Hemiepiphysiodesis for Lower Extremity Coronal Plane Angular Correction in the Distal Femur and Proximal Tibia in Children With Achondroplasia.

BACKGROUND: Achondroplasia is the most prevalent form of skeletal dysplasia, affecting more than 250,000 individuals. Lower extremity angular deformities, particularly genu varum, are common in children with achondroplasia, often resulting in pain and limitation of function. The authors aim to determine the utility of lower extremity growth modulation with hemiepiphysiodesis in children with achondroplasia for correction of coronal plane deformities about the knee. METHODS: The authors performed a retrospective chart review of a single center from 1/1/2000 to 12/31/2020 to identify pediatric patients with achondroplasia treated with hemiepiphysiodesis as their initial procedure at the distal femur and/or proximal tibia. Patients with adequate records and who had completed their treatment were included. Data collected included duration of treatment, complications, need for osteotomy, and radiographic measurements including initial and final mechanical axis deviation, knee mechanical axis zone, mechanical lateral distal femoral angle and medial proximal tibia angle. RESULTS: Ten patients with 17 limbs met our criteria. Nine patients (15 limbs) were treated for genu varum and 1 patient (2 limbs) was treated for genu valgum. Prior to treatment, the mechanical axis fell in zone 3 in 59% of limbs and zone 2 in 41%. Average correction in mechanical axis deviation was 26.1 mm. Average change in mechanical lateral distal femoral angle was 10.3 degrees per limb, and average change in medial proximal tibia angle was 7.1 degrees per limb. Average treatment duration was 909 days. At final follow up, 81% (14/17) of limbs had the mechanical axis in zone 1, with the remaining 18% (3/17) in zone 2. No patient/limb underwent subsequent distal femur or proximal tibia osteotomy for coronal plane alignment. CONCLUSIONS: Children with achondroplasia can successfully be treated with hemiepiphysiodesis to correct coronal plane deformities at the distal femur and proximal tibia. Using this technique, no patient in our series required an osteotomy for genu varum/valgum. LEVEL OF EVIDENCE: Therapeutic level IV, Case series.

Prospective Study on Tension Band Plating: Most Patients are Not Returning to Normal Activities 1 Month Following Surgery.

BACKGROUND: Tension band plating for temporary hemiepiphysiodesis has been reported by several authors as simple and effective for treating angular deformities of the lower limb. Anecdotally, patients have reported higher pain levels than expected given the small size of incision and relatively minimal amount of dissection, and we sought to investigate this further. METHODS: Patients 16 years old or less with lower extremity angular deformities or limb length inequality were prospectively enrolled before tension band plating from 2 pediatric institutions from July 2016 to December 2018. Participants completed postoperative questionnaires regarding their pain and activity level. Pain was assessed using the FACES Pain Scale. Patients were included if they completed the 1 month survey. RESULTS: Of the 48 patients that met inclusion criteria (mean age at surgery: 13.1 y; range: 7 to 16 y), 39 patients completed the survey at 3 months postoperatively. There was a significant change in pain level between 1 week and 1 month postoperatively (P<0.001). Eighty-three percent (34/41) of patients were still taking pain medication at 1 week, which decreased to 38% (18/48) at 1 month. At 3 months, 21% (8/39) patients reported they were still using pain medication. At 1 month, 65% of patients (31/48) had not returned to their prior activity level. Of the 39 patients who played sports, 59% (23/39) still had not fully returned to sports at 1 month. CONCLUSION: At 1 month following tension band plating, 65% of patients had not returned to their preoperative activity level, and 38% were taking pain medications. Although the tension band plate and surgical incision is small in size, patients and parents should be counseled that there are significant activity limitations and pain levels for a month or longer in many patients. LEVEL OF EVIDENCE: Level II.

Supramalleolar osteotomy: a comparison of fixation methods.

BACKGROUND: For children with persistent tibial torsion, a wide variety of osteotomies and fixation methods have been proposed. We set out to compare the outcomes of percutaneous pin fixation versus a plate and screw construct. Our hypothesis was that the pin fixation group would have comparable outcomes without the need for a secondary procedure for implant removal. METHODS: A retrospective chart review was performed. Data were evaluated on patients undergoing a rotational supramalleolar osteotomy over a 10-year span with follow-up to union. Patient's age, underlying condition, degree of torsion, length of procedure, length of hospital stay, concomitant procedures, complications, recurrence, and secondary procedures were recorded. Statistical analysis utilized the Mann-Whitney U test for evaluation of independent samples. RESULTS: A total of 125 patients met the selection criteria with 186 tibias operated. Sixty-one cases were bilateral. Pin fixation was performed in 61 patients (87 tibias) and plate fixation in 64 patients (99 tibias). Age ranged from 2.5 to 19.6 (average 10.6) years. Surgical time, length of stay, and recurrence did not demonstrate a statistically significant difference between the pin fixation and the plate fixation groups. Forty-seven patients had secondary surgical procedures for removal of implants, 44 in the plate group and 3 in the pin group. Complications were considered major if they required reoperation or fracture care. In the plate group, 16 patients (12.8%) had complications with 5 major complications. In the pins group 3 patients (2.4%) had complications, which were minor. Recurrence was seen in 4 patients in the pin group and 2 patients in the plate group. Recurrence correlated with underlying neuromuscular disease and age younger than 11 years at the time of surgery. CONCLUSIONS: The numbers of complications, both major and minor, were significantly greater in the plate group. Therefore, the results of this study did not support our hypothesis that percutaneous pin fixation of supramalleolar osteotomies would have comparable outcomes to plate and screw fixation.

Drop landing analysis of rotational osteotomies.

Pathomechanics resulting from rotational deformities of the long bones in an idiopathic population have not been extensively studied, and are chiefly limited to level over ground walking. Thirty-five adolescents with excessive idiopathic outward tibial torsion (TT), femoral rotation, or both (pan genu) were studied both before and after corrective surgery. Data collected included computational motion analysis of a drop jump and patient-reported outcomes consisting of PODCI and Goal Attainment Scores. Results were compared to an age-matched typically developing cohort (n = 25). Subjects with femoral anteversion (FA) exhibited compensatory hip rotations to normalize knee progression angles at landing. Subjects with only TT did not compensate at the hip, landing with typical knee progression but excessive outward foot progression. These strategies resulted in elevated frontal plane knee moments for FA (P = 0.008), and elevated lateral knee forces in all groups compared to typical, with the TT group reaching significance (P < 0.001). Rotational osteotomies successfully restored elevated kinematics and kinetics to within or below typically developing ranges. Patient-reported outcomes generally improved after surgery across all domains studied. Drop jump testing elucidated compensation strategies employed by these cohorts. Compensation did not fully alleviate elevated forces at the knees. Surgical intervention normalized pathokinematics and pathokinetics, reduced pain, and improved patients' perception of their functional abilities. Greater improvements were found in individuals in the two groups with FA compared to the group with TT only.

Multilevel guided growth for hip and knee varus secondary to chondrodysplasia.

BACKGROUND: Young children with chondrodysplasia may develop multilevel varus deformities that compromise comfort and gait. The classic treatment of performing corrective, staged osteotomies, at each level of deformity, is a daunting prospect that is fraught with potential complications. To avoid this scenario, we have adopted single-event, multilevel surgery, using guided growth to simultaneously address bilateral varus deformities of the knee and hip, with good results. METHODS: Three cousins with Schmid-type metaphyseal dysplasia, presented for treatment of progressive varus deformities. In lieu of osteotomies, we used simultaneous guided growth of the proximal and distal lateral femora and proximal lateral tibiae, while ignoring the distal tibial deformity. The pan-genu 8-plates served to neutralize the mechanical axis while preserving a horizontal knee. The rationale for applying the trochanteric 8-plate was to stabilize the proximal femoral chondroepiphysis, hoping to postpone or avert intertrochanteric osteotomy. The average age at surgery was 28 months, with a range of 19 to 33 months, and follow-up has ranged from 28 to 59 months (average 48 mo). The pan-genu 8-plates were removed after an average of 12 months, leaving the trochanteric implants in situ, pending further growth. RESULTS: Neutralization of the mechanical axis resolved lateral knee thrust and intoeing. As the femur is effectively adducted by knee realignment, the greater trochanteric impingement on the ilium is alleviated. Lateral tethering of the trochanteric apophysis served to increase the femoral neck-shaft angle, improving the abductor lever arm. Each patient experienced complete resolution of the fatigue hip pain and Trendelenburg gait. As knee alignment was restored, the ankle varus resolved spontaneously, requiring no direct treatment. The clinical improvement was reflected in trending of the radiographic angles and axes toward normal. CONCLUSIONS: These children have benefited from outpatient guided growth, rather than the anticipated osteotomies, to correct multilevel varus deformities. Our goal is to exclusively use guided growth, repeatedly as needed, to avoid osteotomies altogether. Annual follow-up until skeletal maturity is planned. LEVEL OF EVIDENCE: Level IV-retrospective case series.

Experimental floral and inflorescence trait manipulations affect pollinator preference and function in a hummingbird-pollinated plant.

PREMISE OF THE STUDY: Controversy is ongoing regarding the importance of pollinator-mediated selection as a source of observed patterns of floral diversity. Although increasing evidence exists of pollinator-mediated selection acting on female reproductive success, there is still limited understanding of pollinator-mediated selection on floral traits via male reproductive success. Here we quantify potential selection by the ruby-throated hummingbird, Archilochus colubris, on four floral traits of hermaphroditic Silene exerted through male floral function. METHODS: In single trait manipulative experiments we quantified hummingbird visitation preference and/or fluorescent dye (a pollen analog) donation as a function of number of flowers displayed (inflorescence size), height of the floral display (inflorescence height), floral color, and corolla tube length. KEY RESULTS: Hummingbirds preferred to visit larger floral displays and floral displays at greater height, likely representing a general pollinator preference for larger, more visible signals and/or greater rewards. In addition, hummingbirds preferred to visit red flowers, and male function was greater in flowers manipulated to have longer corolla tubes. CONCLUSIONS: Selection pressures exerted by hummingbirds on S. virginica floral and inflorescence design through male reproductive success are consistent with the contemporary expression of floral traits of S. virginica relative to related Silene species with different pollinators, and they are consistent with the hummingbird syndrome of traits expressed by S. virginica.

Guided growth for ankle valgus.

BACKGROUND: Ankle valgus may be insidious and common in a variety of congenital conditions including clubfoot, neuromuscular disorders and others or acquired after fracture, osteotomies, or other manipulations of the lower extremity. This can cause hindfoot pronaton, resulting in lateral impingement and excessive shoe wear. Orthoses do not change the natural history. Medial hemiepiphysiodesis of the tibia is an accepted method of correcting this problem. Difficulties with transmalleolor screw removal prompted us to adopt the tension band method. Our purpose was to outline the technique of using guided growth with a medial tension band plate and discuss the efficacy of this technique. METHODS: We undertook this retrospective review of 33 patients (57 ankles) who underwent guided growth to correct ankle valgus and were followed until attaining full correction or skeletal maturity. Most of the implants were removed when the ankle was neutral to 5 degrees of varus overcorrection. We obtained weightbearing anteroposterior radiographs of the ankles preoperatively, just before plate removal, and at final follow-up, measuring the lateral distal tibial angle and noting the fibular station. We documented the rate of correction and related complications. RESULTS: The average age at surgery was 10.4 years (range, 6.1 to 14.6 y) and an average follow-up was 27 months (range, 12 to 57.5 mo). The lateral distal tibial angle improved from an average of 78.7 to 90 degrees at implant removal and measured 88.2 degrees at final follow-up. The rate of correction was calculated to be 0.6 degrees per month. The fibular station remained the same in 36 of 57 ankles and improved in 15 ankles. There were 2 cases of skin breakdown complicated by infection. There were no instances of hardware failure, excessive varus, or premature physeal closure and no patient has required an osteotomy. CONCLUSIONS: Without appropriate radiographs, ankle valgus may be mistaken for hindfoot valgus and mismanaged accordingly. Guided growth of the distal medial tibia has become our treatment of choice for ankle valgus in the growing child or adolescent. Use of plate epiphysiodesis is safe, well tolerated, may readily be combined with other treatments, and provides a rate of correction comparable to the transmalleolar screw method. LEVEL OF EVIDENCE: IV, retrospective review, no control series.

Initial stability of the acetabular fragment after periacetabular osteotomy: a biomechanical study.

BACKGROUND: Periacetabular osteotomy (PAO) has become the treatment of choice for skeletally mature patients with symptomatic acetabular dysplasia. Coincident with increasing use of PAO worldwide has been the introduction of various techniques for fixation of the acetabular fragment. Owing to the expanding indications for PAO, such as acetabular retroversion and femoroacetabular impingement, there is an increased interest in biomechanical data supporting the use of the varied acetabular fragment fixation techniques. Our study investigated the biomechanical strength of several PAO fixation techniques in vitro, including a novel plating technique. METHODS: PAO was performed on 17 artificial hemi-pelves with standardized biomechanical properties. Specimens were instrumented with the following constructs-3 screws from the iliac crest into the fragment (IS), 3 screws from the iliac crest and 1 transverse screw from the anterior inferior iliac spine into the sciatic buttress (IT), or 1 transverse screw with a contoured 3-hole plate across the iliac osteotomy (PT). The specimens were then loaded cyclically under compression and tension and to failure under tension in an material testing system through the anterior-inferior iliac spine. RESULTS: Data analysis with a single factor analysis of variance yielded mean loads-to-failure of 462 N for IS, 714 N for IT, and 817 N for PT (P=0.005). Further analysis using 2-sample t tests revealed that both IT and PT provided significantly higher loads-to-failure than IS (P=0.016 and P=0.0007, respectively). Under cyclic compression loading, the IT construct demonstrated decreased overall displacement when compared with IS (P=0.003). Under cyclic tension loading, PT achieved significantly smaller overall displacement than IS (P=0.007), as did IT when compared with IS (P=0.018). However, no significant difference was found between PT and IT (P=0.165) groups in cyclic loading or failure testing. CONCLUSIONS: Prior results showing improved performance of the IT construct have been replicated in a novel tension model. The novel plating technique provides greater load-to-failure than IS and is not inferior to IT. Both PT and IT allow significantly less displacement than IS in tensile and compressive cyclic loading. This novel technique may be easier to perform by surgeons in training or those new to the procedure. The results suggest a move beyond fixation solely with 3 antegrade screws. LEVEL OF EVIDENCE: Biomechanical study.