Lateral Distal Femur Research Articles

A Ramped Administration of Pamidronate in Children: Preliminary Results

Introduction Pamidronate is the most widely used bisphosphonate to treat osteoporosis in children. It is commonly given IV for 3 consecutive days, for 5 orHtreatment fractures occur at the margins of pamidronate bands that form with bisphosphonate treatment in growing bone. A ramped dosing regimen was proposed to mediate stress-riser formation. Objectives Compare the effects of a ramped dosage schedule of pamidronate on BMD, fracture rate and location versus a uniform 5-course regimen. Methods Ten non-ambulatory children (7 females) with neuromuscular disabilities who received IV pamidronate with a tapering dose were identified (Group 1) and compared to a cohort of 25 similar patients who received a uniform 5-course regimen (Group 2). Periodic DXA evaluations were performed every 6 months. Fracture rate before and after treatment was calculated using the person-years method, with post-treatment observation starting with the first dose. Radiographs were examined for location of fracture. Results Over treatment, lumbar spine (LS) BMD increased 47.7% and lateral distal femur (LDF) BMD of all regions (R1, R2 & R3) increased 38.0%, 30.1%, and 22.9%, respectively. Group 2 BMD increases were 40.3% at LS and 68.3%, 15.6% and 10.8%, for LDF R1 – R3. Mean post-treatment observation period was 4.6 years. Two of 10 children in Group 1 sustained a fracture during treatment [right distal femur at 3 weeks, left foot at 10.5 months] but no fractures occurred after treatment ended. Pre and post-treatment fracture rates were 18.5% and 4.3%. Four of 25 in Group 2 sustained 5 fractures after treatment over the same time period; 80% occurred at pamidronate bands. Pre and post-treatment fracture rates in were 36% and 13% for Group 2. Conclusion Regardless of dosing schedule, BMD improved, post-treatment fracture rate decreased after treatment started, and fractures occurred during treatment. After treatment ended, no fractures occurred in those who received the ramped dosage, suggesting reduction in stress riser formation. A longer treatment period and greater total amount of drug administered with the ramped dose might be contributory. Further study of a ramped dosing schedule is warranted.

Single cut distal femoral osteotomy for correction of femoral torsion and valgus malformity in patellofemoral malalignment - proof of application of new trigonometrical calculations and 3D-printed cutting guides

BackgroundThe purpose of this study was to perform a derotational osteotomy at the distal femur, as is done in cases of patellofemoral instability, and demonstrate the predictability of three-dimensional (3D) changes on axes in a cadaveric model by the use of a new mathematical approach.MethodsTen human cadaveric femurs, with increased antetorsion, underwent a visually observed derotational osteotomy at the distal femur by 20°, as is commonly done in clinics. For surgery, a single cut osteotomy with a defined cutting angle was calculated and given using a simple 3D-printed cutting guide per specimen, based on a newly-created trigonometrical model. To simulate post-operative straight frontal alignment in a normal range, a goal for the mechanical lateral distal femur angle (mLDFA) was set to 87.0° for five specimens (87-goal group) and 90.0° for five specimens (90-goal group). Specimens underwent pre- and post-operative radiographic analysis with CT scan for torsion and frontal plane x-ray for alignment measurements of mLDFA and anatomical mechanical angle (AMA).ResultsPerformed derotation showed a mean of 19.69° ±1.08°SD (95% CI: 18.91° to 20.47°). Regarding frontal alignment, a mean mLDFA of 86.9° ±0.66°SD (87-goal-group) and 90.42° ±0.25° SD (90-goal group), was observed (p = 0.008). Overall, the mean difference between intended mLDFA-goal and post-operatively achieved mLDFA was 0.14° ±0.56° SD (95% CI: -0.26° to 0.54°).ConclusionA preoperative calculated angle for single cut derotational osteotomy at the distal femur leads to a clinically precise post-operative result on torsion and frontal alignment when using this approach.

Transient retrograde interfragmentary compression technique in AO/OTA type 33-C distal femur fractures: A surgical technique and short-term radiographic follow up results

Surgical treatment of AO/OTA type 33-C fractures is a therapeutic challenge despite advances in surgical instruments and techniques. We introduce a novel surgical technique named transient retrograde interfragmentary compression (TRIC) to help intraarticular fragment reduction in AO/OTA type 33-C fracture. We inserted a partial threaded 7.0-cannulated screw with a washer along the transepicondylar axis from the medial femoral epicondyle during the articular block reduction process of AO/OTA type 33-C fractures to strengthen the compressive force between the condylar fragments and to enhance the handling of the articular block fragment in the alignmental correction stage. Following the provisional reduction and fixation using lateral distal femur locking compression plate, TRIC screw was removed. Fifteen AO/OTA type 33-C distal femoral intraarticular fractures of thirteen patients were surgically treated using the TRIC technique. We analyzed the radiographic result of the patients by measuring the horizontal gap and vertical step-off in the postoperative radiographs. Mean horizontal fracture gap was 0.34 mm and mean vertical step-off between bicondylar fragments was 0.63 mm. The median value of the horizontal fracture gap and vertical step off was 0 and 0.46 mm, respectively. Mean time to union in the bicondylar fracture fragment was 9 week. TRIC is considered to be a valuable surgical reduction technique in the treatment of the AO/OTA 33-C type fractures.

Comparison of fluoroscopic techniques for assessment of femoral rotational alignment

Objectives:Anatomic rotational reduction of diaphyseal femur fractures is essential in restoring limb mechanics. Errors in reproducing anteroposterior (AP) or lateral knee reference radiographs of the contralateral limb could result in inaccuracies during rotational reduction. The objective of this study was to examine whether fluoroscopic rotational variation can be observed with the same degree of precision with AP and lateral distal femur projections.Methods:AP and lateral radiographs were obtained from intact knees of 7 cadaveric specimens using fluoroscopy. The lateral condylar width and coronal femoral width from the AP images and the posterior condylar offset and sagittal femoral width from the lateral images were measured by 3 reviewers. Interclass correlation coefficients (ICCs) among the 3 reviewers were calculated. The mean data from all reviewers were plotted against angle of rotation, and the slope (M) and regression of the line were then determined.Results:ICCs were 0.997 (lateral) and 0.994 (AP), demonstrating excellent interobserver agreement. The mean (±SD) M value for lateral images was 0.016 ± 0.001 and for AP images was 0.009 ± 0.001 (P < .0001). The higher lateral M value represents a more appreciable difference in size of the measured segment for the same rotational change.Conclusions:The observed rotational change was 1.76 times greater on lateral images compared to AP images; thus, the lateral images may be more precise as a reference for rotation. The routine use of lateral knee radiographs to guide intraoperative rotational alignment of the femur may therefore be justified.

Surgical treatment for knee osteoarthritis subsequent to previous femur fractures

Objective To investigate the indications and clinical outcomes of total knee arthroplasty or osteotomy for knee osteoarthritis subsequent to previous femur fractures. Methods Six patients (three male and three female) with knee osteoarthritis subsequent to previous femur fractures were analyzed retrospectively between February 2006 and February 2017. The average age of patients was 58.2±10.3 years old, ranged from 51 to 79 years. Four patients underwent total joint replacement and two underwent osteotomy. The average age of patients in joint replacement group was 60.5±12.3 years old. The age of the two patients in the osteotomy group was 51 and 55 years old, respectively. The extra-articular deformity angle of the coronal plane of the femur, lateral distal femur angle of mechanical axis, hip-knee-ankle angle (HKA) of preoperative and postoperative were determined on long-standing radiography. The mean angle of the extra-articular deformity in the joint replacement group was 17.0±7.7 degrees. The angle of the extra-articular deformity in the osteotomy group was 34 and 20 degrees. Lateral distal femur angle of mechanical axis in the joint replacement group was within the range of 87±7 degrees. Lateral distal femur angle of mechanical axis in the osteotomy group was out of the range of 87±7 degrees. The mean preoperative HKA of the joint replacement group was 161.8±8.0 degrees. The preoperative HKA of the osteotomy group was 155 and 160 degrees, respectively. Knee function was estimated according to knee range of motion and Knee Society Score (KSS). The results of postoperative hip-knee-ankle angle, knee range of motion (ROM) and knee society score were compared between the two groups. Results The mean HKA of the joint replacement group reached 176.0±2.8 degrees at one year postoperatively. The HKA of the osteotomy group improved to 177 and to 175 degrees at one year postoperatively. The average preoperative knee ROM improved significantly from 71±16 degrees preoperatively to 113±5 degrees postoperatively. The mean knee ROM of the joint replacement group was 113.0±6.8 degrees. The knee ROM of two patients in the osteotomy group was 110 and 115 degrees, respectively. The average preoperative KSS score improved significantly from 46±3 preoperatively to 88±3 postoperatively. The mean KSS of the joint replacement group was 88.8±3.0, while the KSS of the osteotomy group was 85 and 82. No bone nonunion was observed in the two patients in osteotomy group. Conclusion For patients with knee osteoarthritis subsequent to previous femur fractures, satisfactory short-term clinical outcomes could be obtained by total knee arthroplasty or osteotomy with the strict selection of proper operative indications. Key words: Femoral fractures; Osteoarthritis; Arthroplasty, replacement, knee

Magnetic resonance imaging and spectroscopy evidence of efficacy for adrenal and gonadal hormone replacement therapy in anorexia nervosa.

Dehydroepiandrosterone (DHEA)+estrogen/progestin therapy for adolescent girls with anorexia nervosa (AN) has the potential to arrest bone loss. The primary aim of this study was to test the effects of DHEA+estrogen/progestin therapy in adolescent girls with AN on bone marrow in the distal femur using magnetic resonance imaging (MRI) and spectroscopy. Seventy adolescent girls with AN were enrolled in a double blind, randomized, placebo-controlled trial at two urban hospital-based programs. Seventy-six girls were randomly assigned to receive 12months of either oral micronized DHEA or placebo. DHEA was administered with conjugated equine estrogens (0.3mg daily) for 3months, then an oral contraceptive (20μg ethinyl estradiol/ 0.1mg levonorgestrel) for 9months. The primary outcome measure was bone marrow fat by MRI and magnetic resonance spectroscopy (MRS). T2 of the water resonance dropped significantly less in the active vs. placebo group over 12months at both the medial and lateral distal femur (p=0.02). Body mass index (BMI) was a significant effect modifier for T1 and for T2 of unsaturated (T2unsat) and saturated fat (T2sat) in the lateral distal femur. Positive effects of the treatment of DHEA+estrogen/progestin were seen primarily for girls above a BMI of about 18kg/m2. These findings suggest treatment with oral DHEA+estrogen/progestin arrests the age- and disease-related changes in marrow fat composition in the lateral distal femur reported previously in this population.

Chronic lateral epiphyseal separation of the proximal tibia causes late-onset tibia vara

An adolescent obese boy showed late-onset unilateral tibia vara associated with physeal separation (slipped epiphysis) of the lateral proximal tibia and physeal widening of the lateral distal femur. These affected physes showed normal signal intensities by MRI. He was treated with lateral hemiepiphysiodesis of the left proximal tibia and the distal femur using two parallel eight-Plates, and varus deformity rapidly improved postoperatively without recurrence. This is the first case of late-onset tibia vara caused by lateral physeal separation of the proximal tibia. Normal growth of the medial physes around the knee would contribute toward significant correction after surgery.

Validation of Body Composition Measures From Forearm and Lateral Distal Femur Scans of Children

Validation of Body Composition Measures From Forearm and Lateral Distal Femur Scans of Children

Hologic Horizon Spine, Forearm and Lateral Distal Femur Precision in Young Children

Hologic Horizon Spine, Forearm and Lateral Distal Femur Precision in Young Children

P.14 - Testosterone therapy in patients with Duchenne muscular dystrophy and glucocorticoid-induced pubertal delay

Glucocorticoid therapy slows disease progression in Duchenne muscular dystrophy (DMD), but causes significant adverse effects, including delayed puberty or hypogonadism, obesity, insulin resistance and osteoporosis. Lack of puberty or hypogonadism further increases risk for osteoporosis and affects quality of life, but is not consistently addressed in DMD care. We sought to determine if testosterone therapy could induce puberty, and to examine the effects of testosterone therapy on body composition, bone health and metabolic indices, in glucocorticoid-treated patients with DMD. We reviewed medical records of boys with DMD on long-term glucocorticoid therapy, who were treated with testosterone for delayed (n = 31) or arrested (n = 2) puberty. Outcomes of interest were endogenous pubertal development; changes in body composition; bone mineral density and content of lumbar spine, whole body and lateral distal femur by dual-energy X-ray absorptiometry; and metabolic laboratory indices. Changes in bone health measures within 2.5 years prior to treatment were compared to changes up to 2.5 years after treatment initiation. Thirty-three male patients (median age 15.0 years, 27% ambulatory) on glucocorticoid therapy (median duration 7.7 years) were treated with testosterone therapy for a median of 37 (range 4.1 to 73.5) months. Endogenous puberty developed in 45% of previously pre-pubertal boys after starting testosterone. We observed increases in spine and whole body absolute bone mineral content (p = 0.03 and 0.0002 respectively), and stabilization of fat mass and percentage of total body fat accrual, when comparing post- to pre-testosterone treatment initiation. Although longer-term data are needed, testosterone therapy should be considered in the management of glucocorticoid-treated male patients with DMD who experience delayed puberty.

Normative data for lateral distal femur bone mineral density in children from 3 to 18 years of age using Lunar Prodigy absorptiometry

Normative data for lateral distal femur bone mineral density in children from 3 to 18 years of age using Lunar Prodigy absorptiometry

Nonunion and delayed union in lateral open wedge distal femoral osteotomies-a legitimate concern?

Due to a supposed high rate of nonunions in lateral open wedge distal femur osteotomy (LOWDFO), the medial closing wedge technique has been favoured for a long time. The aim of this study was to report the occurrence of delayed- and nonunions following LOWDFO. We hypothesized that the occurrence of nonunions needing revision surgery is comparable to medial closing osteotomies. Forty-one patients were treated with LOWDFO with a minimum follow-up of 12months. Parameters such as age, gender, body mass index, valgus angle, the heights of the opening wedge, as well as the type of osteotomy (biplane vs single plane) were collected. Delayed union and nonunion were evaluated on radiographs along with clinical symptoms. The study group consisted of 21 females and 20 males, with a median age of 37years at the time of surgery. Removal of hardware was performed in 63% after 1.3years (0.6-2.1years). The median preoperative valgus angle was 6.1° valgus (range 2-15.5°). The heights of the opening wedge ranged from 2 to 12mm (mean 5.3mm). Hinge fracture of the medial cortex was seen in 39%. Three patients had a delayed union, and one patient had a nonunion requiring revision surgery. LOWDFO is a safe alternative to MCWDFO. Although radiolucency of the osteotomy gap can be evident on radiographs even after 12months, this does not reflect the clinical finding. The nonunion rate is proven to be low and comparable with the nonunion rates of MCWDFOs as well as open wedge HTOs.

The Role of the Lateral Soft Tissues in Controlling Anterior Translation And Internal Rotation of the Tibia, and An Investigation of Lateral Reconstructions Accompanying ACL Reconstruction

Introduction:There is considerable current interest in the role of the lateral soft tissue structures in the context of ACL deficiency (ACLD). Of course the topic is not new but a re-visitation, although with improved experimental techniques available. It was clear that there was a rush to create surgical techniques based on the ‘Anterolateral Ligament’ (ALL) but without investigative ‘due-diligence’ and without consideration that other structures may be important, or more important.Objectives:To study the anatomy and biomechanics of the lateral soft tissues relevant to the ACL and ACL reconstruction techniques investigating isometricity, structures’ contributions to resistance of anterior tibial translation (ATT), internal rotation (IR), and pivot shift (PS). Also we studied the impact of various reconstructions on restoration of kinematics and potential over-constraint and effects on articular surface compression load.Methods:Several studies were undertaken. In all healthy fresh-frozen cadaveric specimens were used. Descriptive anatomy was described. Length changes of suture fixed at structure and reconstruction attachment points on the tibia and femur were measured with linear variable displacement transducers (LVDTs). To investigate structures’ contribution to resist translation and torque a 6-degrees of freedom robot with a universal force-moment sensor was used in a classic ‘cutting study’. The robot replayed the same movement with sequential sectioning of structures recording the decrease in force / torque needed to reach the same movement limit. In this way the structure’s resistance to motion as a percentage of the total could be calculated. In other studies knees were mounted in a test rig where knee kinematics were recorded from 0° to 100° of flexion by use of an optical tracking system. Joint surface compression was measured with Tekscan pressure-sensitive film.Results:The Anterolateral Ligament exists attaching to the tibia mid-way between the LCL attachment to the fibula and Gerdy’s tubercle, and the femur proximal and posterior to the femoral LCL attachment1. However the most isometric structure is the ITB2 from Gerdy’s tubercle to its attachments to the distal lateral femur. The ACL is the primary restraint to resist ATT, but is only the primary restraint to IR / PS close to extension. The ITB, with its attachments to the lateral distal femur, is the most important restraint at all other angles, whilst the ALL / capsule contribute very little restraint to ATT / IR / PS at any angle3. ITB-based tenodeses taken deep to the LCL, irrespective of femoral attachment points, are more isometric1 and restore kinematics more closely to normal compared to an ALL reconstruction. Fixation of the tenodeses with the knee with 0° tibial rotation, and tension of 20 N resulted in no change in tibio-femoral / patello-femoral contact pressures. Fixation with significant external rotation or excess tension (40 N) did increase contact pressures and lead to over-constraint.Conclusion:Despite recent interest the ALL is not as important to the ITB with its femoral attachments in controlling IR / PS. ITB-based tenodeses taken deep to the LCL perform well unless over-tensioned or fixed with tibial ER in the lab. The Anterolateral Ligament: Anatomy, length changes and association with the Segond fracture A. L. Dodds, C. Halewood, C. M. Gupte, A. Williams, and A. A. Amis. Bone Joint J 2014 96-B: 325-331 Length change patterns of the lateral extra-articular structures of the knee and related reconstructions. C.Kittl, C Halewood, J Stephen, Gupte C, A Weiler, A. Williams, A.A. Amis. AJSM 2015; 43(2): 354-62 The role of the anterolateral structures and the ACL in controlling laxity of the intact and ACL-deficient knee. C Kittl, H El-Daou, KK Athwal, CM Gupte, A Weiler, A Williams, AA Amis. AJSM 2016; 44: 345-354

The Role of the Lateral Soft Tissues in Controlling Anterior Translation And Internal Rotation of the Tibia, And An Investigation of Lateral Reconstructions Accompanying ACL Reconstruction

Introduction:There is considerable current interest in the role of the lateral soft tissue structures in the context of ACL deficiency (ACLD). Of course the topic is not new but a re-visitation, although with improved experimental techniques available. It was clear that there was a rush to create surgical techniques based on the ‘Anterolateral Ligament’ (ALL) but without investigative ‘due-diligence’ and without consideration that other structures may be important, or more important.Objectives:To study the anatomy and biomechanics of the lateral soft tissues relevant to the ACL and ACL reconstruction techniques investigating isometricity, structures’ contributions to resistance of anterior tibial translation (ATT), internal rotation (IR), and pivot shift (PS). Also we studied the impact of various reconstructions on restoration of kinematics and potential over-constraint and effects on articular surface compression load.Methods:Several studies were undertaken. In all healthy fresh-frozen cadaveric specimens were used. Descriptive anatomy was described. Length changes of suture fixed at structure and reconstruction attachment points on the tibia and femur were measured with linear variable displacement transducers (LVDTs). To investigate structures’ contribution to resist translation and torque a 6-degrees of freedom robot with a universal force-moment sensor was used in a classic ‘cutting study’. The robot replayed the same movement with sequential sectioning of structures recording the decrease in force / torque needed to reach the same movement limit. In this way the structure’s resistance to motion as a percentage of the total could be calculated. In other studies knees were mounted in a test rig where knee kinematics were recorded from 0° to 100° of flexion by use of an optical tracking system. Joint surface compression was measured with Tekscan pressure-sensitive film.Results:The Anterolateral Ligament exists attaching to the tibia mid-way between the LCL attachment to the fibula and Gerdy’s tubercle, and the femur proximal and posterior to the femoral LCL attachment1. However the most isometric structure is the ITB2 from Gerdy’s tubercle to its attachments to the distal lateral femur. The ACL is the primary restraint to resist ATT, but is only the primary restraint to IR / PS close to extension. The ITB, with its attachments to the lateral distal femur, is the most important restraint at all other angles, whilst the ALL / capsule contribute very little restraint to ATT / IR / PS at any angle3. ITB-based tenodeses taken deep to the LCL, irrespective of femoral attachment points, are more isometric1 and restore kinematics more closely to normal compared to an ALL reconstruction. Fixation of the tenodeses with the knee with 0° tibial rotation, and tension of 20 N resulted in no change in tibio-femoral / patello-femoral contact pressures. Fixation with significant external rotation or excess tension (40 N) did increase contact pressures and lead to over-constraint.Conclusion:Despite recent interest the ALL is not as important to the ITB with its femoral attachments in controlling IR / PS. ITB-based tenodeses taken deep to the LCL perform well unless over-tensioned or fixed with tibial ER in the lab. 1 The Anterolateral Ligament: Anatomy, length changes and association with the Segond fracture A. L. Dodds, C. Halewood, C. M. Gupte, A. Williams, and A. A. Amis. Bone Joint J 2014 96-B: 325-331 2 Length change patterns of the lateral extra-articular structures of the knee and related reconstructions.C.Kittl, C Halewood, J Stephen, Gupte C, A Weiler, A. Williams, A.A. Amis. AJSM 2015; 43(2): 354-62 3 The role of the anterolateral structures and the ACL in controlling laxity of the intact and ACL-deficient knee. C Kittl, H El-Daou, KK Athwal, CM Gupte, A Weiler, A Williams, AA Amis. AJSM 2016; 44: 345-354

Anterolateral Ligament of the Knee: Anatomy, Function, Imaging, and Treatment

The anterolateral ligament (ALL) of the knee has gained attention recently for its potential role in rotational stability of the knee, especially in association with anterior cruciate ligament (ACL) injuries. Anatomic studies have characterized the ALL as it runs in an anteroinferior and oblique direction from the lateral distal femur to the anterolateral proximal tibia, although the prevalence and variance of this ligament are not well understood. Magnetic resonance imaging and ultrasound have identified the ligament and linked it with the classically described Segond fracture. While the ALL likely plays a role in rotational stability of the knee, further studies investigating the significance of ALL injuries and the role of ALL reconstruction in combination with ACL reconstruction are warranted.

Low bone mineral density and fractures are highly prevalent in pediatric patients with spinal muscular atrophy regardless of disease severity

Patients with Spinal Muscular Atrophy (SMA) are at risk for poor bone health. The prevalence of fractures, low areal bone mineral density (aBMD; Z-score ≤−2.0) of the lateral distal femur and of osteoporosis by SMA subtype is not known. We aimed to describe the natural history of bone health in patients with SMA prior to bisphosphonate treatment. We reviewed data from 85 eligible patients with SMA ages 12 months to 18 years, seen at a single institution between January 2005 and July 2016. Fracture history was reported at annual clinic visits. aBMD was obtained from dual energy x-ray absorptiometry scans of the lumbar spine, total body, and lateral distal femur. 85% of patients had aBMD Z-scores ≤−2.0 SD and were progressively lower with worsening SMA severity. Longitudinal aBMD Z-scores of the lateral distal femur decreased with age. Fractures occurred in 38% (32/85) of patients with the femur being the most common location (25 of 57 fractures). Thirteen percent of patients fulfilled criteria for osteoporosis. Low aBMD and femur fractures are highly prevalent in all SMA subtypes from a young age; however, few patients met the criteria for osteoporosis. Poor bone health may be an under-recognized comorbidity of SMA.

Bone health measures in glucocorticoid-treated ambulatory boys with Duchenne muscular dystrophy

Osteoporosis is a major problem in boys with Duchenne Muscular Dystrophy (DMD), attributable to muscle weakness and glucocorticoid therapy. Consensus regarding bone health assessment and management is lacking. Lumbar spine areal bone mineral density (defined as bone mass per area of bone) by dual-energy X-ray absorptiometry (DXA) is frequently the primary measure used, but has limitations for boys with DMD. We retrospectively studied 292 ambulant glucocorticoid-treated boys with DMD categorized by functional mobility score, FMS 1, 2 or 3. We assessed DXA whole body and lumbar spine areal bone mineral density and content Z-scores adjusted for age and height, lateral distal femur areal bone mineral density Z-scores, frequency of fractures, and osteoporosis by International Society for Clinical Densitometry 2013 criteria. Whole body and femoral DXA indices decreased, while spine fractures increased, with declining motor function. Lumbar spine areal bone mineral density Z-scores appeared to improve with declining motor function. Bone mineral content Z-scores were consistently lower than corresponding bone mineral density Z-scores. Our findings highlight the complexity of assessing bone health in boys with DMD. Bone health indices worsened with declining motor function in ambulant boys, but interpretation was affected by measure and skeletal site examined. Whole body bone mineral content may be a valuable measure in boys with DMD. Lumbar spine areal bone mineral density Z-score as an isolated measure could be misleading. Comprehensive management of osteoporosis in boys with DMD should include vertebral fracture assessment.

Bone mineral density in mucopolysaccharidosis IVB

To date, the only published reports of bone mineral density (BMD) in MPS IV involve patients with MPS IVA; no reports exist describing BMD for MPS IVB. In this prospective study of BMD in three patients with MPS IVB, BMD was acquired by dual-energy X-ray absorptiometry (DXA) at whole body (WB), lumbar spine (LS), and lateral distal femur (LDF). Functional abilities, ambulatory status, medical history, and height z-score were evaluated. Three patients with MPS IVB (two females), aged 17.7, 31.4 and 31.7years, were evaluated. Every patient was ambulatory and one sustained two fractures caused by trauma. Whole body and hip DXA scans were technically invalid in every patient due to the presence of prosthetic hip hardware. Lumbar spine was valid in only 1 patient due skeletal abnormalities, and was normal (Z-score of −0.8). The LDF was valid in every patient and was low at all three regions of interest: average LDF z-scores were −3.1 (range, −2.9 to −3.6), −2.3 (range, −2.0 to −2.5), and −2.1 (range, −2.0 to −2.3) for region 1–region 3, respectively. Patients with MPS IVB have low BMD of the lower extremities even with full-time ambulation. Routine body sites to measure by DXA were problematic; hip and WB were invalid due to artifact, and LS had limited utility. The LDF was the only body site consistently available on all patients. Patients did not experience low-energy fractures despite low BMD.

Bone mineral density in MPS IV A (Morquio syndrome type A).

Mucopolysaccharidosis IV A (MPS IV A), Morquio A, is caused by deficiency in lysosomal enzyme N-acetylgalactosamine-6-sulfate sulfatase (GALNS), which is responsible for the catabolism of the glycosaminoglycans (GAGs) keratan sulfate (KS) and chondroitin 6-sulfate (C6S). Accumulation of GAGs results in disrupted cartilage formation and skeletal dysplasia. In this prospective cross-sectional study, bone mineral density (BMD) of the whole body (WB), lumbar spine (LS), and lateral distal femur (LDF) was acquired by dual-energy X-ray absorptiometry (DXA) on patients with MPS IV A. Functional abilities, medical history, Tanner score, and laboratory results were reviewed. Age and sex-matched norms were used to calculate Z-scores. Participants included 18 patients (13 females; 16 were unrelated) with a mean age of 21.4years (3.3 to 40.8years). While every patient was able to bear weight, 9 were full-time ambulators. Whole-body DXA could be obtained on only 6 patients (5 full-time ambulators) because of respiratory compromise caused by the position, presence of hardware, or positioning difficulties. Mean WB Z-score was -2.0 (range-0.3 to -4.1). Technical issues invalidating LS DXA in 8 patients included kyphosis at the thoracolumbar junction resulting in overlap of vertebrae in the posterior-anterior view. Mean LS BMD Z-score in full-time ambulators was -3.4 (range-1.6 to -5.0) and in the non-/partial ambulator was -4.0 (-3.7 to -4.2). Lateral distal femur BMD was acquired on every patient, and average Z-scores were -2 or less at all sites; full-time ambulators exhibited higher BMD. In conclusion, the LDF proved to be the most feasible site to measure in patients with MPS IV A. The higher LDF values in ambulators suggest this should be a consideration in promoting bone health for this group.

Lateral Femoral Condyle Flap: An Alternative Source of Vascularized Bone From the Distal Femur

To elucidate the vascular anatomy of the superolateral geniculate artery (SLGA) and its supply to the periosteum of the lateral femoral condyle (LFC) and to provide guidelines for flap design and describe an illustrative case. Thirty-one fresh cadaveric limbs were dissected. The vascular anatomy of the SLGA and its distal branches to skin, muscle, and periosteum were identified. Fluoroscopic images were taken during continuous perfusion of a radiopaque contrast dye into the SLGA. Intra-arterial injections of latex rubber were performed in 12 cadaver limbs. The vascular territory was traced from the SLGA to its distal branches, and surrounding soft tissues were dissected. The SLGA originated from the popliteal artery 4.9 ± 1.2 cm (range, 2.8-7 cm) from the knee joint and its pedicle diameter was 1.8 ± 0.5 mm (range, 1-3 mm). SGLA pedicle-specific fluoroscopic angiography demonstrated a dense filigree of vessels over the lateral distal femur. Arterial latex injections confirmed that the SLGA supplied the periosteum of the LFC and distal femur shaft. The proximal-most extent of periosteal perfusion was 11.7 ± 2.1 cm (range, 9.3-14.1 cm) from the knee joint. The average pedicle length of LFC osteoperiosteal flaps was 4.8 ± 0.9 cm (range, 3.5-6.3 cm). The LFC flap consistently demonstrated almost 12 cm of femur length perfusion based on the SLGA pedicle. The anatomy of this flap enables chimeric designs combining soft tissue, bone, and cartilage. The vascularized LFC flap is an option for reconstruction of osseous defects of the upper extremity.