Osteotomy Site Venting Enhances Femoral Bone Consolidation With Magnetic Intramedullary Lengthening Nails.

BACKGROUND: Magnetic intramedullary lengthening nailing has demonstrated benefits over external fixation devices for femoral bone lengthening. These include avoiding uncomfortable external fixation and associated pin site infections, scarring, and inhibition of muscle or joint function. Despite this, little has changed in the field of biologically enhanced bone regeneration. Venting the femoral intramedullary canal at the osteotomy site before reaming creates egress for bone marrow during reaming. The reamings that are extruded from vent holes may function as a prepositioned bone graft at the distraction gap. The relationship between venting and the consolidation of regenerating bone remains unclear. QUESTIONS/PURPOSES: (1) Do bone marrow reamings extruded through venting holes enhance the quality of bone regeneration and improve healing indices and consolidation times? (2) Is venting associated with a higher proportion of complications than nonventing? METHODS: We performed a retrospective study of femoral lengthening performed at one hospital from December 2012 to February 2022 using a magnetic intramedullary lengthening nail with or without venting at the osteotomy site before reaming. This was a generally sequential series, in which the study groups were assembled as follows: Venting was performed between July 2012 and August 2016 and again from November 2021 onward. Nonventing was used between October 2016 and October 2021 because the senior author opted to create drill holes after the reaming procedure to avoid commitment to the osteotomy level before completing the reaming procedure. Outcomes were evaluated based on bone healing time, time to achieve full weightbearing, and complications. Sixty-one femoral lengthening procedures were studied (in 33 male and 28 female patients); two patients were excluded because of implant breakage. The mean age was 17 ± 5 years. The mean amount of lengthening was 55 ± 13 mm in the venting group and 48 ± 16 mm in the nonventing group (mean difference 7 ± 21 [95% CI 2 to 12]; p = 0.07). The healing index was defined as the time (in days) required for three cortices to bridge with new bone formation divided by the length (in cm) lengthened during the clinical protocol. This index signifies the bone formation rate achieved under the specific conditions of the protocol. Full weightbearing was allowed upon bridging the regenerated gap on three sides. Consolidation time was defined as the total number of days from the completion of the lengthening phase until adequate bone union (all three cortices healed) was achieved and full weightbearing was permitted. This time frame represents the entire healing process after the lengthening is complete divided by the amount of lengthening achieved (in cm). Patient follow-up was conducted meticulously at our institution, and we adhered to a precise schedule, occurring every 2 weeks during the distraction phase and every 4 weeks during the consolidation phase. There were no instances of loss to follow-up. Every patient completed the treatment successfully, reaching the specified milestones of weightbearing and achieving three cortexes of bone bridging. RESULTS: The mean healing index time in the venting group was faster than that in the nonventing group (21 ± 6 days/cm versus 31 ± 22 days/cm, mean difference 10 ± 23 [95% CI 4 to 16]; p = 0.02). The mean consolidation time was faster in the venting group than the nonventing group (10 ± 6 days/cm versus 20 ± 22 days/cm; mean difference 10 ± 23 [95% CI 4 to 15]; p = 0.02). No medical complications such as deep vein thrombosis or fat or pulmonary embolism were seen. Two patients had lengthy delays in regenerate union, both of whom were in the nonventing group (healing indexes were 74 and 62 days/cm; consolidation time was 52 and 40 days/cm). CONCLUSION: Femoral lengthening with a magnetic intramedullary lengthening nail healed more quickly with prereaming venting than with nonventing, and it allowed earlier full weightbearing without any major associated complications. Future studies should evaluate whether there is a correlation between the number of venting holes and improvement in the healing index and consolidation time. LEVEL OF EVIDENCE: Level III, therapeutic study.

Analysis of the Actions of RARγ Agonists on Growing Osteochondromas in a Mouse Model.

The actions of the retinoic acid nuclear receptor gamma (RARγ) agonist, palovarotene, on pre-existing osteochondromas were investigated using a mouse multiple osteochondroma model. This approach was based on the knowledge that patients often present to the clinic after realizing the existence of osteochondroma masses, and the findings from preclinical investigations are the effects of drugs on the initial formation of osteochondromas. Systemic administration of palovarotene, with increased doses (from 1.76 to 4.0 mg/kg) over time, fully inhibited tumor growth, keeping the tumor size (0.31 ± 0.049 mm3) similar to the initial size (0.27 ± 0.031 mm3, p = 0.66) while the control group tumor grew (1.03 ± 0.23 mm3, p = 0.023 to the drug-treated group). Nanoparticle (NP)-based local delivery of the RARγ agonist also inhibited the growth of osteochondromas at an early stage (Control: 0.52 ± 0.11 mm3; NP: 0.26 ± 0.10, p = 0.008). Transcriptome analysis revealed that the osteoarthritis pathway was activated in cultured chondrocytes treated with palovarotene (Z-score = 2.29), with the upregulation of matrix catabolic genes and the downregulation of matrix anabolic genes, consistent with the histology of palovarotene-treated osteochondromas. A reporter assay performed in cultured chondrocytes demonstrated that the Stat3 pathway, but not the Stat1/2 pathway, was stimulated by RARγ agonists. The activation of Stat3 by palovarotene was confirmed using immunoblotting and immunohistochemistry. These findings suggest that palovarotene treatment is effective against pre-existing osteochondromas and that the Stat3 pathway is involved in the antitumor actions of palovarotene.

Congenital Synostosis of the Knee: Long-term Outcomes of Limb Reconstruction Surgery.

BACKGROUND: Congenital synostosis of the knee is a rare condition with limited data on treatment options and outcomes. This study reports clinical findings, treatment approach, and surgical/clinical outcomes for congenital synostosis of the knee. METHODS: An institutional review board-approved retrospective review of patients with congenital synostosis of the knee presenting to 2 institutions between 1997 and 2021 was performed. RESULTS: Eight patients (13 knees) with a median follow-up of 11.3 years (3.3 to 17 y) were included. Seven patients had associated syndromes. Patients presented with an average knee flexion deformity of 100° (range 60 to 130°) and delayed walking ability. Seven patients had associated upper extremity hypoplasia/phocomelia. The average age at the index surgery was 4.3 years (range 1.2 to 9.2 y). Synostosis resection with gradual deformity correction was performed in most patients. An attempt was made at a mobile knee in some patients, but all went on to knee fusion. Mean flexion deformity at final follow-up was 11.6° (range: 0 to 40°) and 5 limbs were fused in full extension. Mean limb length discrepancy at final follow-up was 6.8 cm (range: 0 to 8 cm). All patients maintained their improved ambulation status at final follow-up. Twenty-two complications were identified. CONCLUSIONS: Reliable correction of the deformity associated with congenital knee synostosis was achieved at a median follow-up of 11 years. Importantly, all patients maintained their improved ambulation at final follow-up. This is the largest study on patients with congenital knee synostosis and outlines a reconstructive approach to improve ambulatory status. LEVEL OF EVIDENCE: Level IV.

Plate-assisted bone-segment transport in the femur with 2 internal lengthening nails: a technical note and a case report.

A novel technique to resolve large bone defects, using 2 internal lengthening nails (ILNs), one antegrade and one retro-grade, aligned in a custom-made tube is presented. A 28-year-old, healthy, asymptomatic male presented with a slowly growing mass in the left femur.

Does An Osteotomy Performed in Congenital Pseudarthrosis of the Tibia Heal?

BACKGROUND: Shortening and deformity of the tibia commonly occur during the treatment of congenital pseudarthrosis of the tibia (CPT). The role of osteotomies in lengthening and deformity correction remains controversial in CPT. This study evaluates the approach to and outcome after osteotomy performed in CPT. METHODS: We performed an IRB approved retrospective review of consecutive patients with CPT treated at our institution from 2010 through 2019. Patients who underwent osteotomies were included in this study. RESULTS: Nine patients (10 osteotomies-5 proximal metaphyseal and 5 diaphyseal) with a median age at osteotomy of 8.9 years (range: 4 to 21 y) were included. Six patients had neurofibromatosis-1, 1 had cleidocranial dysplasia, and 2 patients had idiopathic CPT. Four osteotomies were performed for deformity correction, 3 osteotomies to allow intramedullary instrumentation, and 3 osteotomies for lengthening. Five osteotomies were preceded by zolendronate treatment before surgery. Nine were fixed with a rod supplemented with external fixation (7) or locking plates (2). One osteotomy was stabilized with locked intramedullary nailing alone. Four osteotomies were supplemented with autologous bone graft, and bone morphogenic protein-2 was utilized in 3 osteotomies. Median time to healing was 222.5 days (range: 124 to 323 d). One osteotomy (locked intramedullary nailing) required grafting at 5.5 months and then healed uneventfully. Median healing index for patients undergoing lengthening was 57.9 days/cm (range: 35 to 81 d/cm). All 3 osteotomies performed for lengthening required a second osteotomy for preconsolidation at a mean of 34 days. Other complications included compartment syndrome requiring fasciotomy (n=2), tibial osteomyelitis (n=1), and fracture distal to cross-union (n=1). CONCLUSIONS: Contrary to much of the established practice, osteotomies may be safely performed in CPT for various indications. All osteotomies healed with only 1 osteotomy requiring secondary bone grafting. Although time to healing of the osteotomy was generally prolonged, this study suggests, somewhat surprisingly, that preconsolidation can occur frequently in lengthening procedures. LEVEL OF EVIDENCE: Level IV-case series.

Foot Deformity Correction Planning in the Sagittal Plane Based on the Vitruvian Foot First Metatarsal Mechanical Axis and Calcaneus Anatomic Axis.

The aim of the study was to test a novel planning method for simultaneous midfoot and hindfoot deformity correction, based on reference lines and angles (RLA) of the talus, calcaneus and first metatarsal in 64 normal radiographs from 55 patients. Talus Joint Line (TJL), from the border of the articular surface of the talus and the posterior process of talus, and mechanical axis of the first metatarsal form the mechanical Lateral Talometatarsal Angle (mLTMA) = 23.6º (±3.2). The length of the first metatarsal line was measured from its intersections with the TJL and first metatarsal head and it was 4.3 (±0.94) times longer that TJL (k). For hindfoot correction planning, we used an axis of the calcaneus formed by a line starting at the middle of the back of the calcaneal tuberosity and going perpendicular to a line from the top point to the bottom point of the calcaneal tuberosity. The intersection of the calcaneal line and the anterior continuation of TJL form the lateral heel angle (LHA) = 15.2º (±3.4).The following parameters were identified: the length from the intersection point of the lines and anterior point of TJL was 2.56 ± 1.1 longer than TJL (k1). The length from the intersection point and posterior border of the calcaneus was 4.59 ± 1.0 times longer than TJL (k2). Planning using the new method was demonstrated and confirmed on 3 case examples. A novel method for analysis and planning of midfoot and hindfoot sagittal plane deformity correction may be used separately or simultaneously for complex deformity correction.

Amputation Versus Limb Reconstruction for Fibula Hemimelia: A Meta-analysis.

PURPOSE: Fibula hemimelia is the most common congenital deficiency of long bones. Primary treatment options include amputation with prosthetic fitting or limb reconstruction. The aim of our study was to conduct a systematic review comparing amputation with limb reconstruction for fibula hemimelia. METHODS: MEDLINE, EMBASE, Web of Science, Elsevier Scopus, and the Cochrane Registry of Clinical Trials were searched from 1951 to 2019 for studies that evaluated amputation versus limb reconstruction for fibula hemimelia. Random effect models were utilized for the meta-analytic comparisons of amputation versus limb reconstruction for patient satisfaction and surgical complications. Descriptive, quantitative, and qualitative data were extracted. RESULTS: Seven retrospective cohort studies were eligible for the meta-analysis, with a total of 169 fibula hemimelia cases. Amputation resulted in an odds ratio of 6.8 (95% confidence interval: 2.4, 19.2) when compared with limb reconstruction in terms of patient satisfaction. Furthermore, limb reconstruction was found to have an odds ratio of 28 (95% confidence interval: 7.8, 100.3) for complications. The total surgical complication rates in the amputation and limb reconstruction groups were 0.2 and 1.2 complications per limb. The rate of surgical procedures per patient was 1.5 and 4.2 for amputation and limb reconstruction, respectively. CONCLUSIONS: The cumulative evidence at present indicates better patient satisfaction with less surgical complications and less number of procedures with amputation for fibula hemimelia when compared with limb reconstruction. Absence of uniform protocols make it difficult to compare results accurately. LEVEL OF EVIDENCE: Level III-therapeutic.

Latest Advances in Limb Lengthening Using Magnetically Controlled Intramedullary Lengthening Nails.

Magnetically controlled intramedullary lengthening nails (MCILN) have revolutionized the field of limb lengthening and deformity correction. They allow for accurate and precise distraction with excellent patient outcomes and satisfaction. Though potentially technically easier than external fixation, general deformity principles and bone and soft-tissue biology must be considered for successful use. MCILN can address deformities of a wide range of etiologies including congenital, posttraumatic, post-infectious, tumor, and many others with excellent healing rates and outcomes as well as better patient satisfaction and similar cost compared to external fixation. Of the approximately 10,000 MCILN that have been implanted (written communication, NuVasive, Inc., San Diego, California), about 749 cases have been reported in the published literature. Applications outside of deformity correction are on the rise, with new uses reported in reconstruction after tumor resection and acute trauma. This review of MCILN summarizes the history, recent advances, and results of MCILN treatment in a multitude of clinical applications.

Understanding the Action of RARγ Agonists on Human Osteochondroma Explants.

Osteochondromas are cartilage-capped growths located proximate to the physis that can cause skeletal deformities, pain, limited motion, and neurovascular impingement. Previous studies have demonstrated retinoic acid receptor gamma (RARγ) agonists to inhibit ectopic endochondral ossification, therefore we hypothesize that RARγ agonists can target on established osteochondromas. The purpose of this study was to examine the action of RARγ agonist in human osteochondromas. Osteochondroma specimens were obtained during surgery, subjected to explant culture and were treated with RARγ agonists or vehicles. Gene expression analysis confirmed the up-regulation of RARγ target genes in the explants treated with NRX 204647 and Palovarotene and revealed strong inhibition of cartilage matrix and increased extracellular matrix proteases gene expression. In addition, immunohistochemical staining for the neoepitope of protease-cleaved aggrecan indicated that RARγ agonist treatment stimulated cartilage matrix degradation. Interestingly, cell survival studies demonstrated that RARγ agonist treatment stimulated cell death. Moreover, RNA sequencing analysis indicates changes in multiple molecular pathways due to RARγ agonists treatment, showing similarly to human growth plate chondrocytes. Together, these findings suggest that RARγ agonist may exert anti-tumor function on osteochondromas by inhibiting matrix synthesis, promoting cartilage matrix degradation and stimulating cell death.

Foot Deformity Correction Planning in the Sagittal Plane Based on the Vitruvian Foot First Metatarsal Anatomic Axis.

The aim of this study was to test a novel planning method for midfoot deformity correction, based on reference lines and angles (RLA) of talus and first metatarsal of 64 normal radiographs from 55 patients. The anatomic lateral talometatarsal angle (aLTMA), resulting from the intersection of talus joint line (TJL), from the border of the articular surface of the talus to the posterior process of talus, and the anatomic axis of the first metatarsal, was 28.5° ± 4.5°. The intersection of those 2 lines divided the TJL in 2 segments (ac and ab) with the ratio k1 = 0.7 ± 0.3. The length of the first metatarsal line was measured from its intersection with the TJL and first metatarsal head, and it was 3.6 times longer that of the TJL (k2). To analyze foot deformity, we propose to draw the TJL line as follows. Use the k1 ratio to determine the point where the aLMTA intersects the TJL. From this point, an idealized anatomic first metatarsal line should be drawn, at 28.5° from the TJL. The distal end of that line is based on the k2 ratio (3.6 × TJL length). Next, the actual anatomic lateral talometatarsal line of the deformed foot is drawn. The intersection between these 2 lines identifies the apex and magnitude of the deformity. Deformity correction planning using the proposed method was demonstrated and confirmed in 2 cases. A reference method for analysis and planning of midfoot sagittal plane deformity correction independent of foot position relative to the ankle joint or the presence of concomitant hindfoot deformity appears promising for future investigation and use.

The Natural History of Lower Extremity Malalignment.

BACKGROUND: Lower extremity malalignment is a common problem presented to pediatric orthopaedists. Risk for early arthritis is often a concern among parents seeking advice and treatment. We seek to review previous research with regard to the natural history of malalignment. METHODS: A search of available literature on PubMed was constructed to capture articles covering the natural history of malalignment, secondary to childhood fracture as well as congenital and acquired pediatric deformity. In order to remain strictly relevant to pediatrics, articles reviewing deformities acquired in adulthood were not referenced. Biomechanical data and animal studies were included when deemed appropriate. RESULTS: High-quality data with regard to long-term risk of arthritis due to malalignment is lacking. Through a combination of biomechanical data, animal models, and a small body of longitudinal clinical data, it is clear that some patients with malalignment progress to early arthritic change. Unfortunately, detailed risk factors of who is at high risk versus low risk remains difficult to determine. CONCLUSIONS: Treatment of minor lower extremity malalignment is not supported by the current orthopaedic literature. Treatment plans should focus on the presence of symptoms, and in asymptomatic but severe cases. Even in more severe cases, strong evidence to support prophylactic realignment is not available. Evidence to suggest that preventative realignment is superior to intervention at the time of symptom onset does not exist.

Lengthening With Monolateral External Fixation Versus Magnetically Motorized Intramedullary Nail in Congenital Femoral Deficiency.

BACKGROUND: Limb lengthening for congenital femoral deficiency (CFD) with or without fibular hemimelia can be performed with both external and internal devices. The purpose of this study is to compare clinical outcomes of femoral lengthening utilizing monolateral external fixation versus a magnetically motorized intramedullary nail in patients with CFD with or without fibular hemimelia. METHODS: This retrospective review included 62 patients with femoral lengthening, 32 patients had monolateral external fixation (group A), 30 patients had internal lengthening nail (group B). Mean age in years was 9.4±3.8 and 15.4±4.9 for groups A and B, respectively. Mean follow-up in years was 4.47±2.7 and 1.86±0.7 years for groups A and B, respectively. RESULTS: Mean lengthening achieved was 5.6±1.7 and 4.8±1.4 cm for group A and group B, respectively (P=0.052). Mean distraction index was 0.7±0.2 mm/d for group A and 0.7±0.2 mm/d for the group B (P=0.99). Mean consolidation index for group A was 29.3±12.7 and 34.8±11.2 d/cm for group B (P=0.08). Mean arc of motion before surgery and at final follow-up were similar between groups (P=0.35). Group A had significantly less range of motion at the end of distraction (P=0.0007) and at consolidation (P<0.0001). Both groups had similar rates of obstacles and complications. A significant difference between groups was found in the total problems (P<0.001) specifically with pin site/superficial infection (P<0.0001). CONCLUSIONS: The intramedullary nail had superior range of motion during the lengthening phase and at consolidation and an overall lower problem complication rate, while maintaining similar distraction and healing indices to monolateral external fixation. Internal lengthening nails represent a significant advance in technology for CFD lengthening. LEVEL OF EVIDENCE: Level IV-therapeutic.

How Accurate is the Multiplier Method in Predicting the Timing of Angular Correction After Hemiepiphysiodesis?

PURPOSE: The purpose of the study was to validate the accuracy of the Multiplier Method (MM) in predicting the timing of angular correction after hemiepiphysiodesis and to determine the role of using skeletal age when calculating those predictions. METHODS: This retrospective study included 131 physes in 77 patients treated with hemiepiphysiodesis to gradually correct a coronal plane deformity before skeletal maturity. To compare the MM's predictions to the actual treatment duration, the "desired angular correction" was considered the actual achieved angular correction determined from the "endpoint x-ray" (last x-ray before implant removal). We measured the bone length and width of the growth plate from the preoperative x-ray and calculated the MM's prediction of the duration of treatment based on the MM formula. We compared the predicted duration to the observed duration of treatment for each case. The difference was calculated by subtracting the observed duration from the predicted duration. The result was the "absolute difference," which is the number of months over or under predicted by the MM. RESULTS: The mean absolute difference between the MM's predicted duration and the observed duration was 2.31 months, which was highly significant (P≤0.001). The MM's prediction agreed with the observed duration of treatment (ie, zero absolute difference) in 15% of the predictions, 69% were under predicted, and 16% were over predicted. Sixty-eight percent of the absolute differences were within 3 months regardless of the direction of error. The mean difference was relatively less in genu varum cases and was statistically significant (P=0.047). Comparing the mean difference using chronological age and skeletal age in the formula showed no statistically significant difference. CONCLUSIONS: The MM has a tendency to under predict. Therefore, doing a guided growth right before skeletal maturity should be started 2 to 4 months earlier than suggested by the MM. Moreover, our data did not show that the bone age gave more accurate predictions than chronological age. LEVEL OF EVIDENCE: Level IV.

New Sagittal Plane Reference Parameters for Foot Deformity Correction Planning: The Vitruvian Foot.

Currently available methods for analysis and planning of post-traumatic or congenital deformity correction of the foot have some limitations. The aim of this retrospective study was to establish reference lines and angles (RLAs), and the resulting ratios, based on reproducible anatomic points on sagittal feet radiographs. The key starting point of our evaluation was the previously undescribed length and position of the talus joint line (TJL), from the border of the articular surface of the talus and the posterior process of talus. First, we calculated the relationships between the TJL and the axes of the foot, particularly the anatomic and mechanical lateral talometatarsal angle axes of the first metatarsal. Then, we assessed the relationships with the calcaneus, particularly the lateral heel angle. Finally, we calculated the parameters (angles and coefficients k) derived from the TJL and the foot-bearing points (foot quadrilateral). A total of 64 normal radiographs from 55 patients were analyzed. The values that resulted are as follows: anatomic lateral talometatarsal angle = 28.5° ± 4.5°, mechanical lateral talometatarsal angle = 23.6° ± 3.2°, lateral heel angle = 15.2° ± 3.4°, foot quadrilateral: abc = 144.6° ± 9.4°, bcd = 31.3° ± 2.6°, cda = 79.2° ± 9.8°, dab = 105.0° ± 8.3°, k1 = 3.09 ± 0.4, k2 = 3.77 ± 0.78, and k3 = 1.56 ± 0.24. Sagittal plane reference lines and angles are proposed, providing quantitative values for reference. These parameters have the potential to be easily implemented in foot deformity analysis and correction planning.

Ankle Range of Motion After Posterior Subtalar and Ankle Capsulotomy for Relapsed Equinus in Idiopathic Clubfoot.

INTRODUCTION: Posterior capsulotomy can correct residual clubfoot deformity, but has been associated with ankle stiffness. The purpose of this study was to evaluate clinical ankle range of motion (ROM) following posterior capsulotomy immediately postsurgery and during long-term follow-up. METHODS: A retrospective clinical and radiographic review of 257 patients (398 feet) was performed to evaluate all patients who required a posterior capsulotomy as part of their clubfoot management. Twenty feet (16 patients) were identified with a mean age of 73.3±37.7 months and mean Pirani score of 5.2±0.8 points. Following capsulotomy, a long-leg cast was placed and maintained for a mean of 26 days (range, 21 to 35 d). At cast removal, parents were trained and instructed to immediately begin home physiotherapy. The capsulotomy cohort was age and sex matched to a cohort treated exclusively with the Ponseti method for comparison. Children in the comparison cohort had a mean Pirani score of 5.7±0.8 points. RESULTS: The mean dorsiflexion in the capsulotomy cohort significantly increased comparing the preoperative to the immediate postoperative ROM (from -6.5 to +9.7 degrees). No significant reduction in this gain was observed at latest follow-up (to +8.3 degrees). No significant difference in the plantar-flexion angle was found. Radiographically, a significant improvement in the lateral anterior tibial-calcaneal angle angles was found (P<0.05). CONCLUSIONS: If utilizing our protocol for early mobilization, limited use of capsulotomy to treat relapsed clubfoot does not necessarily reduce ankle ROM. Our protocol of placing the feet in casts for a shorter duration of time and providing early physiotherapy helps maintain ankle ROM after a posterior capsulotomy. LEVEL OF EVIDENCE: Level III-therapeutic study.

Evaluation of a Mobile Application for Multiplier Method Growth and Epiphysiodesis Timing Predictions.

BACKGROUND: The multiplier method (MM) is frequently used to predict limb-length discrepancy and timing of epiphysiodesis. The traditional MM uses complex formulae and requires a calculator. A mobile application was developed in an attempt to simplify and streamline these calculations. We compared the accuracy and speed of using the traditional pencil and paper technique with that using the Multiplier App (MA). METHODS: After attending a training lecture and a hands-on workshop on the MM and MA, 30 resident surgeons were asked to apply the traditional MM and the MA at different weeks of their rotations. They were randomized as to the method they applied first. Subjects performed calculations for 5 clinical exercises that involved congenital and developmental limb-length discrepancies and timing of epiphysiodesis. The amount of time required to complete the exercises and the accuracy of the answers were evaluated for each subject. RESULTS: The test subjects answered 60% of the questions correctly using the traditional MM and 80% of the questions correctly using the MA (P=0.001). The average amount of time to complete the 5 exercises with the MM and MA was 22 and 8 minutes, respectively (P<0.0001). CONCLUSIONS: Several reports state that the traditional MM is quick and easy to use. Nevertheless, even in the most experienced hands, performing the calculations in clinical practice can be time-consuming. Errors may result from choosing the wrong formulae and from performing the calculations by hand. Our data show that the MA is simpler, more accurate, and faster than the traditional MM from a practical standpoint. LEVEL OF EVIDENCE: Level II.

Prophylactic Intramedullary Rodding Following Femoral Lengthening in Congenital Deficiency of the Femur.

INTRODUCTION: Femoral fracture after lengthening of congenital femoral deficiency (CFD) is a common complication with a high incidence, up to 50%. The purpose of this study is to determine whether prophylactic intramedullary Rush rodding after lengthening for CFD is an effective method to prevent femoral fracture and to assess any complications that may result. METHODS: Forty-five femoral lengthenings (43 CFD patients) were performed using external fixation. At the time of frame removal (except for 3 cases, 8 d later), prophylactic intramedullary Rush rods were inserted. Special reaming techniques were developed to pass a Rush rod through the solid regenerate bone and past sclerotic pin sites. Mean age at time of rodding was 6.9 years (range, 2.9 to 14.2 y). Mean duration of treatment with external fixation was 184 days (range, 146 to 461 d). Mean follow-up was 4.2 years (range, 1.3 to 8.2 y). This group of cases was compared with a historical cohort of 95 femoral lengthening procedures for CFD without prophylactic intramedullary rodding after frame removal previously performed at the same institute by the same surgeons. RESULTS: Eight cases (18%) developed fracture despite intramedullary rodding (1 case with relatively high-energy trauma, 3 cases during physical therapy, and 4 cases spontaneously). Only 4 of these fractures required intervention. Fractures were more common when a 3.18 mm Rush rod was used (28%) compared with 4.76 mm (8.3%). Patients with prophylactic rodding had a significantly lower incidence of femur fracture rodding than those who did not (18% vs. 34%, respectively; P=0.04). Three out of 45 Rush rods (7%) developed infection that were treated by debridement and removal of the rod, and all healed uneventfully without residual or recurrent infection. There were no cases of avascular necrosis. CONCLUSIONS: Prophylactic intramedullary rodding is a safe and effective method to prevent femoral fractures after CFD lengthening. Use of 4.76 mm rod is preferred. The risk of infection is acceptable, when compared with the risk of fracture, loss of length, and angulation. LEVEL OF EVIDENCE: Level III-a retrospective comparative study.

Trochanteric Entry for Femoral Lengthening Nails in Children: Is It Safe?

BACKGROUND: Antegrade intramedullary (IM) nailing for skeletally immature femur fractures can damage the capital femoral epiphysis blood supply, leading to avascular necrosis (AVN) of the femoral head. Reported AVN rates are 2% for piriformis entry and 1.4% for trochanteric entry. None of previous reports described IM lengthening nails for limb lengthening procedures. We have used self-lengthening telescopic nails with a proximal Herzog bend and standard trochanteric entry for femoral lengthening in children. The purpose of this study is to determine whether trochanteric entry IM lengthening nails can be used safely (no AVN or proximal femoral deformity) in the skeletally immature femur. METHODS: A retrospective review was performed between 2004 and 2014 to determine all skeletally immature patients younger than 18 years of age who had a reamed IM lengthening nail inserted through the greater trochanter, with at least 1-year follow-up. RESULTS: Thirty-one femurs were lengthened in 28 patients (17 males and 11 females). The etiology was congenital femoral deficiency (10), achondroplasia (6), post-traumatic (5), hemihypertrophy (3), Ollier disease (2), and miscellaneous (5). An attending surgeon was present for all procedures. Mean age at time of surgery was 12.9 years (range, 7 to 17 y). Mean follow-up was 3.5 years (range, 1.4 to 9 y). The average amount of lengthening was 5.4 cm (range, 3 to 6.7 cm). Twenty-four nails were 10.7 mm in diameter. Seven nails were 12.5 mm in diameter. Intramedullary skeletal kinetic distractor was used in 18 femurs and PRECICE in 13 femurs. Ten segments (7 intramedullary skeletal kinetic distractor; 3 PRECICE) experienced 13 complications. None of the patients developed AVN or proximal femoral deformity. CONCLUSIONS: IM lengthening nails inserted through the greater trochanter may be utilized in skeletally immature patients without increased risk of AVN of the femoral head or proximal femoral deformity. Larger trials would be helpful to confirm our hypothesis. We recommend careful surgical technique with liberal use of the image intensifier to avoid trauma to the femoral head blood supply. LEVEL OF EVIDENCE: Level IV-therapeutic.

Muscle strength and knee range of motion after femoral lengthening.

Background and purpose - Femoral lengthening may result in decrease in knee range of motion (ROM) and quadriceps and hamstring muscle weakness. We evaluated preoperative and postoperative knee ROM, hamstring muscle strength, and quadriceps muscle strength in a diverse group of patients undergoing femoral lengthening. We hypothesized that lengthening would not result in a significant change in knee ROM or muscle strength. Patients and methods - This prospective study of 48 patients (mean age 27 (9-60) years) compared ROM and muscle strength before and after femoral lengthening. Patient age, amount of lengthening, percent lengthening, level of osteotomy, fixation time, and method of lengthening were also evaluated regarding knee ROM and strength. The average length of follow-up was 2.9 (2.0-4.7) years. Results - Mean amount of lengthening was 5.2 (2.4-11.0) cm. The difference between preoperative and final knee flexion ROM was 2° for the overall group. Congenital shortening cases lost an average of 5% or 6° of terminal knee flexion, developmental cases lost an average of 3% or 4°, and posttraumatic cases regained all motion. The difference in quadriceps strength at 45° preoperatively and after lengthening was not statistically or clinically significant (2.7 Nm; p = 0.06). Age, amount of lengthening, percent lengthening, osteotomy level, fixation time, and lengthening method had no statistically significant influence on knee ROM or quadriceps strength at final follow-up. Interpretation - Most variables had no effect on ROM or strength, and higher age did not appear to be a limiting factor for femoral lengthening. Patients with congenital causes were most affected in terms of knee flexion.

Regenerate bone stimulation following limb lengthening: a meta-analysis.

BACKGROUND: Limb lengthening with external fixation is performed to treat patients with leg length discrepancy or short stature. Although the procedure has a high rate of success, one potential drawback from limb lengthening is the amount of time spent in the fixation device while regenerate bone consolidates. Although some studies have assessed different treatment modalities, there has not been a study that has systematically evaluated whether low intensity pulsed ultrasound (LIPUS) or pulsed electromagnetic fields (PEMF) have significant effects on regenerate bone growth. The purpose of this study was to evaluate these two non-pharmacological treatment options to stimulate regenerate bone, and to assess whether they affect the treatment time in limb lengthening. METHODS: Utilizing the electronic databases Medline, Embase and Ovid, we performed a literature search for studies describing the application of LIPUS or PEMF following limb lengthening. With the aid of a statistical software package, Forest-Plots were generated to compare the differences in bone healing index with and without the use of regenerate bone stimulation. RESULTS: A total of 7 studies assessed these two bone stimulation modalities in a cohort of 153 patients. Overall, the mean healing index was 11.7 days/cm faster when using bone stimulation that in the comparison cohorts (33.7 vs 45.4 day, standardized mean difference of 1.16; p = 0.003). CONCLUSION: Amongst the drawbacks from limb lengthening is the relatively high rate of non- and delayed-union. Several methods, both pharmacological and non-pharmacological, have been investigated for their potential to stimulate the growth of regenerate bone. After systematically evaluating the limited and heterogeneous current literature, we found that LIPUS and PEMF both decreased the time for bone healing (healing index in days/cm) of the newly formed regenerate bone in an adequately selected cohort of patients that underwent limb lengthening. However, a high number of complications should be noted, which could be attributed to the lengthening procedure or to the additional bone stimulation. PROSPERO REGISTRATION NUMBER: CRD42016039024.