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.

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.

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.

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.

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.