Comparison of the Efficacy of Human Umbilical Cord-Derived and Bone Marrow Aspirate Concentrate Mesenchymal Stem Cells for Cartilage Repair Defects of the Knee via Arthroscopic Implementation on Scaffolds in a Retrospective Study.

Injuries to the articular cartilage of the human knee joint, commonly resulting from trauma, inflammation, or age- and activity-related wear and tear, have significant implications, primarily leading to osteoarthritis (OA). Conservative treatments for such injuries often yield suboptimal clinical outcomes. Surgical interventions using current methods may not consistently provide satisfactory results, largely due to the formation of low-quality scar tissue lacking the biomechanical properties of hyaline cartilage. In this retrospective study, we compared the results of two promising methods for regenerating cartilage defects in the knee joints using scaffolds soaked with stem cells of different origins: bone marrow aspirate concentrate mesenchymal stem cells (BMAC-MSCs) and human umbilical cord-derived mesenchymal stem cells (hUCB-MSCs). We evaluated 39 patients (39 knees, hUCB-MSCs: 20 knees, BMAC: 19 knees) at the 12-month follow-up using VAS, KOOS, Lysholm scales and radiologically with M-MOCART 2.0 score. The analysis demonstrated substantial overall improvement in both groups, notably reflected in enhanced quality of life for the patients. Interestingly, the final scores in the hUCB-MSCs group were comparable to those in the BMAC-MSCs group, with no statistically significant differences observed, despite variations in preoperative age and lesion size. Notably, the hUCB-MSCs group consisted of significantly older individuals with larger lesion sizes. Both procedures were found to be safe, and improvement was observed in both groups, which holds promise for future clinical investigations.

Translation and rotation analysis based on stress MRI for the diagnosis of anterior cruciate ligament tears.

BACKGROUND: Due to the increasing need for a detailed biomechanical analysis of anterior cruciate ligament (ACL) lesions, the aim of the study was to develop a method of direct measurement of the three-dimensional tibial translation and rotation based on stress MRI. METHODS: For the purpose of the study, thirty patients with acute ACL rupture and 17 healthy control subjects were selected. Based on clinical examination, they were qualified for MRI examination using the Arthroholder Device prototype to perform anterior tibial translation. Each examination was performed at 30° of knee flexion, initially without tibia translation and then using the force applied to the calf of 80 N. The femur and tibia were separately registered using rigid local SimpleITK landmark refinement; translation and rotation parameters were then calculated using the 3D transformation algorithms. The significance level was set at 0.05. RESULTS: Initially, the device and method for obtaining the parameters of the 3D translation and rotation were validated. The pooled Standard Deviation for translation parameters was 0.81 mm and for rotation parameters 0.87°. Compared to the control group, statistically significant differences were found in parameters such as Anterior Shift [(median ± interquartile range) 3.89 mm ±6.55 vs. 0.90 mm ±2.78, P=0.002238] and External Rotation (-0.55° ±3.88 vs. -2.87° ±2.40, P=0.005074). Statistically significant correlations were observed in combined groups between Anterior Shift and parameters such as External Rotation (P=0.001611), PCL Tibial Attachment Point (pPCL) Anterior Shift (<0.000001), Rolimeter Measurement (P=0.000016), and Side-to-Side Difference (SSD) (P=0.000383). A significant statistical correlation was also observed between External Rotation and parameters such as Rolimeter (P=0.02261) and SSD (P=0.03458). CONCLUSIONS: The analysis of the anterior tibia translation using stress MRI and the proposed three-dimensional calculation method allows for a detailed analysis of the tibial translation and rotation parameters. The correlations showed the importance of external rotation during anterior tibial translation.

All-Arthroscopic Treatment of Schatzker Type III Lateral Tibial Plateau Fracture Without Fluoroscopy.

Tibial plateau fracture treatment remains challenging for orthopaedic surgeons around the world, especially in case of type III fractures according to the Schatzker classification, which are a pure depression of the lateral tibial plateau. Whereas open surgical procedures are associated with increased soft-tissue trauma because of the extent of the surgical approach and do not always allow for proper visualization of the fracture site, arthroscopic-assisted surgeries have been proven to have benefits over the former in terms of minimizing soft-tissue trauma, improved visual control of the fracture reduction, and the time of recovery. Most arthroscopic techniques, however, require using fluoroscopy. We present an all-arthroscopic procedure for Schatzker type III lateral tibial plateau fractures with using a trans-septal portal for visualization, which does not demand fluoroscopy.

Possible Approaches to Endoscopic Treatment of Popliteal Cysts: From the Basics to Troublesome Cases.

Popliteal cysts can be an oppressive symptom in patients with concomitant intra-articular knee pathologies. Because isolated treatment of intra-articular lesions is usually not sufficient to resolve the problems associated with a large symptomatic popliteal cyst, a popliteal cyst should be concurrently addressed with other knee pathologies to maximize patient outcomes. Conservative treatment and open surgical excision are associated with high rates of recurrence, so arthroscopic techniques are the preferred treatment options for recalcitrant cases. Arthroscopic communication-enlargement surgery with cyst wall removal seems to be the most effective. We present a simple and effective basic technique for arthroscopic popliteal cyst treatment and some approaches that allow management of the more demanding cases.

Surgical repair of osteochondral lesions of the talus using biologic inlay osteochondral reconstruction: Clinical outcomes after treatment using a medial malleolar osteotomy approach compared to an arthroscopically-assisted approach.

BACKGROUND: Surgical treatment of osteochondral lesions of the talus affecting the medial aspect of the talar dome is typically performed using medial malleolar osteotomy to optimize access. This study compares clinical outcomes of lesions repaired using biologic inlay osteochondral reconstruction in patients who did or did not undergo medial malleolar osteotomy, depending on defect dimensions. METHODS: Patients treated for osteochonral lesions of the talus through a medial mallolar approach or arthroscopically-assisted approach were prospectively followed. Assessment tools consisted of the visual analogue scale (VAS) and the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot score (AOFAS). The magnetic resonance observation of cartilage repair tissue (MOCART) score was used postoperatively. RESULTS: Data for 24 patients (mean age 34years, mean follow-up 22 months) was analyzed. Mean preoperative/final AOFAS and VAS in those who underwent osteotomy were 57.7/81.2 and 5.7/1.9 (p<0.001), respectively. In those who underwent arthroscopically-assisted reconstruction, mean preoperative/final AOFAS and VAS were 54.4/84.0 and 7.6/2.0 (p<0.001), respectively. There was no difference in mean MOCART score (p=0.662) for those treated with osteotomy (67.3) compared to those without (70.8). CONCLUSIONS: Osteochondral lesions of the talar dome can be treated successfully by biological inlay osteochondral reconstruction technique without medial malleolar osteotomy, with good to excellent clinical outcomes expected. MRI demonstrates good integration of the graft into surrounding tissue.

Arthroscopic Cartilage Lesion Preparation in the Human Cadaveric Knee Using a Curette Technique Demonstrates Clinically Relevant Histologic Variation.

PURPOSE: To examine the quality of arthroscopic cartilage debridement using a curette technique by comparing regional and morphologic variations within cartilage lesions prepared in human cadaveric knee specimens for the purpose of cartilage repair procedures. A secondary aim was to compare the histologic properties of cartilage lesions prepared by surgeons of varying experience. METHODS: Standardized cartilage lesions (8 mm × 15 mm), located to the medial/lateral condyle and medial/lateral trochlea were created within 12 human cadaver knees by 40 orthopaedic surgeons. Participants were instructed to create full-thickness cartilage defects within the marked area, shouldered by uninjured vertical walls of cartilage, and to remove the calcified cartilage layer, without violating the subchondral plate. Histologic specimens were prepared to examine the verticality of surrounding cartilage walls at the front and rear aspects of the lesions, and to characterize the properties of the surrounding cartilage, the cartilage wall profile, the debrided lesion depth, bone sinusoid access, and the bone surface profile. Comparative analysis of cartilage wall verticality measured as deviation from perpendicular was performed, and Spearman's rank correlation analysis was used to examine associations between debrided wall verticality and surgeon experience. RESULTS: Mean cartilage wall verticality relative to the base of the lesion was superior at the rear aspect of the lesion compared to the front aspect (12.9° vs 29.2°, P < .001). Variability was identified in the morphology of the surrounding cartilage (P < .001), cartilage wall profile (P = .016), debrided lesion depth (P = .028), bone surface profile (P = .040), and bone sinusoid access (P = .009), with sinusoid access identified in 42% of cases. There was no significant association of cartilage lesion wall verticality and surgeon years in practice (rs = 0.161, P = .065) or arthroscopic caseload (rs = -0.071, P = .419). CONCLUSIONS: Arthroscopic cartilage lesion preparation using standard curette technique in a human cadaveric knee model results in inferior perpendicularity of the surrounding cartilage walls at the front aspect of the defect, compared to the rear aspect. This technique has shown significant variability in the depth of debridement, with debridement depths identified as either too superficial or too deep to the calcified cartilage layer in more than 60% of cases in this study. Surgeon experience does not appear to impact the morphologic properties of cartilage lesions prepared arthroscopically using ring curettes. CLINICAL RELEVANCE: To optimize restoration of hyaline-like cartilage tissue, careful attention to prepared cartilage lesion morphology is advised when arthroscopically performing cartilage repair, given the tendency for standard curette technique to create inferior verticality of cartilage walls at the front of the lesion, and the variable depth of debridement achieved.

Cartilage Repair in the Knee Using Umbilical Cord Wharton's Jelly-Derived Mesenchymal Stem Cells Embedded Onto Collagen Scaffolding and Implanted Under Dry Arthroscopy.

Cell-based cartilage repair procedures are becoming more widely available and have shown promising potential to treat a wide range of cartilage lesion types and sizes, particularly in the knee joint. More recently, techniques have evolved from 2-step techniques that use autologous chondrocyte expansion to 1-step techniques that make use of mesenchymal stem cells (MSCs) embedded onto biocompatible scaffolding. Our 1-step technique has been further developed to provide cell-based cartilage repair using MSCs that have the potential to be used in an off-the-shelf manner, without the need for autologous tissue harvest. Precursor MSCs can be isolated in abundance from the Wharton's jelly of umbilical cord tissue. These cells have been shown to have the desired capacity for proliferation, differentiation, and release of trophic factors that make them an excellent candidate for use in the clinical setting to provide cell-based restoration of hyaline-like cartilage. Although allogeneic in nature, these cells stimulate little or no host immune response and can be stored for long periods while maintaining viability. We present a technique of cartilage repair in the knee using Wharton's jelly-derived MSCs embedded onto scaffolding and implanted in a minimally invasive fashion using dry arthroscopy.

Morphologic Properties of Cartilage Lesions in the Knee Arthroscopically Prepared by the Standard Curette Technique Are Inferior to Lesions Prepared by Specialized Chondrectomy Instruments.

BACKGROUND: Cartilage lesion preparation is an important component to cartilage repair procedures, given the effect of prepared lesion morphology on the formation of durable and well-integrated repair tissue. PURPOSE: To compare the quality of arthroscopic cartilage lesion debridement performed by (1) the standard curette (SC) technique and (2) specialized chondrectomy (CM) instruments, to provide technical guidance for optimization of cartilage lesion preparation in the setting of arthroscopic cartilage repair. STUDY DESIGN: Controlled laboratory study. METHODS: Articular cartilage lesions of standardized size (8 × 15 mm) were demarcated within the trochlea and femoral condyles of 20 human cadaver knee specimens. Orthopaedic surgeons performed arthroscopic lesion preparation using 2 techniques that consisted of SC preparation and preparation by CM instruments. A histologic comparative analysis was performed within each treatment group and between treatment groups to evaluate the morphology of prepared cartilage defects. RESULTS: The mean angle deviation from perpendicular of the cartilage wall at the front of the prepared cartilage lesions was significantly greater in the SC group versus the CM group (29.8° ± 21.4° vs 7.7° ± 7.6°, P < .001). In lesions prepared via the SC technique, the cartilage walls at the front of the prepared lesions were significantly less perpendicular than the cartilage walls at the rear of the lesions (29.8° ± 21.4° vs 11.0° ± 10.3°, P < .001), whereas lesions prepared by the CM technique demonstrated comparable verticality of surrounding cartilage walls at the front and rear aspects of the lesions (7.7° ± 7.6° vs 9.4° ± 12.3°, P = .827). Depth of lesion debridement was accomplished to the target level by the CM technique in 86% of prepared lesions, compared with 34% of lesions in the SC group. The prepared cartilage wall profile was characterized as the most ideal morphology in 55% of prepared lesions in the CM group, as opposed to 10% in the SC group. CONCLUSION: Arthroscopic cartilage lesion preparation with SC instruments results in superior perpendicularity of surrounding cartilage walls to subchondral bone and greater consistency of debrided lesion depth, as compared with the standard debridement technique with curettes. CLINICAL RELEVANCE: Arthroscopic preparation using standard curette technique leads to suboptimal morphologic characteristics of prepared lesions that likely affect the quality of repair tissue, compared to preparation using specialized chondrectomy instruments.

Biological reconstruction of large osteochondral lesions of the talar dome with a modified "sandwich" technique-Midterm results.

BACKGROUND: Surgical treatment for large osteochondral lesions of the talar dome (OLTD) must restore the convexity and curvature of the talus. Here, we present midterm results and describe the modified "sandwich" reconstruction procedure. Bone defects were restored using a biological inlay consists of autologous bone chips that were mixed with bone marrow concentrate and fibrin glue and covered with a xenogeneic collagen membrane infiltrated with bone marrow concentrate and stabilized by fibrin glue. METHODS: Ten patients who were treated using a modified "sandwich" OLTD reconstruction were assessed after an average follow-up period of 46.4 (±18) months, using the clinical American Orthopaedic Foot and Ankle Society Ankle Hindfoot Scale (AOFAS) score and radiological magnetic resonance observation of cartilage repair tissue (MOCART) score. RESULTS: The mean AOFAS score increased significantly from 58.3 (±8.5) points to 81.8 (±15.5) points as well the mean VAS score reduced significantly from 5.58 (±0.97) to 1.83 (±0.93) points. The average MOCART score was 69.5% (±16.7%) in the final follow-up. CONCLUSIONS: The presented modified "sandwich" technique permanently recreates the convexity and curvature in large osteochondral lesions of the talar dome with a single step surgical procedure.

Biologic Inlay Osteochondral Reconstruction: Arthroscopic One-Step Osteochondral Lesion Repair in the Knee Using Morselized Bone Grafting and Hyaluronic Acid-Based Scaffold Embedded With Bone Marrow Aspirate Concentrate.

Cartilage injury of the knee that is associated with significant subchondral bone loss can result in great morbidity, and treatment options that provide durable repair are limited. Osteochondral autograft and allograft reconstruction of these lesions has been used extensively; however, these techniques often require a more invasive surgical exposure, and restoring the natural articular surface radius of curvature can be challenging, particularly in larger lesions. Cell-based repair of these lesions, using autologous chondrocytes in conjunction with bone grafting, has been used with success, although this procedure requires the patient to undergo 2 operations, and access is often restricted due to the high associated costs. Comparable medium-term clinical outcomes have been shown with scaffold-associated mesenchymal stem cell grafting, and this cell-based procedure may also be performed arthroscopically to minimize patient morbidity. In cases of cartilage injury associated with bone loss, this procedure has great potential to repair osteochondral injury when used in conjunction with bone grafting. We present the one-step arthroscopic technique of biologic inlay osteochondral reconstruction in the knee, using an autologous bone graft and a hyaluronic acid-based scaffold embedded with bone marrow aspirate concentrate, to treat full-thickness cartilage lesions associated with significant subchondral bone loss.

Results of Arthroscopic Ankle Arthrodesis with Fixation Using Two Parallel Headless Compression Screws in a Heterogenic Group of Patients.

BACKGROUND: As orthopedic surgeons become skilled in ankle arthroscopy technique and evidence -based data is supporting its use, arthroscopic ankle arthrodesis (AAA) will likely continue to increase, but stabilization methods have not been described clearly. We present a technique for two parallel 7.3-mm headless compression screws fixation (HCSs) for AAA in cases of ankle arthritis with different etiology, both traumatic and non-traumatic, including neuromuscular and inflammatory patients. MATERIALS AND METHODS: We retrospectively verified 24 consecutive patients (25 ankles) who underwent AAA between 2011 and 2015. The average follow-up was 26 months (range 18 to 52 months). Arthrodesis was performed in 16 patients due to posttraumatic arthritis (in 5 as a sequela of pilon, 6 ankles, 3 tibia fractures, and 2 had arthritis due to chronic instability after lateral ligament injury), in 4 patients due to neuromuscular ankle joint deformities, and in 4 patients due to rheumatoid arthritis. RESULTS: Fusion occurred in 23 joints (92%) over an average of 12 weeks (range 6 to 18 weeks). Ankle arthrodesis was not achieved in 2 joints (8%), both in post-pilon fracture patients. The correct foot alignment was not achieved in 4 feet (16%). None of the treated patients required hardware removal. CONCLUSION: The presented technique was effective in achieving a high fusion rate in a variety of diseases, decreasing intra- and post-operative hardware complications while maintaining adequate bone stability.

All-Arthroscopic Autologous Matrix-Induced Chondrogenesis-Aided Repair of a Patellar Cartilage Defect Using Dry Arthroscopy and a Retraction System.

The technique of all-arthroscopic autologous matrix-induced chondrogenesis (AMIC)-aided repair of patellar cartilage lesions using a retraction system and dry arthroscopy has been recently described. We report the first clinical and radiological data at a short-term follow-up. Twelve patients underwent AMIC-aided cartilage repair for a patellar lesion. All steps of the procedure were performed arthroscopically, which include the use of an intra-articularly placed retraction plate for distraction of the patellofemoral joint and evacuation of saline solution for collagen matrix insertion and fixation. Clinical assessment performed before surgery and at a mean follow-up time of 38 months (range: 24-70) included the following scores: Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC), and visual analog scale (VAS). Magnetic resonance imaging was performed at the follow-up examination, including the magnetic resonance observation of cartilage repair tissue (MOCART) score. The mean KOOS and IKDC scores increased significantly (p < 0.01) from 50.3 and 37.4 points preoperatively to 90.1 and 79.4 postoperatively. The VAS score decreased from 7.8 to 2.3 points. Mean MOCART score at follow-up was 58.3 points. Cartilage repair of patellar lesions aided by a retraction system in a dry arthroscopy setup is a promising approach. Further studies are needed to evaluate this procedure and compare it to existing matrix implantation techniques. The level of evidence for the study is 4 (case series).

Dry Arthroscopic Single-Stage Cartilage Repair of the Knee Using a Hyaluronic Acid-Based Scaffold With Activated Bone Marrow-Derived Mesenchymal Stem Cells.

Cartilage lesions of the knee are a frequent finding; however, treatment options that are capable of restoring hyaline-like tissue are not routinely used. Cell-based technology such as autologous chondrocyte implantation may in some cases provide durable cartilage repair, but availability of this procedure is often restricted due to cost constraints. There have been promising outcomes reported with the use of scaffolds seeded with activated bone marrow aspirate concentrate in cases of chondral injury. There are clear advantages to cell-based cartilage repair techniques that are performed as a single-stage procedure, particularly when the repair technology can be used in a minimally invasive manner. We present an arthroscopic technique of cartilage repair using a hyaluronic acid-based scaffold associated with activated bone marrow aspirate concentrate. This technique is a cost-effective, minimally invasive, single-stage procedure that has the potential for routine use in a wide range of cartilage lesion types and locations.

Chondrectomy--Review of Surgical Instrumentation and its Effectiveness.

UNLABELLED: ΒACKGROUND: To present surgical instrumentation used in knee chondrectomy and evaluate its effectiveness - a review of the literature. Surgical removal of joint cartilage, or chondrectomy, has been performed by orthopedists since the 1950s. Initially carried out as an open surgery, it has generally come to be performed arthroscopically. Its aim is to create even and stable cartilaginous edges perpendicular to the joint surface and a suitably prepared bottom of the defect for optimum integration of the cartilaginous regenerate. MATERIAL AND METHODS: In order to present surgical instrumentation used in knee chondrectomy, English-language journals from the years 2010-2013 with an Impact Factor (2013) of at least 2.0 were analyzed. Papers concerning effectiveness and precision of knee chondrectomy according to the instrument used were also analyzed. RESULTS: According to the articles the most popular instruments used to debride chondral defects are open bone curettes (67% of the surgeries), scalpels (35%) and shavers (21%). Open bone curettes were used most frequently in open surgeries (78%), often along with scalpels (49% of the surgeries). In arthroscopic procedures, the most common instruments were shavers (50% of the surgeries) and open bone curettes (49%). CONCLUSIONS: 1. In open chondrectomies, the most frequently used instruments are open bone curettes and scalpels. 2. Of all instrumentation presented in this review, this combination ensures the highest precision, as required by Steadman's criteria, of debriding the edges and bottom of a chondral defect. 3. In arthroscopic procedure, a shaver and an open bone curette is the most frequently used combination. 4. None of the instruments and their combinations used in arthroscopic procedure ensures debridement of the defect in compliance with Steadman's recommendations.

Implantation of a collagen matrix for an AMIC repair during dry arthroscopy.

UNLABELLED: Several arthroscopic cartilage repair techniques in the knee joint require the insertion of a cut-to-shape matrix. Depending on the location and accessibility of the cartilage lesion, this procedure can be challenging. To overcome the limitations of currently used techniques, a novel matrix insertion technique was developed. This technique utilizes an inserter rod and a dedicated guide which can be used in a dry arthroscopy setup. LEVEL OF EVIDENCE: Expert opinion, Level V.

Dry arthroscopy with a retraction system for matrix-aided cartilage repair of patellar lesions.

Several commercially available cartilage repair techniques use a natural or synthetic matrix to aid cartilage regeneration (e.g., autologous matrix-induced chondrogenesis or matrix-induced cartilage implantation). However, the use of matrix-aided techniques during conventional knee joint arthroscopy under continuous irrigation is challenging. Insertion and fixation of the matrix can be complicated by the presence of fluid and the confined patellofemoral joint space with limited access to the lesion. To overcome these issues, we developed a novel arthroscopic approach for matrix-aided cartilage repair of patellar lesions. This technical note describes the use of dry arthroscopy assisted by a minimally invasive retraction system. An autologous matrix-induced chondrogenesis procedure is used to illustrate this novel approach.

Injuries of the distal tibio-fibular syndesmosis.

BACKGROUND: Inuries to distal tibiofibular syndesmosis are common in clinical practice in traumatology and are particularly frequently associated with ankle or high fibular fracture (Maisonneuve fracture). Isolated syndesmotic injuries are less frequently observed--ore often among athletes. Although injuries to ankle syndesmosis are numerous, methods of diagnosis and treatment remain controversial, and present diagnostic and therapeutic challenges. MATERIAL/METHODS: Medical databases PUBMED, MEDLINE EMBASE and OVID were searched by entering the key words such as tibio-fibular syndesmosis, ankle ligaments, ankle injuries, ankle fracture, ankle instability. RESULTS: Almost 200 publications regarding the topic were chosen. Important information on anatomy, causes and mechanisms of injury, diagnostics and current concepts of treatment of the distal tibiotibular syndesmosis were selected. CONCLUSIONS: Proper and early diagnosis and appropriate treatment, either conservative or surgical, is essential for full recovery. Due to numerous controversies regarding diagnosis and treatment of syndesmosis injuries more research is needed to establish strong recommendations for management of such injuries.

Surgical treatment of advanced, stiff neurologic cavovarus foot in adults.

BACKGROUND: Cavovarus foot is a complex, three-dimensional deformity of neuromuscular origin. A rigid cavovarus deformity causes difficulty in walking, instability, fatigue fractures, calluses and trophic ulcers in the overloaded lateral part of the foot and requires wearing orthopaedic shoes. The aim of the study was to evaluate current surgical techniques in the treatment of rigid cavovarus foot in adults. MATERIAL AND METHODS: This paper is a retrospective analysis of 14 patients (15 feet) treated surgically at our centre who presented with advanced cavovarus foot caused by a spectrum of neuromuscular diseases such as Charcot-Marie-Tooth, poliomyelitis, cerebral palsy, myelomeningocele, diabetes (Charcot's neuroarthropathy), sequelae of strokes and CNS injuries, compartment syndrome and inveterate sciatic nerve injuries. Average patient age was 53 years. Average follow-up period was 24 months (range: 18-58). The AOFAS scoring system was used to assess treatment results. RESULTS: The mean AOFAS score before surgery was 24 (range: 8-35) points and increased to 60 (range: 40-76) points after surgery. A stable, plantigrade, painless foot was achieved in all treated patients. CONCLUSIONS: 1. Surgical treatment of advanced cavocarus foot of neuromuscular origin should be carried out in a staged process with reassessment and adaptation of subsequent stages rather than following a rigid scheme. 2. The surgeon must be familiar with a number of techniques and procedures in order to correct the bony deformity and achieve muscle imbalance correction in a single-stage surgery.