Meniscal rim instability has a high prevalence and a variable location.

INTRODUCTION: Most classification systems for lateral discoid meniscus do not evaluate instability of the meniscal peripheral rim. Considerable variability in the prevalence of peripheral rim instability has been published, and it appears that instability is underestimated. The purpose of this study was: first, to evaluate the prevalence of peripheral rim instability and its location in the symptomatic lateral discoid meniscus, and second, to investigate if patient age or type of discoid meniscus are possible risk factors for instability. METHODS: A cohort of 78 knees that underwent operative treatment due to symptomatic discoid lateral meniscus was analyzed retrospectively for the rate and location of peripheral rim instability. RESULTS: Out of the 78 knees, 57.7% (45) had a complete and 42.3% (33) had an incomplete lateral meniscus. The prevalence of peripheral rim instability in symptomatic lateral discoid menisci was 51.3%, and with 32.5%, the anterior attachment was most commonly affected, followed by the posterior (30%) and central (10%) attachment. 27.5% of the tested menisci were unstable anteriorly and posteriorly. There was no significant difference in the prevalence of rim instability between the type of discoid menisci (complete vs. incomplete), nor was there a significant correlation for age as a risk factor for instability. CONCLUSION: The discoid lateral meniscus has a high prevalence and variable location of peripheral rim instability. Meniscal rim stability must be tested and addressed cautiously in all parts and in all types of discoid lateral menisci during operative treatment.

Elevated hip adduction angles and abduction moments in the gait of adolescents with recurrent patellar dislocation.

INTRODUCTION: Impaired hip kinematics and kinetics may incite patellar instability. This study tested the hypothesis that hip adduction and internal rotation angles during gait are higher in adolescents with recurrent patellar dislocations compared to healthy controls. MATERIAL AND METHODS: Case-control study. Eighty-eight knees (67 patients) with recurrent patellar dislocation (mean age 14.8 years ± 2.8 SD) were compared to 54 healthy knees (27 individuals, 14.9 years ± 2.4 SD). Peak hip, knee and pelvis kinematics and kinetics were captured using 3D-gait analysis (VICON, 12 cameras, 200 Hz, Plug-in-Gait, two force plates) and compared between the two groups. One cycle (100%) consisted of 51 data points. The mean of six trials was computed. RESULTS: Peak hip adduction angles and abduction moments were significantly higher in patients with recurrent patellar dislocation compared to the control group (p < 0.001 and 0.002, respectively). Peak internal hip rotation did not differ significantly. CONCLUSION: Elevated hip adduction angles and higher hip abduction moments in gait of adolescents with recurrent patellar dislocation may indicate an impaired function of hip abductors that contributes to patellar instability.

Does pathologically increased or decreased tibial torsion affect muscle activations during walking in typically developing adolescents?

A reduced capacity of plantar flexors and other muscles to extend the hip and knee during gait was shown in modelling studies when the tibial torsion angle is > 30° than normal. The aim of the current study was to determine if patients with increased or decreased tibial torsion show deviating muscle activations in knee and hip extensors in surface electromyography (EMG). Patients with CT confirmed increased tibial torsion (n = 19, ITT), decreased tibial torsion (n = 21, DTT) and age-matched healthy controls (n = 20) were included in this retrospective study. Additionally, kinematic and kinetic data were recorded during three-dimensional gait analysis. Surface EMG was recorded for vastus medialis and medial hamstrings. Statistical parametric mapping with a one-way ANOVA and post-hoc Bonferroni corrected two-sample t-tests were used to obtain differences in joint angles and moments. ITT and DTT showed an increased and decreased external foot progression angle, respectively. No additional muscle activations in vastus medialis and medial hamstrings were found in both patient groups compared to controls. DTT showed an increased hip flexion through parts of the gait cycle and both patient groups had a decreased knee extension moment in terminal stance. Our hypothesis of deviating muscle activation had to be rejected. It could be that in most orthopaedic patients the amount of exceeding tibial torsion is too low to cause substantial deviations in gait and muscle activation patterns.

Recurrent patellar dislocations in adolescents result in decreased knee flexion during the entire gait cycle.

PURPOSE: To evaluate the kinematics/kinetics of the ankle, knee, hip in the sagittal plane in adolescents with recurrent patellar dislocation in comparison to a healthy control. METHODS: Case-control study. Eighty-eight knees (67 patients) with recurrent patellar dislocation (mean age 14.8 years ± 2.8 SD) were compared to 54 healthy knees (27 individuals, 14.9 years ± 2.4 SD). Kinematics/kinetics of ankle, knee, hip, and pelvis were captured using 3D-gait analysis (VICON, 12 cameras, 200 Hz, Plug-in-Gait, two force plates). One cycle (100%) consisted of 51 data-points. The mean of six trials was computed. RESULTS: The loading-response increased by 0.02 s ± 0.01SE (10.8%) with dislocations (0.98% of total gait, P < 0.01). The mid-stance-phase decreased equally (P < 0.01). Dislocation decreased knee flexion during the entire gait cycle (P < 0.01), with the largest difference during mid-stance (9.0° ± 7.2 SD vs. 18.5° ± 6.7 SD). Dislocation increased plantar-flexion during loading response 4.1° ± 0.4 SE with (P < 0.01), afterward, the dorsal-extension decreased 3.2° ± 0.3 SE, (P < 0.01). Dislocation decreased hip flexion during all phases (P < 0.01). Maximal difference: 7.5° ± 0.5 SE during mid-stance. 80% of all patients developed this gait pattern. Internal moments of the ankle increased, of the knee and hip decreased during the first part of stance. CONCLUSION: Recurrent patellar dislocation decreases knee flexion during the loading-response and mid-stance phase. A decreased hip flexion and increased plantar-flexion, while adjusting internal moments, indicate a compensation mechanism. LEVEL OF EVIDENCE: III.

Trochleoplasty improves knee flexion angles and quadriceps function during gait only if performed bilaterally.

PURPOSE: To investigate if a trochleoplasty increases knee flexion angles and extensor moments in the gait of patients with patellar instability and to compare postoperative gait to a healthy control group. METHODS: A bilateral dislocation group (6 patients) and a unilateral dislocation group (14 patients) were treated with bilateral and unilateral trochleoplasty, respectively. Kinematics and kinetics of the lower extremity were captured using 3D-gait analysis (VICON, 12 cameras, 200 Hz, plug-in-gait, two force plates). The mean of six trials was computed. The gait cycles were compared pre to postoperatively for each group. The gait of the two groups was compared to each other and the gait of a healthy population (54 knees). RESULTS: After trochleoplasty, the knee flexion angles and knee extensor moments only increased in the bilateral dislocation group, whereas the gait pattern of the unilateral dislocation group remained unchanged. Compared to the healthy population, the postoperative gait pattern of the bilateral dislocation group did not differ. In contrast, knee flexion angles and extensor moments of the unilateral dislocation group were still lower. CONCLUSION: In adolescents with bilateral recurrent patellar dislocations, trochleoplasty of both knees increases knee flexion angles and knee extensor moments comparable to normal gait. Unilateral symptomatic patients undergoing a unilateral trochleoplasty did not achieve normal walking. These findings point out that patellar instability should be considered as a bilateral problem, even in patients with unilateral dislocations. LEVEL OF EVIDENCE: III.

Compensatory gait deviations in patients with increased outward tibial torsion pre and post tibial derotation osteotomy.

BACKGROUND: Tibial torsion describes the rotation between the proximal and distal joint axis along the shaft, which can be, as rotational deformity, pathologically increased or decreased. Some patients might increase hip internal rotation during walking to compensate increased outward tibial torsion. RESEARCH QUESTION: The aim of this study was to assess the effect of tibial derotation osteotomy on gait deviations in patients with increased outward tibial torsion. METHODS: Thirteen patients (13.5 ± 1.4 yrs, 22 limbs) with increased tibial torsion (CT confirmed 49.2 ± 4.8°) were analyzed pre and post tibial derotation osteotomy and compared with 17 typically developing children (TDC, 13.5 ± 2.3 yrs, 32 limbs). Kinematic and kinetic data were recorded. Subgroup analyses were performed whether patients showed compensatory hip internal rotation (Comp) or not (NoComp). Principal component (PC) analysis was used to achieve data transformation. A linear mixed model was used to estimate the main effect of PC-scores of retained PCs explaining 90% of the cumulative variance. RESULTS: Compensatory hip internal rotation (Comp, present in 45.5% of limbs analyzed) led to a lower external foot progression angle compared to patients without compensatory hip internal rotation (NoComp). In both patient groups foot progression angle was normalized after tibial derotation osteotomy. Post-operative NoComp had normalized frontal plane joint loadings, while Comp showed an increased hip and knee adduction moment. SIGNIFICANCE: Future studies should investigate if more time is needed for Comp to normalize gait patterns post-operative or if a pre and post-operative gait training might help. Otherwise the increased knee adduction moment might be clinically relevant due to previous studies reporting a possible association with knee osteoarthritis.

High failure rate 10.8 years after vastus medialis transfer and lateral release (Green's quadricepsplasty) for recurrent dislocation of the patella.

PURPOSE: In adolescent patients with recurrent patellar dislocation, the Green's quadricepsplasty stabilizes the patella in a combination of a lateral release, a transfer of the medial head of the quadriceps onto the lateral part of the patella and an imbrication of the medial patellar retinaculum and joint capsule. This study aimed to evaluate the long-term performance, considering re-dislocations and functional outcomes. We hypothesized a high failure rate in the long term. METHODS: In this single surgeon and single center study 26 knees in 23 patients (mean age 14.2 years; 4-22 years, 18 females) with recurrent patellofemoral dislocation underwent a vastus medialis transfer, medial reefing and lateral release as it was described by Green in 1965 with a mean follow-up 10.8 years (6-24 years). Clinical assessment was carried out with an IKDC-score (international knee documentation committee) and a self-assessment for each knee separately. The radiologic evaluation included measurement of the patella height, the grade of trochlear dysplasia and the sulcus angle. RESULTS: In 12 of 26 cases (46.2%) the patella did not re-dislocate after vastus medialis transfer and lateral release. In 11 of 26 cases (42.3%), the patients described the function of their knees as normal or nearly normal according to IKDC after the surgical treatment without any re-dislocation. In 14 of 26 cases (53.8%), the patella re-dislocated. 7 of these 14 cases underwent a revision operation. Re-dislocations occurred after a mean interval of 21 months after the index procedure. In only 2 of 26 cases (7.7%) the patients returned to sports. CONCLUSION: Green's procedure to stabilize patellofemoral instabilities results in a high failure rate on the long-term and low subjective assessments. We do not recommend performing vastus medialis transfer, medial imbrication and lateral release as a standalone technique. LEVEL OF EVIDENCE: IV.

The impact of increased femoral antetorsion on gait deviations in healthy adolescents.

Increased femoral antetorsion leads to several gait deviations, and amongst others, an increased knee flexion was reported in mid and terminal stance. Therefore, the purpose of this retrospective study was to identify gait deviations caused by increased femoral antetorsion and to perform subgroup analyses based on sagittal knee kinematics. Patients with isolated, CT confirmed increased femoral antetorsion (n = 42) and age-matched typically developing children (TDC, n = 17) were included in this study. Patients were referred to gait analysis because of gait abnormalities going along with an increased femoral antetorsion ≥30°. Kinematic and kinetic data were recorded during 3D gait analysis and three valid gait cycles were analyzed. Principal component (PC) analysis was used to achieve data transformation. A linear mixed model was used to estimate the group effect of PC-scores of retained PCs explaining 90% of the cumulative variance. Group effects of PC-scores revealed that patients walked with more flexed hips and greater anterior pelvic tilt throughout the gait cycle. Knee flexion was increased in patients during mid and terminal stance. Increased frontal plane knee and hip joint moments were found for patients compared to TDC. Furthermore, dividing patients into two subgroups based on their sagittal knee kinematics showed that kinematic gait deviations were more pronounced in patients with higher femoral antetorsion, while deviations in joint moments were more pronounced in patients with lower femoral antetorsion. Increased femoral antetorsion showed alterations in all lower limb joints and may be not only a cosmetic problem. Therefore, 3D gait analysis should be used for clinical management and operative treatment should be considered depending on severity of gait deviations.

Solitary Trochleoplasty for Treatment of Recurrent Patellar Dislocation.

BACKGROUND: Solitary trochleoplasty for recurrent patellar dislocation offers a unique benefit in that it addresses the most important factor in patellar instability: the trochlear dysplasia. DESCRIPTION: The trochlea is visualized through a lateral arthrotomy of the knee joint. An osteochondral layer is peeled off with curved chisels and extended into the intercondylar notch. A triangular bone block is removed from the subchondral bone to form the new groove. A new groove is begun with a chisel and smoothed with a high-speed burr. Also, the osteochondral layer is thinned out and fixed back transosseously in the new groove with 2 Vicryl (polyglactin) bands. The bone block is used to lengthen the lateral condyle by placing it under the osteochondral layer at the proximal extension of the lateral femoral condyle with an overlap of 1 cm. ALTERNATIVES: Nonsurgical alternatives include a knee or patellar brace, taping of the patella, and physiotherapy for strengthening of the vastus medialis obliquus of the quadriceps muscle. Surgical alternatives include reconstruction of the medial patellofemoral ligament; several femoral and tibial osteotomies, such as rotational osteotomies of the femur and tibia or medialization of the tibial tuberosity; and several soft-tissue interventions, such as medial reefing, relocation of the patellar tendon as described by Goldthwait1, and proximal realignments according to the method described by Insall et al.2 or Green et al.3. RATIONALE: Most patients with recurrent patellar dislocation have a dysplastic trochlea4, which is considered to be the primary reason for a recurrence. While interventions such as reconstruction of the medial patellofemoral ligament or femoral and tibial osteotomies also provide stability of the patella, they do not change the most essential factor of the instability-the trochlear dysplasia. The trochleoplasty addresses this underlying condition and reshapes the trochlea.

Development of VariLeg, an exoskeleton with variable stiffness actuation: first results and user evaluation from the CYBATHLON 2016.

BACKGROUND: Powered exoskeletons are a promising approach to restore the ability to walk after spinal cord injury (SCI). However, current exoskeletons remain limited in their walking speed and ability to support tasks of daily living, such as stair climbing or overcoming ramps. Moreover, training progress for such advanced mobility tasks is rarely reported in literature. The work presented here aims to demonstrate the basic functionality of the VariLeg exoskeleton and its ability to enable people with motor complete SCI to perform mobility tasks of daily life. METHODS: VariLeg is a novel powered lower limb exoskeleton that enables adjustments to the compliance in the leg, with the objective of improving the robustness of walking on uneven terrain. This is achieved by an actuation system with variable mechanical stiffness in the knee joint, which was validated through test bench experiments. The feasibility and usability of the exoskeleton was tested with two paraplegic users with motor complete thoracic lesions at Th4 and Th12. The users trained three times a week, in 60 min sessions over four months with the aim of participating in the CYBATHLON 2016 competition, which served as a field test for the usability of the exoskeleton. The progress on basic walking skills and on advanced mobility tasks such as incline walking and stair climbing is reported. Within this first study, the exoskeleton was used with a constant knee stiffness. RESULTS: Test bench evaluation of the variable stiffness actuation system demonstrate that the stiffness could be rendered with an error lower than 30 Nm/rad. During training with the exoskeleton, both users acquired proficient skills in basic balancing, walking and slalom walking. In advanced mobility tasks, such as climbing ramps and stairs, only basic (needing support) to intermediate (able to perform task independently in 25% of the attempts) skill levels were achieved. After 4 months of training, one user competed at the CYBATHLON 2016 and was able to perform 3 (stand-sit-stand, slalom and tilted path) out of 6 obstacles of the track. No adverse events occurred during the training or the competition. CONCLUSION: Demonstration of the applicability to restore ambulation for people with motor complete SCI was achieved. The CYBATHLON highlighted the importance of training and gaining experience in piloting an exoskeleton, which were just as important as the technical realization of the robot.

Operative treatment of congenital pseudarthrosis of the clavicle: a single-centre experience.

Congenital pseudarthrosis of the clavicle (CPC) is a very rare condition with a predilection for the right clavicle. Young children are often only symptomatic with activities and as they grow. Operative management in an asymptomatic child is debatable, with various techniques reported in the literature. This is a retrospective, single-centre case series study. All children with CPC treated surgically by resection, bone grafting (nonvascular iliac crest) and plate fixation between 2004 and 2012 at our centre were included. Excluded conditions were traumatic or obstetric fractures of the clavicle, children with musculoskeletal or neurological disorders and children lost to follow-up. Clinical and radiological examination was performed at 6 weeks, 3 months and between 6 and 12 months postoperatively. A total of eight clavicles in seven children (four girls and three boys), with a mean age of 7.1 years (5-8 years), were operated with a mean follow-up of 7 years (4-10 years). In six children, the right (dominant) side was affected, with one child affected bilaterally. Overall, 85% of our patients showed good functional results 6 weeks postoperatively and complete radiographic consolidation at a mean of 8.5 months (3-25 months) postoperatively. One female child showed delayed union, but without clinical deficit. There was low donor-site morbidity. We recommend early operative treatment of CPC with a nonvascularized bone graft from the iliac crest and plate fixation. LEVEL OF EVIDENCE: IV.

Increase in late diagnosed developmental dysplasia of the hip in South Australia: risk factors, proposed solutions.

OBJECTIVES: To review evidence for the increased incidence of late diagnosed developmental dysplasia of the hip (DDH) in South Australia; to identify perinatal risk factors associated with late DDH in babies born between 2003 and 2009 in SA. DESIGN: Linkage study of data collected prospectively by the South Australian Birth Defects Register (SABDR) and the Pregnancy Outcome Statistics Unit (SA Department of Health), supplemented by medical records review. PARTICIPANTS: All children born 2003-2009 in whom DDH was diagnosed between 3 months and 5 years of age and notified to the SABDR (data inclusion range, 2003-2014). Children with teratological hip dislocations and other major congenital abnormalities were excluded. MAIN OUTCOME MEASURES: Uni- and multivariable analyses were performed to identify perinatal risk factors for late diagnosed DDH. RESULTS: The incidence of late diagnosed DDH in babies born 2003-2009 was 0.77 per 1000 live births, contrasting with the figure of 0.22 per 1000 live births during 1988-2003. Significant perinatal risk factors were birth in a rural hospital (v metropolitan public hospital: odds ratio [OR], 2.47; CI, 1.37-4.46; P = 0.003), and being the second child (v being the first-born: OR, 1.69; CI, 1.08-2.66; P = 0.023). Breech presentation was highly significant as a protective factor when compared with cephalic presentation (OR, 0.25; CI, 0.12-0.54; P < 0.001). CONCLUSIONS: The incidence of late DDH has increased in SA despite an ongoing clinical screening program. Increased awareness, education, and avoidance of inappropriate lower limb swaddling are necessary to reverse this trend.