An Innovative Plate Concept for Rotational Guided Growth: A Porcine Pilot Study.

Background Rotational deformities in children are currently treated with an osteotomy, acute de-rotation, and surgical fixation. Meanwhile, guided growth is now the gold standard in pediatric coronal deformity correction. This study aimed to evaluate the feasibility of a novel implant intended for rotational guided growth (RotOs Plate) in a large porcine animal model. Methodology A submuscular plate was inserted on the medial and lateral aspect of the distal femoral physis of the left femur in 6 pigs. Each plate was anchored with a screw in the metaphysis and epiphysis respectively. The plates were expected to rotate the femur externally. The right femur acted as a control in a paired design. The animals were housed for 12 weeks after surgery. MRI scanning of both femora was performed before euthanasia after 12 weeks. Rotation was determined as the difference in the femoral version on MRI between the operated and non-operated femur after 12 weeks. Results External rotation in all operated femurs was observed. The mean difference in the femoral version on MRI between operated and non-operated femurs was 12.5° (range 9°-16°). No significant changes in axial growth were detected. Conclusions This study shows encouraging results regarding rotational guided growth, which may replace current invasive surgical treatment options for malrotation in children. However, further studies addressing potential secondary deformities are paramount and should be carried out.

Correction of rotational deformities in long bones using guided growth: a scoping review.

Purpose: The objective of this scoping review was to describe the extent and type of evidence of using guided growth to correct rotational deformities of long bones in children. Methods: This scoping review was conducted in accordance with the JBI methodology for scoping reviews. All published and unpublished studies investigating surgical methods using guided growth to perform gradual rotation of long bones were included. Results: Fourteen studies were included: one review, three clinical studies, and ten preclinical studies. In the three clinical studies, three different surgical methods were used on 21 children. Some degree of rotation was achieved in all but two children. Adverse effects reported included limb length discrepancy (LLD), knee stiffness and rebound of rotation after removal of tethers. Of the ten preclinical studies, two were ex vivo and eight were in vivo. Rotation was achieved in all preclinical studies. Adverse effects reported included implant extrusions, LLD, articular deformities, joint stiffness and rebound of rotation after removal of tethers. Two of the studies reported on histological changes. Conclusions: All studies conclude that guided growth is a potential treatment for rotational deformities of long bones. There is great variation in animal models and surgical methods used and in reported adverse effects. More research is needed to shed light on the best surgical guided growth method, its effectiveness as well as the involved risks and complications. Based on current evidence the procedure is still to be considered experimental. Level of evidence: 4.

Radiographic reference values of the central knee anatomy in 8-16-year-old children.

BACKGROUND AND PURPOSE: For correction of leg-length discrepancy or angular deformity of the lower limb in skeletally immature patients temporary or permanent (hemi-)epiphysiodesis can be employed. These are reliable treatments with few complications. Recently, radiographic analysis of treatment-related alterations of the central knee anatomy gained interest among pediatric orthopedic surgeons. To date the comparison and adequate interpretation of potential changes of the central knee anatomy is limited due to the lack of defined standardized radiographic references. We aimed to establish new reference values of the central knee anatomy. PATIENTS AND METHODS: A retrospective analysis of calibrated longstanding anteroposterior radiographs of 254 skeletally immature patients with a chronological age ranging from 8 to 16 years was conducted. The following radiographic parameters were assessed: (1) femoral floor angle, (2) tibial roof angle, (3) width at femoral physis, and (4) femoral notch-intercondylar distance. RESULTS: All observed radiographic parameters were normally distributed with a mean age of 12.4 years (standard deviation [SD] 2, 95% confidence interval [CI] 12.2-12.6). Mean femoral floor angle was 142° (SD 6, CI 141.8-142.9), mean tibial roof angle was 144° (SD 5, CI 143.7-144.1), mean width at femoral physis was 73 mm (SD 6, CI 72.8-73.9), and mean femoral notch-intercondylar distance was 8 mm (SD 1, CI 7.5-7.7). The estimated intraclass correlation coefficient values were excellent for all measurements. CONCLUSION: This study provides new radiographic reference values of the central knee anatomy for children between 8 and 16 years and we suggest considering values within the range of 2 SD as the physiological range.

Controlled rotation of long bones by guided growth: A proof of concept study of a novel plate in cadavers.

Our novel plate design has been developed for controlled rotation of long bones by guided growth. The objective of this proof-of-concept study was to evaluate the precision of the rotation in the femur. Twelve cadaverous femora of six adults (right = 6, left = 6) underwent an osteotomy at the level of the physeal scar. The plates were inserted on each side of the distal femur. Growth was simulated by axial distraction of the bone segments. The femur was stabilized using a unilateral external fixator. Femoral torsion was assessed with computed tomography (CT) and with an electric goniometer before and after distraction. The obtained rotation was compared to the predicted rotation based on the dimension of the plate and the bone. All femora were rotated as intended. The mean obtained rotation was 26.3° (95% confidence interval [CI]: 23.5-29.0) and the mean predicted rotation was 28.2° (95% CI: 26.9-29.5) (p > 0.82). The mean axial distraction was 19.5 mm (95% CI: 17.7-21.3). The predicted rotation of the femora was similar to the obtained values on CT and by goniometer. The obtained rotation occurred as a result of an axial distraction of approximately 2 cm. This suggests a potential for controlled rotation of the femur based on the circumference of the bone and plate dimensions that occurs simultaneously with axial distraction. Clinical significance: These findings suggest a possible clinical application in the treatment of maltorsion in children by guided growth, where theplate design guides the bone into torsional axial growth correcting the deformity.

Does Retrograde Femoral Nailing through a Normal Physis Impair Growth? An Experimental Porcine Model.

MATERIALS AND METHODS: The study was carried out using an experimental porcine model. Eleven juvenile female porcines were randomized for insertion of a retrograde femoral nail in one limb. The other limb acted as a control. The animals were housed for 8 weeks before the nail was removed and housed for 8 additional weeks, that is, 16 weeks in total. Growth was assessed by interphyseal distance on 3D magnetic resonance imaging (MRI) after 16 weeks and the operated limb was compared to the non-operated limb. Histomorphometric analysis of the physeal canal was performed. RESULTS: No difference in longitudinal growth was observed when comparing the operated femur to the non-operated femur using MRI after 16 weeks. No osseous tissue crossing the physis was observed on MRI or histology. The empty canal in the physis after nail removal was filled with fibrous tissue 16 weeks after primary surgery. CONCLUSION: Growth was not impaired and no bone bridges were seen on MRI or histology 16 weeks after insertion and later removal of the retrograde femoral nail. CLINICAL SIGNIFICANCE: The insertion of a retrograde intramedullary femoral nail centrally through the physis and later removal might be safe, however, long-term follow-up is needed. AIM AND OBJECTIVE: The insertion of an intramedullary nail may be beneficial in certain cases of leg length discrepancy (LLD) in children. However, it is unknown if the physeal injury due to the surgery may cause bone bridge formation and thereby growth arrest after removal. This study aimed to assess longitudinal interphyseal growth 16 weeks after insertion and later removal of a retrograde femoral nail passing through the physis. Moreover, to analyse the tissue forming in the empty physeal canal after removal of the nail. HOW TO CITE THIS ARTICLE: Abood AA, Rahbek O, Olesen ML, et al. Does Retrograde Femoral Nailing through a Normal Physis Impair Growth? An Experimental Porcine Model. Strategies Trauma Limb Reconstr 2021;16(1):8-13.

Removal of broken PRECICE Stryde intramedullary lengthening nails.

This paper describes two different techniques for removal of broken Precice Stryde intramedullary bone lengthening nails, which unlike trauma nails are solid containing mechanical components. Consequently, surgeons face unique challenges when these implants brake within medullary canal. Here, we present our surgical approach for removal of three broken implants. In one patient (46kg) both Ø10mm femoral Stryde implants (max. weight allowance 68kg) broke through the proximal locking screw hole preoperatively on the right side and intraoperatively on the left side (413 and 504 days after index surgery respectively). The third Ø11.5 femoral nail broke through the area containing the magnet (55kg patient, 325 days after index surgery). LEVEL OF EVIDENCE: IV.

Autologous cartilage and fibrin sealant may be superior to conventional fat grafting in preventing physeal bone bridge formation - a pilot study in porcines.

PURPOSE: The article compares physeal recovery after insertion of autologous cartilage and a conventional fat graft in a standardized porcine physeal gap model. Presence of a bone bridge was the primary outcome. METHODS: Ten porcines in two groups of five were included in a paired design. A standardized physeal gap in the distal femur was made in all animals. One group (n = 5) was randomized for deposition of autologous cartilage and a Tisseel® or Tisseel® alone. The autologous cartilage was harvested from the femoral articular surface. The other group was randomized for fat grafting or no grafts at all. All animals were housed for 14 weeks. Magnetic resonance imaging (MRI) was performed at 14 weeks prior to euthanasia. The physis was harvested for histology. RESULTS: MRI - Three bone bridges were seen in the fat grafted gaps. All empty gaps formed a bone bridge. No gaps filled with autologous cartilage and Tisseel® resulted in bone bridges. One gap filled with Tisseel® only caused a bone bridge. Histology - The cartilage grafted gaps recovered with physeal-like cartilaginous tissue in histological analysis. CONCLUSIONS: Fat grafts seems ineffective in preventing bone bridges. The use of autologous cartilage may be superior to the current treatment. However, donor site complications were not investigated. The study serves as a proof of concept study and requires further investigation. LEVEL OF EVIDENCE: III.

[Diagnosis of complete transphyseal separation of the distal humerus].

Transphyseal separation of the distal humerus is a rare injury. Trauma, battered child syndrome and birth-related injuries are amongst the most common causes of the injury. This case report illustrates the importance of applying proper imaging and analysis to detect the injury. However, the diagnosis can be missed on conventional radiographs due to the cartilaginous elbow in infants. Instead, magnetic resonance imaging, artrography or ultra-sound can be applied to detect the injury. In this case, the infant was treated non-operatively with good clinical outcome.

The Joint Angle Tool for Intraoperative Assessment of Coronal Alignment of the Lower Limb.

AIM: Presentation of the joint angle tool (JAT), a low-cost goniometer for intraoperative assessment of the lower limb alignment. BACKGROUND: Intraoperative assessment of coronal alignment is important when performing corrective osteotomies around the knee and ankle, limb lengthening, and trauma surgery. JAT provides surgeons with information about the anatomic and mechanical axes intraoperatively based on true anteroposterior radiographs. TECHNIQUE: JAT consists of pre-printed joint orientation angles of the anatomic and mechanical axis including normal variations on a plastic sheet. It is placed on the screen of the image intensifier after obtaining a true anteroposterior image. The pre-printed joint orientation angles can assist the surgeons intraoperatively in achieving the pre-planned axis correction. Here, its feasibility is demonstrated in four cases. CONCLUSION AND CLINICAL SIGNIFICANCE: JAT is a modified goniometer that allows intraoperative assessment of the mechanical and anatomic axis. JAT is applicable throughout the entire surgical procedure irrespective of the method of internal fixation and may provide additional reassurance of correct alignment. JAT consists of a plastic sheet with printed joint orientation angles and their normal variation. JAT is freely available from profeedback.dk/JAT/JAT.pdf for use and modification according to the Creative Commons license (CC BY-SA 4.0) if this paper is attributed. HOW TO CITE THIS ARTICLE: Abood AA-H, Petruskevicius J, Vogt B, et al. The Joint Angle Tool for Intraoperative Assessment of Coronal Alignment of the Lower Limb. Strategies Trauma Limb Reconstr 2020;15(3):169-173.