using Cohen's d. RESULTS: Comparisons between ELA and STA showed no significant difference regarding the biomechanical and functional outcome. Within-group comparisons showed significant (p < 0.05) improvements from three to six month follow-up. Ankle joint and hindfoot kinematics showed increased mobility during walking of up to 34% and 26%, respectively. Maximum ankle joint moment also improved by up to 34% while vertical ground reaction force increased by 8%. Functional outcome only revealed significant changes in the physical component of SF-36. SIGNIFICANCE: ELA and STA treatments revealed comparable functional improvements in patients with unilateral intraarticular calcaneal fractures during early rehabilitation. The less invasive STA provides adequate restoration of dynamic foot function and could serve as a viable alternative to the commonly used ELA.

Auxiliary locking plate improves fracture stability and healing in intertrochanteric fractures fixated by intramedullary nail.

BACKGROUND: Intertrochanteric fractures present a significant management challenge due to their low inherent stability. The objective of this study was to determine whether an auxiliary locking plate decreases interfragmentary motions and improves fracture healing in intertrochanteric fractures treated by intramedullary nail. METHODS: Biomechanical tests and a clinical retrospective study in intertrochanteric to subtrochanteric nonunions were performed. Six synthetic femurs were osteotomized intertrochanterically and fixated with a long gamma nail and an additional locking compression plate. Mechanical tests were conducted that simulated the hip joint force during gait cycle. Following the initial test, the locking compression plate (LCP) was removed from each specimen and the test was repeated. Interfragmentary motions, strains on implants and osteosynthesis stiffness were determined. For the clinical part of the study, 13 intertrochanteric to subtrochanteric nonunions were treated with revisional long gamma nail and additional locking compression plate. Complications and time to union were determined. FINDINGS: Biomechanically, interfragmentary rotation was 48% smaller (P=0.047) and interfragmentary shear movement was 42% smaller (P=0.007) with locking compression plate. Strains on the nail decreased by 20-27% (P<0.027) and the osteosynthesis stiffness increased by 23% (P=0.005) with locking compression plate. Clinically, fracture healing was achieved in eleven out of 13 patients after 9.0months (range 4 to 22months). INTERPRETATION: The findings of our study indicate that auxiliary locked plating considerably improves biomechanical performance and results in successful healing of unstable intertrochanteric to subtrochanteric femur fractures.