Questions about Using the Induced Membrane Technique to Manage Cases of Congenital Tibial Pseudarthrosis.

The induced membrane technique is an innovative approach for repairing critical bone defects and has been applied recently in patients with congenital pseudarthrosis of the tibia (CPT). CPT is frequently associated with neurofibromatosis type 1 (NF1). Here, we briefly describe the clinical results of the induced membrane technique in NF1-deficient patients with CPT and in an animal model of CPT. Furthermore, we discuss the hypotheses used to explain inconsistent outcomes for the induced membrane technique in CPT-especially when associated with NF1.

Anatomical variations in the sensory innervation of the dorsal surface of the first digit space, a cadaveric study with clinical consequences.

INTRODUCTION: Radial nerve palsy is a classical complication of a humeral shaft fracture. In clinical practice, motor palsy of the radial nerve is sometimes observed without an abnormality felt in the sensory territory. HYPOTHESIS: We hypothesised that this dissociation between sensory and motor involvement is related to anatomical variations of the sensory innervation of the dorsal surface of the first digit space, thus, we decided to study the nature and frequency of these variations. MATERIAL AND METHOD: A cadaveric study was conducted on 24 upper limbs to analyse the truncal origin of the sensory branches innervating the dorsal surface of the first digit space. RESULTS: The sensory branch of the radial nerve (SBRN) participated in the innervation of the dorsal surface of the first digit space in 22 limbs, an anatomical variation was present in 2 cases with a mixed innervation by the SBRN and the lateral cutaneous nerve of forearm (LCNF) in 1 case and singular innervation by LCNF, with no SBRN involvement, in 1 case. Communications between SBRN and LCNF were found in 7 cases. DISCUSSION: Pure motor radial damage, without a sensory deficit of the dorsal surface of the first digit space, does not preclude a complete traumatic injury of the radial nerve. The sensory innervation of this region can be relayed by a branch of the LCNF. LEVEL OF EVIDENCE: IV; cadaveric study.

Learning curve and influencing factors of performing microsurgical anastomosis: a laboratory prospective study.

Despite being a critical component of any cerebrovascular procedure, acquiring skills in microsurgical anastomosis is challenging for trainees. In this context, simulation models, especially laboratory training, enable trainees to master microsurgical techniques before performing real surgeries. The objective of this study was to identify the factors influencing the learning curve of microsurgical training. A prospective observational study was conducted during a 7-month diploma in microsurgical techniques carried out in the anatomy laboratory of the school of surgery. Training focused on end-to-end (ETE) and end-to-side (ETS) anastomoses performed on the abdominal aorta, vena cava, internal carotid and jugular vein, femoral artery and vein, caudal artery, etc. of Wistar strain rats under supervision of 2 expert anatomical trainers. Objective and subjective data were collected after each training session. The 44 microsurgical trainees enrolled in the course performed 1792 anastomoses (1577 ETE, 88%, vs. 215 ETS, 12%). The patency rate of 41% was independent from the trainees' surgical background and previous experience. The dissection and the temporary clamping time both significantly decreased over the months (p < 0.001). Technical mistakes were independently associated with thrombosis of the anastomoses, as assessed by the technical mistakes score (p < 0.01). The training duration (in weeks) at time of each anastomosis was the only significant predictor of permeability (p < 0.001). Training duration and technical mistakes constituted the two major factors driving the learning curve. Future studies should try and investigate other factors (such as access to wet laboratory, dedicated fellowships, mentoring during early years as junior consultant/attending) influencing the retention of surgical skills for our difficult and challenging discipline.

Induced membrane technique applied to the forearm: Technical refinement, indications and results of 13 cases.

INTRODUCTION: The unique anatomical characteristics of the forearm bones makes their reconstruction challenging. The aim of this study was to report the surgical methods and results of the induced membrane technique applied to traumatic forearm bone defects. MATERIAL AND METHODS: We evaluated retrospectively a case series of 13 patients operated between 2010 and 2017. The first surgical step consisted of debridement of the fracture site and implantation of a cement spacer with appropriate fixation. The anatomy of the forearm skeleton had to be restored. The second step, done 6 weeks later, consisted of removing the cement spacer and applying cancellous bone autograft harvested from the iliac crest. The outcome measures were radiological bone union, need for surgical revision, and postoperative wrist range of motion. RESULTS: All 13 patients were men, with a mean age of 39 years (18-67). The average follow-up was 2.5 years. Eleven patients were suffering from a nonunion and two from a post-traumatic bone defect. Six patients had an identified preoperative infection. Three patients had previously undergone an unsuccessful treatment for their nonunion with bone addition. The maximum length of bone reconstruction was 12 cm. Union was achieved in 12 of 13 patients in a mean of 5 months (3-8). The other patient died during the postoperative course. Two patients needed revision surgery: ulnar shortening osteotomy (1 case) and additional tendon reconstruction (1 case). The mean pronosupination range was 123° on average (55-180°). The mean flexion-extension range was 106° (90-130°). CONCLUSION: The induced membrane technique is a reliable reconstruction technique that is well suited to reconstruction of the forearm skeleton. LEVEL OF EVIDENCE: IV, retrospective study.

Modified Masquelet Technique Using Allogeneic Graft for a Gustilo-Anderson Type III-A Open Fracture of the Femur with an 8 cm Bone Defect.

The induced membrane technique was initially described by Masquelet et al. in 1986 as a treatment for tibia nonunion; then, it became one of the established methods in the management of bone defects. Several changes have been made to this technique and have been used in different contexts and different methodologies. We present the case of a 16-year-old girl admitted to our department for a polytrauma after a motorcycle accident. She presented a Gustilo III-A open fracture of the right femoral shaft with a large bone defect of 8 centimeters that we treated with a modified Masquelet technique. In the first stage, an Open Reduction and Internal Fixation of the fracture was made using a 4,5 mm Dynamic Compression Plate and a PMMA cement was inserted at the bone defect area. The second stage was done after 11 weeks, and the defect area was filled exclusively with bone allograft from a bone bank. Complete bony union was seen at 60 weeks of follow-up. After the removal of the implants by another surgeon, the patient presented an atraumatic fracture of the neoformed bone that we treated with intramedullary femoral nailing associated with a local autograft using reaming debris. A complete bony union was achieved after 12 weeks with a complete range of motion of the hip and knee. The stability given to the fracture is essential because it influences the quality of the induced membrane and Masquelet has recommended high initial fixation rigidity to promote incorporation of the graft. It is recommended to delay the second stage of this technique after 8 weeks, especially in femoral reconstruction, to optimize the quality of the induced membrane. Several studies used a modified induced membrane technique to recreate a traumatic large bone defect, and all of them used an autologous bone graft alone or an enriched bone graft. In this case, the use of allograft exclusively seems to be as successful as an autologous or enriched bone graft. Now, with the advent of bone banks, it is possible to get an unlimited amount of allograft, so additional research and large studies are necessary before giving recommendations.

Induced membrane technique: a critical literature analysis and proposal for a failure classification scheme.

The reconstruction of long-bone segmental defects remains challenging, with the three common methods of treatment being bone transport, vascularized bone transfer, and the induced membrane technique (IMT). Because of its simplicity, replicability, and reliability, usage of IMT has spread all over the world in the last decade, with more than 300 papers published in the PubMed literature database on this subject so far. Most of the clinical studies have reported high rates of bone union, yet some also include more controversial results with frequent complications and revision surgeries. At the same time, various experimental research efforts have been designed to understand and improve the biological properties of the induced membrane. This literature review aims to provide an overview of IMT clinical results in terms of bone union and complications and to compare them with those of other reconstructive procedures. In light of our findings, we then propose an original classification scheme of IMT failures distinguishing between preventable and nonpreventable failures.

Repeated Induced-Membrane Technique Failure without Infection: A Series of Three Consecutive Procedures Performed for a Single Femur Defect.

A 40-year-old male was treated using the induced-membrane technique (IMT) for a noninfected, 9 cm long femoral bone defect complicating a lengthening procedure. The interesting case feature lies in the three consecutive IMT procedures that were necessary to achieve complete bone repair in this unusual clinical situation. The first procedure failed because of the lack of graft revascularization likely related to an induced-membrane (IM) alteration demonstrated by histological observations. The second IMT procedure led to partial graft integration interrupted by the elongation nail breakage. At last, the third procedure fully succeeded after nail exchange and iterative iliac bone grafting. Complete bone union was achieved with a poor functional recovery one year after the last procedure and four years following the first cement spacer implantation. By means of clinical and histological observations, we demonstrated that the first and the second IMT failures had two distinct origins, namely, biological and mechanical causes, respectively. Although simple, a successful IMT procedure is not so easy to complete.

Induced membrane technique with sequential internal fixation: use of a reinforced spacer for reconstruction of infected bone defects.

PURPOSE: To evaluate a novel sequential internal fixation strategy using a reinforced spacer for infected bone defect reconstruction by the induced membrane technique (IMT). METHODS: A retrospective case study was performed among patients treated for infected bone defects by applying this strategy. Following radical debridement, temporary stabilization was provided by a massive cement spacer combined with minimal intramedullary fixation during step 1. Definitive internal fixation was performed together with bone grafting at step 2. RESULTS: Eight patients with a mean age of 58 years were reviewed. The mean bone defect length was 8.8 cm. The spacer armature mostly consisted of elastic nails and Steinmann pins. Iterative debridement was required in one case after step 1. The mean interval between steps was 12 weeks. Definitive internal fixation was performed by intramedullary nailing (n = 4) or plating (n = 4). At a mean follow-up of 21 months, bone union was achieved in seven cases without additional bone grafting or infection recurrence. CONCLUSIONS: Sequential internal fixation using a reinforced cement spacer seems to be a valuable option for avoiding external fixation between IMT steps and limiting the recurrence of infection.

The Masquelet technique: Current concepts, animal models, and perspectives.

Bone reconstruction within a critical-sized defect remains a real challenge in orthopedic surgery. The Masquelet technique is an innovative, two-step therapeutic approach for bone reconstruction in which the placement of a poly (methylmethacrylate) spacer into the bone defect induces the neo-formation of a tissue called "induced membrane." This surgical technique has many advantages and is often preferred to a vascularized bone flap or Ilizarov's technique. Although the Masquelet technique has achieved high clinical success rates since its development by Alain-Charles Masquelet in the early 2000s, very little is known about how the process works, and few animal models of membrane induction have been developed. Our successful use of this technique in the clinic and our interest in the mechanisms of tissue regeneration (notably bone regeneration) prompted us to develop a surgical model of the Masquelet technique in rats. Here, we provide a comprehensive review of the literature on animal models of membrane induction, encompassing the defect site, the surgical procedure, and the histologic and osteogenic properties of the induced membrane. We also discuss the advantages and disadvantages of those models to facilitate efforts in characterizing the complex biological mechanisms that underlie membrane induction.

Induced-membrane treatment of refractory humeral non-union with or without bone defect.

INTRODUCTION: Treatment of humeral non-union with or without bone defect is complex, with non-negligible rates of complication and failure. Few reports focused on management of treatment failure. OBJECTIVE: The study hypothesis was that the induced-membrane technique associated in a 2-stage strategy to internal fixation provides systematic bone healing in refractory humeral non-union. MATERIAL AND METHODS: The study included 15 patients, with a median age of 46.6 years, with humeral non-union of a mean 24 months' progression and mean history of 3 attempted revision surgeries. Seven patients showed bone defect, exceeding 5cm in 2 cases. Six had history of radial palsy. RESULTS: Consolidation was achieved in all cases, at a mean 4.6 months. Ten patients underwent radial nerve transposition, 6 of whom had shown radial motor nerve palsy; all recovered within 2 to 5 months. There was 1 case of superficial infection, and 1 of seroma. DISCUSSION: The induced-membrane technique ensures bone healing due to the biological properties of the membrane; the main drawback is the need for 2-stage surgery. When bone defect exceeds 5cm, a multi-perforated fibula segment can be placed inside the membrane to increase primary stability and enhance bone integration. CONCLUSION: The induced-membrane technique is suited to humeral non-union, with or without bone defect. The 2-stage strategy is mandatory in case of suspected latent infection. In the 2-stage procedure, anteromedial radial nerve transposition facilitates the bone-graft stage. LEVEL OF EVIDENCE: IV, retrospective study.

Anatomy of the posterior branch of the medial antebrachial cutaneous nerve: A cadaveric study.

PURPOSE: The posterior branch of the medial antebrachial cutaneous nerve (MACN) is at risk to be damaged during cubital tunnel surgery. The purpose of this study was to identify the location of the posterior branch of the MACN (PBMACN) in relation to surgical landmarks pertinent in cubital tunnel surgery. METHODS: We performed an anatomical study on 20 limbs from 13 fresh cadavers. The nerve was dissected from 10cm proximal to 10cm distal of the medial epicondyle. We measured the distance between the nerve and the medial epicondyle, and also the distance separating the PBMACN from the ulnar nerve passage between the two heads of the flexor carpi ulnaris. Measurements were performed with the elbow at 45° and 90° of flexion, as well as in full pronation and supination. RESULTS: After its emergence from the main trunk of the MACN, the posterior branch ran anteriorly to the medial epicondyle, taking an oblique direction toward the ulnar shaft. The PBMACN was in average 2.53cm under the medial epicondyle when the elbow was flexed at 45°, and 2.96cm when the elbow was flexed at 90°. Average distance between the PBMACN and the penetrating point of the ulnar nerve within the flexor carpi ulnaris was 1.54cm when the elbow was flexed at 45°, and 1.62cm when the elbow was flexed at 90°. Pronation and supination positions of the forearm did not significantly modify our measurements. CONCLUSIONS: Understanding the position of MACN posterior branch during ulnar nerve release surgery at the elbow may help in preventing iatrogenic injury. According to our measurements, incision and superficial dissection anterior to the medial epicondyle or distal to the ulnar nerve penetrating point between the two heads of the flexor carpi ulnaris should be avoided or done with an elbow flexed at 90°.

Towards Understanding Therapeutic Failures in Masquelet Surgery: First Evidence that Defective Induced Membrane Properties are Associated with Clinical Failures.

The two-stage Masquelet induced-membrane technique (IMT) consists of cement spacer-driven membrane induction followed by an autologous cancellous bone implantation in this membrane to promote large bone defect repairs. For the first time, this study aims at correlating IMT failures with physiological alterations of the induced membrane (IM) in patients. For this purpose, we compared various histological, immunohistochemical and gene expression parameters obtained from IM collected in patients categorized lately as successfully (Responders; n = 8) or unsuccessfully (Non-responders; n = 3) treated with the Masquelet technique (6 month clinical and radiologic post-surgery follow-up). While angiogenesis or macrophage distribution pattern remained unmodified in non-responder IM as compared to responder IM, we evidenced an absence of mesenchymal stem cells and reduced density of fibroblast-like cells in non-responder IM. Furthermore, non-responder IM exhibited altered extracellular matrix (ECM) remodeling parameters such as a lower expression ratio of metalloproteinase-9 (MMP-9)/tissue inhibitor of metalloproteinases (TIMP-1) mRNA as well as an important collagen overexpression as shown by picrosirius red staining. In summary, this study is the first to report evidence that IMT failure can be related to defective IM properties while underlining the importance of ECM remodeling parameters, particularly the MMP-9/TIMP-1 gene expression ratio, as early predictive biomarkers of the IMT outcome regardless of the type of bone, fracture or patient characteristics.

Reconstruction of lateral pinch in an isolated paralysis of the first dorsal interosseous muscle - A new surgical technique.

Lack of function of the first interosseous muscle (FDI) might be responsible for insufficient stabilisation of the index finger during lateral pinch, and may induce disability in hand function. The first cause of FDI palsy is ulnar nerve palsy. We describe a new tendon transfer to reanimate the FDI muscle, using the extensor indicis proprius tendon. The tendon is sectioned at its distal insertion and rerouted in the first extensor tendon compartment. We report one case of isolated first interosseous muscle palsy secondary to direct trauma. Preoperatively, the patient complained of a severe lack of strength during key pinch with an ulnarly deviated index finger. Thirty months postoperatively, the patient recovered active abduction of the index finger and lateral pinch was measured at 5.5kg (54N). Compared to the original Bunnell transfer our technique restores the native moment arm of the FDI muscle and does not require a tendon graft.

Trends in Trapeziometacarpal Implant Design: A Systematic Survey Based on Patents and Administrative Databases.

Hand function is inseparably linked to the condition of the thumb. The trapeziometacarpal (TMC) joint that provides the different movements of opposition is one of the joints most affected by osteoarthritis, which causes an irreversible deformation of the bone. The ideal thumb carpometacarpal implant must restore range of movement, prevent complications, be biocompatible, and have good mechanical properties (ie, low wear, high corrosion resistance, and osteointegration properties where it is anchored in a bone). The integrity of the implant and the surrounding biological structures must be long-lasting and withstand constant stresses induced by the prosthesis. Three main types of implant systems for the thumb are currently clinically available; others are under investigation in human subjects. This systematic review is based on administrative databases, patents, the literature, and information from orthopedic companies. It provides a summary of strategies and design changes and an overview of the biomechanical characteristics of currently available carpometacarpal implants for treating osteoarthritis of the thumb.

A voxel-based method for designing a numerical biomechanical model patient-specific with an anatomical functional approach adapted to additive manufacturing.

Here, we describe an original and efficient geometry design approach, based on voxels resulting in a validated model for printability in additive manufacturing. The proposed approach is also designed to be accessible to non-specialists as it does not require specialist skills in computer-assisted-design (CAD). It focuses on biomedical applications, particularly the geometry design of a configurable digital biomechanical model with selected anatomical features based on medical imaging compatible with customization, as might be needed for prosthetic elements. The methodology is based on two main steps. First, an accessible parametrization to medical employees of a configurable biomechanical model is matched specifically to the patient. The configurable model is designed to palliate any kind of potential lack of information from the Digital Imaging and Communication in Medicine (DICOM) file of the medical imaging or partial topological defects but with the least and sufficient number of parameters. For this purpose, the configurable model is segmented in topological areas with a complexity facing solely the desired specification, without regards of potential numerical errors prior AM such as boundary edges, intersecting faces and non-manifold edges. The second step is the voxel-based modelling, easily accessible for medical employees unfamiliar with CAD. Voxels stores the geometric information in a discrete format to facilitate customization by topological operations such as addition and subtraction. The voxelization representation coupled with a smoothing filter, results in a more realistic, robust and closed triangulated model, freed from errors of printability. This method is presented in the context of a trapezium replacement prosthesis prior to selective laser melting (SLM) and diverse post-treatments.

Perforators of the fibular artery and suprafascial network.

INTRODUCTION: Soft tissue defect on lower limb can result in an intractable wound. Surgeons resort in flaps to cover these injuries. Including fascia as in the case of a fasciocutaneous flap increases survey of the flap. Rising a perforator flap avoids to sacrifice a major vessel whence the nourishing perforator artery is born. We wanted to explore suprafascial distribution of the fibular skin perforator arteries supposing possible to find out a vascular axis composed of anastomoses of the fibular perforator vessels. MATERIALS AND METHODS: Systematic observation was carried out on ten injected legs about the fibular perforator distribution, and especially their suprafascial course. RESULTS: Dissection allowed us to raise in all specimens a large fasciocutaneous paddle including a fine arteriolar vessel connecting fibular perforators. Perforators were isolated along from the leg and we found suprafascial arteriole connecting all perforators from the fibular head to the lateral malleolus. There were a total number of 126 perforators for 10 legs. The mean length of the fibula was 32.9 cm. No perforator was located at more than 2 cm from fibular posterior border. Proximal perforators were closer to posterior fibular side than distal perforators. We found that fibular perforators clustered in the middle and upper third of the leg. CONCLUSION: This study proves the real existence of a microvascular suprafascial axis formed by fibular perforator anastomoses and stretching over the entire length of the fibula, from the fibular head to the distal tip of the lateral malleolus. This suprafascial vascular axis could be an anatomical basis for a fasciocutaneous fibular flap.

A cadaver study into the number of fasciotomies required to decompress the anterior compartment in forearm compartment syndrome.

PURPOSE: There is no typical approach for decompression of forearm compartment syndrome, due to contradictory considerations regarding the characteristics of forearm anterior compartment deep fascia. The main purpose of this study was to determine how many fasciae should be opened to fully decompress the forearm anterior compartment. Further, the compliance of the deep anterior compartment was also investigated, to strengthen our results. METHODS: An experimental study of a laboratory model of acute forearm compartment syndrome was performed. A deep forearm injection of egg white was undertaken to create an acute forearm compartment syndrome in sixteen non-embalmed human forearms from six male and two female donors. The pressure in the superficial and deep anterior compartments was recorded four times, both before and after each fasciotomy and the compliance of the deep anterior compartment was calculated for each step. RESULTS: The first incision of the superficial lamina of the deep fascia was not sufficient to decrease the elevated compartment pressure in the superficial and deep anterior compartments. Whereas the pressures decreased to near-baseline levels, following the fasciotomy of the intermuscular septum observed posterior to the flexor carpi radialis. The last incision of the deep lamina of the deep anterior fascia had no noticeable impact. These observations supported the hypothesis of high compliance of the deep anterior compartment. CONCLUSION: Two successive incisions were necessary to decompress the anterior compartment: the incision of the superficial lamina of the deep fascia and the incision of the intermuscular septum.

A New Synthetic Model for Microvascular Anastomosis Training? A Randomized Comparative Study Between Silicone and Polyvinyl Alcohol Gelatin Tubes.

INTRODUCTION: Assessment of a resident's microsurgical competency with the rodent model remains the current gold standard. However, cost and ethical issues related to animal welfare may limit training opportunities. Therefore, synthetic alternatives such as silicone tubes have been developed to provide easy access to training, shorten the learning curve, and have been incorporated into microsurgical courses as a low-fidelity model for basic skills acquisition. This study compares the use of polyvinyl alcohol (PVA) gelatin tubes with silicone for resident microsurgical training. MATERIAL AND METHODS: Residents were randomized into silicone (S) or PVA (P) groups and underwent the same training. Following basic instruction, microsurgical anastomoses were performed with the rat's aorta or carotid artery or both. Performance was assessed using the Objective Structured Assessment of Technical Skills (OSATS) score and 5 different items to assess the quality of the anastomosis. Posttest questionnaires were also conducted for qualitative assessment of both students' and trainers' experience with silicone and PVA in comparison with rat vessels. RESULTS: OSATS score in Group P was higher than Group S (18.2 ± 2.6 vs 16.6 ± 2.5, p = 0.015). Results of anastomoses were similarly better in Group P based on OSATS score (19.3 ± 1.2 vs 17.7 ± 0.7, p = 0.027). Subjectively, both students and trainers found that PVA tubes resembled the rat aorta more closely than silicone. The number of rats used was also significantly lower in Group P than Group S (65 vs 75 total, p = 0.023). CONCLUSION: PVA gelatin tubes may be a viable alternative to silicone for microsurgical training because this synthetic model mirrors better rat vessels and can improve training performance based on objective assessment while using less animals overall.