Lateral Opening Wedge Research Articles

Medial open wedge osteotomy yields comparable stability to lateral open wedge procedure on the distal femur.

Supracondylar osteotomies are a frequently and successfully used technique in the treatment of coronal plane deformities and unicompartmental osteoarthritis of the knee. While lateral open wedge techniques are common for valgus deformities, the data about medial open wedge techniques for varus deformities is sparse. The aim of this study was to compare the biomechanical properties of medial and lateral open wedge osteotomies using a locking Tomofix® plate (DePuy Synthes, Oberdorf, Switzerland). Our hypothesis was that there would be no difference regarding biomechanical outcome parameters between these two groups. Medial and lateral open wedge osteotomies were performed in composite bone model as routine. Each experimental group contained 6 constructs. Standardized osteotomy gaps of ten millimeters were performed and Tomofix® plates were fixed to third generation composite bones. The constructs were subsequently mounted into a servohydraulic testing machine. Axial and torsional loadings were applied as described in previous experimental studies. All specimens were subject to a load to failure mode with the mechanism of failure being noted. Both experimental groups showed comparable biomechanical properties under axial and torsional loadings. Mean high force axial stiffness was 3772 N/mm for lateral and 4185 N/mm for the medial construct. Significant differences were noted for torsional stiffness under low- (0 N) and mid-force (150 N) loadings (P = 0.002; P = 0.009), favoring the medial open wedge constructs. Medial open wedge osteotomy yields comparable biomechanical stability to the lateral open wedge procedure on the distal femur in a composite bone model.

Lateral Open Wedge Osteotomy and Lateral Condyle Fusion In Situ for Children With Condyle Nonunion and Cubitus Valgus Deformity.

Long-term nonunion of the lateral humeral condyle (LHC) can result in progressive cubitus valgus, elbow pain, instability, and delayed ulnar nerve palsy. Various techniques have been proposed for correction, each with its own advantages and disadvantages. The purpose of this study was to introduce a lateral open wedge osteotomy (LOWO) procedure combined with in situ osteosynthesis of nonunited LHC for the treatment of long-term LHC nonunion with cubitus valgus deformity. We evaluated 18 pediatric patients who had a cubitus valgus deformity greater than 10 degrees after nonunion of the LHC for more than 2 years. The LHC was fixed in situ with 1 or 2 cancellous screws, and the LOWO was fixed with a locking plate. All patients underwent clinical and radiologic evaluation, and the pre- and postoperative carrying angle (CA), range of motion (ROM), and Mayo elbow performance score (MEPS) were analyzed. Eighteen patients, with a mean age of 9.9 ± 3.9 years, underwent treatment for LHC nonunion and cubitus valgus deformity after a mean interval of 61.6 ± 24.1 months from the initial injury. The mean follow-up period was 57.6 ± 22.8 months. Union of the LHC and LOWO was achieved in all patients. The mean CA decreased significantly from 31.6 ± 4.8 degrees before surgery to 10.4 ± 2.2 degrees after surgery (P<0.001). Surgery did not decrease elbow range of motion (P=0.202). The mean MEPS increased significantly from a preoperative value of 55 ± 4.9 to a postoperative value of 91.1 ± 5.6 (P<0.001). No significant complications were observed. LOWO combined with in situ fixation of nonunited LHC is an effective approach for treating long-term LHC nonunion associated with cubitus valgus deformity.

Lateral open wedge tibial osteotomy for posttraumatic deformity

Correction of pseudoinstability and tibial malalignment by re-establishment of the pretraumatic tibial axis. Posttraumatic valgus malalignment accompanied by pseudoinstability. Infections, significant inhibition of movement and multidirectional ligament instability. Standard anterolateral approach to the proximal tibial head. Lateral open wedge high tibial osteotomy above (supra) the tibiofibular joint and opening until the pseudoinstability of the lateral collateral ligament is levelled. Partial weight bearing for 4weeks, after radiological control full body weight loading is allowed. Implant removal after full bony consolidation. There is limited evidence in the current literature but the available results show good results in 70% of the cases in long-term follow-up.

Ten-year minimal follow-up of lateral opening wedge distal femoral osteotomy for lateral femorotibial osteoarthritis: Good survivorship and high patient satisfaction.

This study aimed (1) to determine complications and survival rates of lateral opening wedge distal femoral osteotomy (LOW-DFO) in the long term, (2) to assess their clinical outcomes in the long term and (3) to identify risk factors of failure. Between 1991 and 2011, 62 LOW-DFOs were performed in the same department. Inclusion criteria were all isolated LOW-DFO performed for isolated lateral tibiofemoral osteoarthritis and valgus malalignment, with a minimum 10-year follow-up. Thirty-eight patients were included, with a mean age of 48 ± 9 years. All patients had clinical and radiological assessments. The survival curves were calculated based on the following endpoints: unicompartmental or total knee arthroplasty. The mean follow-up was 15.2 ± 4.4 [10-29] years. The mean preoperative mechanical FemoroTibial Axis (mFTA) was 188.8° ± 3.2° [184°-197°], primarily due to femur deformity (mean lateral distal femoral axis [LDFA] 83.2° ± 2.8°). Bone union was achieved in 89.5% of patients (n = 34) at a mean delay of 6.5 ± 6.7 months. The complication rate was 26% (five stiffness, one nonunion, three secondary displacements and one deep vein thrombosis). Nine revision surgeries (24%) were recorded. Survival rates at 5 and 10 years were 92.1% and 78.9%, respectively. The mean delay between DFO and total knee arthroplasty (TKA) was 11.6 ± 5.7 [1-27] years. Nineteen patients (50%) were free of TKA at the last follow-up. KSS scores were improved significantly. Return to sports was obtained in 92% of cases (n = 35), with a mean delay of 11 ± 8 months. Seventy-four per cent of patients were satisfied or very satisfied with the surgery. Eighty-four per cent would be willing to undergo the surgery again. Older age (p = 0.032) was a significant risk factor for TKA conversion. LOW-DFO is an efficient procedure to manage lateral knee osteoarthritis in young patients with valgus deformity, with a good survival rate at 10 years and high patient satisfaction. Level III.

Paper 32: Leg Length Changes Following Distal Femoral Osteotomy: Validation of a Predictive Tool and Comparison of Lateral Opening Wedge and Medial Closing Wedge Techniques

Objectives: A DFO can be performed via two techniques: a lateral opening wedge (LOW) osteotomy and a medial closing wedge (MCW) osteotomy. Small case series have looked at how leg length is affected by a lateral opening wedge DFO, however, there is a lack of research comparing these leg length changes to medial closing DFO. Additionally, no studies have presented a model for predicting the leg length changes that will occur following DFO of either technique. Given that limb length differences can lead to accelerated osteoarthritis, back pain, hip pain, and other issues, being able to predict which technique can help prevent this pathology without a secondary procedure would be an important finding. Finally, the medial closing wedge osteotomy can allow for immediate weight-bearing while the lateral opening wedge does not and typically has associated cost with bone grafting. Therefore, we designed this study to validate a tool designed to predict leg length changes after distal femoral osteotomy (DFO) and compare changes following medial closing wedge (MCW) and lateral opening wedge (LOW) techniques. Methods: A collaborative retrospective review was performed of patients from Rush and Mayo Clinic databases who received a DFO and had full-length standing radiographs both pre-and postoperatively. For each preoperative radiograph, the region on the medial (for LOW) or lateral (for MCW) distal femur cortex that would be the “hinge point” during DFO was identified. The distances from the center of the femoral head to the hinge point (“A”), from the hinge point to the center of the tibial plafond (“B”), and the resultant angle at the hinge point (“α”) were measured (Figure 1). Figure 2 demonstrates the equation used to plot a graph of the predicted leg length changes corresponding to the change in α angle produced by DFO. Final leg length was calculated on postoperative radiographs, and the difference between predicted and true leg length changes was compared using paired Wilcoxon signed rank exact tests. Results: 10 MCW and 10 LOW patients were included. For both LOW (n=10) and MCW (n=10) osteotomies, the predicted leg length change was equivalent to the true change measured on postoperative radiographs (LOW P=0.16; MCW P=0.85). LOW DFO’s had 5.10 ± 2.77 mm (range: 1.45-10.87 mm) of leg lengthening, compared to 2.61 ± 1.25 mm (range: 0.50-4.56 mm) of leg shortening (p&lt;0.001) for MCW (Figure 3). On average, there was 0.85 mm of lengthening (range 0.5-1.3 mm) for every 1° of mechanical axis correction with LOW DFO, compared to 0.45 mm of shortening (range: 0.1-1.4 mm) per 1° of MCW correction. Conclusions: This study presents a tool to accurately and reliably predict the leg length changes seen after both medial closing and lateral opening wedge DFO’s. Knowing what leg length changes to expect with each DFO technique is a useful tool that surgeons can utilize during surgical planning. Preoperative radiographic imaging can be used to predict leg length change following DFO with high reliability and accuracy. Surgeons can expect approximately 0.85mm of lengthening per 1° of DFO correction when performing LOW, compared to 0.45mm of shortening per 1° correction for MCW osteotomies.

Effect of Varus-Producing Distal Femoral Osteotomy and High Tibial Osteotomy on Compartment Pressures and Contact Area at Varying Degrees of Knee Flexion.

In patients with valgus alignment and degenerative changes in the lateral compartment, both distal femoral osteotomy (DFO) and high tibial osteotomy (HTO) can be used to unload the lateral compartment. Prior studies have shown that in valgus knees, the tibial wear is posterior and DFO exerts the greatest effect in extension; however, its effect is decreased as flexion angle rises. Medial closing-wedge (MCW) HTO would significantly decrease contact area, mean contact pressure (MCP), and peak contact pressure (PCP) in the lateral knee compartment through knee flexion to a greater extent compared with lateral opening-wedge (LOW) DFO. Controlled laboratory study. MCWHTO and LOWDFO were performed, correcting a mean of 8° of valgus alignment, in 10 cadaveric knees using plate fixation. Tibiofemoral contact pressure of the medial and lateral compartments was measured in 0°, 30°, 60°, and 90° of knee flexion before and after osteotomy using thin electronic sensors and load applied through an Instron device. PCP, MCP, and contact area were measured for each condition. The lateral MCP was significantly decreased in the HTO state compared with the native state in 30° (P = .015), 60° (P = .0199), and 90° (P < .0001) of flexion. The lateral MCP was also significantly decreased in the HTO state when compared with the DFO state in 60° (P = .0093) and 90° of flexion (P < .0001). After DFO, the lateral MCP returned to that of the native state in 60° (P > .999) and 90° (P > .999) of flexion. The lateral PCP decreased for all test states in all degrees of flexion; the HTO state was significantly decreased when compared with the native state in 60° (P < .0001) and 90° (P < .0001). With varus corrections of 8°, MCWHTO was more effective at unloading the lateral compartment than LOWDFO. This effect was significant as the knee flexion angle increased. This study should be considered as one aspect of the surgical decision-making process. In patients with mild to moderate valgus deformity without hypoplastic lateral femoral condyle and without significant joint line obliquity, MCWHTO may improve offloading of the lateral compartment in flexion.

Bilateral Distal Femoral Osteotomy for Valgus Knee Deformity May Result in Improved Patient-Reported Outcome Scores

Background: The lateral opening wedge distal femoral osteotomy (DFO) is an effective treatment for genu valgum to improve mechanical alignment, decrease lateral compartment loads, and decrease the risk of knee osteoarthritis. Multiple studies have utilized outcome scores assessing functional changes related to pain and joint stability, with a focus solely on knee pain and functional outcomes. Questions/purposes: The primary aim of this study was to evaluate patient-reported outcome measures (PROMs) that assessed knee function, pain, patient’s perception of body image, and limb deformity-related quality of life, both preoperatively and at least 1-year postoperatively. Methods: In a retrospective review of nontraumatic genu valgum patients who underwent bilateral DFO, preoperative and postoperative radiographs were evaluated. Routinely collected preoperative and 1-year postoperative PROMs scores were analyzed, using the Knee Injury and Osteoarthritis Outcome Score Jr. (KOOS-JR) and the Limb Deformity-Modified Scoliosis Research Society (LD-SRS) score, in 72 limbs (36 patients): 7 men (19.44%) and 29 women (80.56%) with an average age of 35.34 ± 13.57 years. The mean follow-up time was 36.85 ± 24.43 months. Results: Overall mechanical axis deviation, lateral distal femoral angle, and mechanical axis alignment angle were significantly improved after DFO in all patients. Both PROMs also improved significantly from preoperative to postoperative scores: LD-SRS (3.10 ± 0.56 vs 4.19 ± 0.44, respectively) and KOOS-JR (63.02 ± 19.25 vs 78.06 ± 16.29, respectively). Conclusion: This retrospective review suggests that bilateral lateral opening-wedge DFOs in patients with symptomatic valgus knee deformity may be associated with improved overall knee health, limb deformity-related quality of life, and patients’ body image. Further study is needed.

Additional Plate Fixation of Hinge Fractures After Varisation Distal Femoral Osteotomies Provides Favorable Torsional Stability: A Biomechanical Study

Background: Hinge fractures are considered risk factors for delayed or nonunion of the osteotomy gap in distal femoral osteotomies (DFOs). Limited evidence exists regarding the treatment of hinge fractures after DFO, which could improve stability and thus bone healing. Purpose: To (1) examine the effect of hinge fractures on the biomechanical properties of the bone-implant construct, (2) evaluate the biomechanical advantages of an additional fixation of a hinge fracture, and (3) test the biomechanical properties of different types of varisation DFOs. Study Design: Controlled laboratory study. Methods: A total of 32 fresh-frozen human distal femora equally underwent medial closing wedge DFO or lateral opening wedge DFO using a unilateral locking compression plate. The following conditions were serially tested: (1) preserved hinge; (2) hinge fracture along the osteotomy plane; (3) screw fixation of the hinge fracture; and (4) locking T-plate fixation of the hinge fracture. Using a servo-hydraulic materials testing machine, we subjected each construct to 15 cycles of axial compression (400 N; 20 N/s) and internal and external rotational loads (10 N·m; 0.5 N·m/s) to evaluate the stiffness. The axial and torsional hinge displacement was recorded using a 3-dimensional optical measuring system. Repeated-measures 1-way analysis of variance and post hoc Bonferroni correction were used for multiple comparisons. Statistical significance was set at P < .05. Results: Independent from the type of osteotomy, a fractured hinge significantly (P < .001) increased rotational displacement and reduced stiffness of the bone-implant construct, resulting in ≥1.92 mm increased displacement and ≥70% reduced stiffness in each rotational direction, while the axial stiffness remained unchanged. For both procedures, neither a screw nor a plate could restore intact rotational stiffness (P < .01), while only the plate was able to restore intact rotational displacement. However, the plate always performed better compared with the screw, with significantly higher and lower values for stiffness (+38% to +53%; P < .05) and displacement (–55% to −72%; P < .01), respectively, in ≥1 rotational direction. At the same time, the type of osteotomy did not significantly affect axial and torsional stability. Conclusion: Hinge fractures after medial closing wedge DFO and lateral opening wedge DFO caused decreased bone-implant construct rotational stiffness and increased fracture-site displacement. In contrast, the axial stiffness remained unchanged in the cadaveric model. Clinical Relevance: When considering an osteosynthesis of a hinge fracture in a DFO, an additional plate fixation was the construct with the highest stiffness and least displacement, which could restore intact hinge rotational displacement.

Wedgeless V-Shaped Osteotomy of the Distal Medial Femur with Locking Plate Fixation for Correction of Genu Valgum in Adolescents and Young Adults.

Genu valgum is a common disorder affecting adolescents and young adults. Treatment of this disorder requires restoration of normal mechanical axis alignment and joint orientation, for which it is important to assess whether the deformity arises from the distal femur, knee joint, or proximal tibia. Most commonly, the deformity originates from the distal femur, and various osteotomies of the distal femur have been described1-6. The presently described wedgeless V-shaped osteotomy7,8 is a good option among the various alternative procedures listed below. The anesthetized patient is placed in the supine position on a radiolucent operating table. A bolster is placed beneath the knee to relax the posterior structures. A medial longitudinal skin incision is made that extends from the level of the medial joint line to 5 cm proximal to the adductor tubercle. The vastus medialis is identified and elevated anteriorly by detaching it from its distal and posterior aspects. The leash of vessels underneath the vastus medialis is identified, and the apex of the V-shaped osteotomy is kept just proximal to it. The anterior arm of the V is kept longer than the posterior one, both of them are kept perpendicular to each other, and the apex of the V is made to point distally. The osteotomy is performed on the medial cortex with use of an oscillating saw or multiple drill holes that are then connected using a thin osteotome. Care is taken not to utilize a saw or drill on the lateral cortex. A gentle valgus thrust is applied to break the lateral cortex without periosteal disruption. The apex of the V osteotomy on the proximal fragment is trimmed, and the deformity is corrected with varus force. The osteotomy site is stabilized with use of an anatomically contoured distal medial femoral locking plate or a medial proximal tibial L-shaped buttress plate (of the contralateral side). The implant position is verified under a C-arm image intensifier. The wound is closed in layers over a suction drain in a standard manner. Various types of corrective osteotomies of the distal femur have been described in the literature, including the lateral opening wedge, medial closing wedge, dome, and spike osteotomies1-6. All of these procedures have certain limitations and shortcomings. The wedgeless V-shaped osteotomy is another described procedure that is inherently stable7,8. It is a safe procedure and yields good clinical outcomes8,9. The posterior arm of the V-shaped osteotomy is kept smaller than the anterior arm. The proximal cortical bone is allowed to dig into the cancellous bone of the wider distal metaphysis during deformity correction. Trimming the apex of proximal bone end after making the osteotomy facilitates the process. In a study of 46 patients with a mean age of 16.9 years (range, 15 years to 23 years), Gupta et al.8 reported that the mean radiographic tibiofemoral angle improved from 22.2° (range, 16° to 29°) preoperatively to 5.1° (range, 0° to 10°) postoperatively (p < 0.001). Similarly, the mean lateral distal femoral angle improved from 79.2° preoperatively to 89.1° postoperatively (p < 0.001) and the mean mechanical axis deviation improved from 19.6 mm preoperatively to 3.7 mm postoperatively (p < 0.001). A total of 44 of 46 cases had an excellent functional outcome, with the other 2 having good outcomes. None of the patients in the study had an unsatisfactory outcome. It is important to keep the whole lower limb accessible to the image intensifier intraoperatively.Identification of the leash of vessels underneath the vastus medialis is important to decide the level of the osteotomy.It is important to preserve the periosteal sleeve on the lateral aspect of the femur. CORA = center of rotation of angulationECG = electrocardiogramLDFA = lateral distal femoral angleMAD = mechanical axis deviationMPTA = medial proximal tibial angle.

TT-TG distance decreases after open wedge distal femoral varization osteotomy in patients with genu valgum & patellar instability. A pilot 3D computed tomography simulation study

BackgroundGenu valgum is considered to be a risk factor for patellar instability. Correction of valgus alone or combined with a tibial tuberosity medialization has been described. However, changes occurring in the tibial tuberosity-trochlear groove (TT-TG) distance after a lateral distal femoral opening wedge osteotomy (LDF-OWO) are not known.PurposeThis study aimed to define changes in TT-TG distance with increasing amounts of valgus correction after LDF-OWO.MethodsThree-Dimensional Computed Tomography (3D-CT) scans of six patients (two females and four males) aged between 19 and 35 years with genu valgum and patellar instability were analyzed. 3D models of femoral, tibial, and patellar bones were created with the advanced segment option of Mimics 21® software. An oblique lateral opening wedge osteotomy of the distal femur was simulated in 2-degree increments up to 12 degrees of varus opening. Change in TT-TG distance was measured in mm on 3D models of the knee.ResultsCompared to baseline without osteotomy, the TT-TG distance decreased significantly (p < 0.05) for all corrections from 2 to 12 degrees in 2° steps. The TT-TG distance decreased by an average of 1.7 mm for every 2 degrees of varus opening.ConclusionLateral opening wedge distal femoral osteotomy causes a decrease in TT-TG distance. The surgeon should be aware of the magnitude of this change (1.7 mm decrease for every 2° increment of valgus opening).

High tibial lateral closing wedge and opening wedge valgus osteotomy produce different effects on posterior tibial slope and patellar height.

To compare the clinical outcomes of performing a closed tibial high osteotomy with an open osteotomy and the changes in posterior tibia slope and patellar height. Methods were collected from three hundred and forty patients (440 knees) with high tibial osteotomy performed from January 2019 to January 2020. Forty patients (50 knees) had a lateral closed wedge tibial osteotomy (LCWHTO), and 300 patients (390 knees) had a medial open wedge tibial osteotomy (MOWHTO). The follow-up periods were 20.5 months and 19.9 months, respectively. At the final follow-up visit, both groups evaluated the Lysholm score and joint range of motion (ROM). Changes in preoperative and postoperative mechanical axis deviation (MAD), proximal medial tibial angle (MPTA), posterior tibial slope (PTS), and M-K index were compared between the two groups of patients. Lysholm scores were 79.6 ± 15.6 preoperatively and 96.0 ± 5.0 postoperatively in the LCWHTO group (p < 0.01); 83.7 ± 16.0 preoperatively and 94.3 ± 9.1 postoperatively in the MOWHTO group (p < 0.01). ROM was 136.0° ± 8.4° preoperatively and 133.2° ± 10.1° postoperatively in the LCWHTO group (p > 0.05); 136.5° ± 8.4° preoperatively and 135.7° ± 9.3° postoperatively in the MOWHTO group (p > 0.05). the MAD was (26.5 ± 4.1) mm preoperatively and 0.3 ± 2.9 mm postoperatively in the LCWHTO group (p < 0.01); 21.8 ± 6.5 mm preoperatively and -0.3 ± 2.6 mm postoperatively in the MOWHTO group (p < 0.01). The MPTA in the LCWHTO group was 75.3° ± 3.2° preoperatively and 89.5° ± 2.4° postoperatively (p < 0.01). 77.1° ± 3.0° preoperatively and 90.6° ± 2.7° postoperatively in the MOWHTO group (p < 0.01). M-K index was 0.78 ± 0.08 preoperatively and 0.79 ± 0.07 postoperatively in the LCWHTO group (p > 0.05). 0.78 ± 0.05 before and 0.75 ± 0.05 after surgery in the MOWHTO. 10.8° ± 3.0° PTS before and 8.1° ± 3.4° after surgery in the LCWHTO group (p < 0.05); 10.2° ± 3.1° preoperatively and 10.9° ± 4.0° postoperatively (p > 0.05). LCWHTO decreases the PTS and has no effect on patellar height; MOWHTO does not affect the PTS but decreases patellar height. The patient should individualize the choice of the osteotomy.

Paper 23: Taking the Load Off: Effect of Varus Producing Distal Femoral Osteotomy and High Tibial Osteotomy on Compartment Pressures and Contact Area in Varying Stages of Knee Flexion

Objectives: Study Objective: Evaluate mean contact area, mean contact pressure, and peak contact pressure in the medial and lateral compartment of the knee following varus producing high tibial osteotomy and distal femoral osteotomy in varying states of knee flexion (0*, 30*, 60*, 90*). Background: Genu valgum causes mechanical pressure to be transferred to the lateral compartment. In patients with valgus alignment and a diseased lateral compartment, both lateral opening wedge distal femoral osteotomy (DFO) and high tibial closing wedge osteotomy (HTO) can be used to unload a diseased lateral compartment of the knee. To the best of our knowledge, there are no biomechanical studies investigating how a DFO and HTO affect lateral compartment contact pressure and area in varying states of flexion. Prior anatomic studies have shown that, in valgus knees, the tibial wear is posterior. Additional, biomechanical studies have indicated that DFO exerts the greatest effect in full extension but it’s effect is decreased as flexion angle rises. Hypothesis: Medial closing wedge high tibial osteotomy will significantly decrease contact area, mean contact pressure and peak contact pressure in the lateral knee compartment through knee flexion to a greater extent compared to lateral opening wedge distal femoral osteotomy. Methods: Lateral opening wedge DFO and medial closing wedge HTO was performed, correcting a mean of 8°, in 10 cadaveric knees using plate fixation. Tibio- femoral contact pressure of the medial and lateral compartment was measured in 0°, 30°, 60°, and 90° of knee flexion before and after osteotomy using thin electronic sensors (K-scan Model 4000, 1500 psi; Tekscan Inc, South Boston, MA) and load applied through an Instron device (Instron, Norwood, MA). Peak contact pressure (PCP), average contact pressure (ACP), and contact area (CA) were measured for each condition. Mixed-effects regression analyses were used to compare the change in variables before and after osteotomy and between flexion angles. Results: The lateral ACP was significantly decreased in the HTO state when compared to native in 30° (p=0.015), 60° (p=0.0199), and 90° (p&lt;0.0001) of flexion. The lateral ACP was also significantly decreased in the HTO state when compared to the DFO state in 60° (p=0.0093) and 90° of flexion (p&lt;0.0001). Following DFO, the lateral ACP returned to that of the native state in 60° (p=1.000) and 90° (p=1.000) of flexion. The medial ACP was significantly increased when compared to both the native and HTO state in 60° (p&lt;0.001; p=0.015) and 90° (p&lt;0.0001; p=0.0435) of flexion. Conclusions: With varus corrections of &lt;10°, medial closing HTO is more effective at unloading the lateral compartment than lateral opening DFO. This effect is amplified as the knee flexion angle increases.

Lateral Opening Wedge Distal Femur Osteotomy and Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Instability

Background: A uniplanar, varus-producing distal femur osteotomy (DFO) may improve patellar tracking by effectively medializing the tibial tubercle, decreasing the Q-angle, and reducing the dislocation vector on the patella. Indications: A 17-year-old female with 8° of genu valgum presented with 18 months of symptomatic left knee patellar instability episodes that limit her function. Technique Description: A lateral subvastus approach to the distal femur was performed. Medial patellofemoral ligament reconstruction (MPFL-R) was conducted up to the point of femoral-sided graft fixation. A lateral opening wedge DFO was made with a sagittal saw and osteotomes, with care taken to maintain the medial cortical hinge. After distraction of the osteotomy site and femoral head allograft wedge placement, the osteotomy was secured with a lateral distal femoral locking plate. Finally, femoral-sided graft fixation for the MPFL-R was completed. Results: There were no immediate complications after surgery. Surgical management led to improvement of the patient's patellar instability, which allowed return to the prior baseline level of function. Discussion/Conclusion: The senior author's preferred technique for a lateral opening wedge DFO in association with an MPFL-R is presented. A varus-producing DFO is a surgical option for patients with genu valgum and recurrent patellar instability who have failed conservative management. This case demonstrates the efficacy of a lateral opening wedge DFO in improving patellar tracking and improving knee function by resolving recurrent patellar instability episodes. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Finite element analysis of medial closing and lateral opening wedge osteotomies of the distal femur in relation to hinge fractures

PurposeIntraoperative hinge fractures in distal femur osteotomies represent a risk factor for loss of alignment and non-union. Using finite element analysis, the goal of this study was to investigate the influence of different hinge widths and osteotomy corrections on hinge fractures in medial closed-wedge and lateral open-wedge distal femur osteotomies.MethodsThe hinge was located at the proximal margin of adductor tubercle for biplanar lateral open-wedge and at the upper border of the lateral femoral condyle for biplanar medial closed-wedge distal femur osteotomies, corresponding to optimal hinge positions described in literature. Different hinge widths (5, 7.5, 10 mm) were created and the osteotomy correction was opened/closed by 5, 7.5 and 10 mm. Tensile and compressive strain of the hinge was determined in a finite element analysis and compared to the ultimate strain of cortical bone to assess the hinge fracture risk.ResultsDoubling the correction from 5 to 10 mm increased mean tensile and compressive strain by 50% for lateral open-wedge and 48% for medial closed-wedge osteotomies. A hinge width of 10 mm versus 5 mm showed increased strain in the hinge region of 61% for lateral open-wedge and 32% for medial closed-wedge osteotomies. Medial closed-wedge recorded a higher fracture risk compared to lateral open-wedge osteotomies due to a larger hinge cross-section area (60–67%) for all tested configurations. In case of a 5 mm hinge, medial closed-wedge recorded 71% higher strain in the hinge region compared to lateral open-wedge osteotomies.ConclusionDue to morphological features of the medial femoral condyle, finite element analysis suggests that lateral-open wedge osteotomies are the preferable option if larger corrections are intended, as a thicker hinge can remain without an increased hinge fracture risk.

Poster 216: The Effects of Lateral Opening Wedge Distal Femoral Osteotomy on Meniscus Allograft Transplantation: A Biomechanical Evaluation

Objectives:Lateral meniscus deficiency with valgus malalignment increases the risk and rate of lateral compartment osteoarthritis. Lateral meniscus allograft transplantation (LMAT) with concomitant varus-producing lateral opening wedge distal femoral osteotomy (LOWDFO) is an available option to treat this pathology. No biomechanical data currently exists evaluating the effect on joint forces with these combined procedures. The purpose of this study is to evaluate the effects of LMAT with concomitant varus-producing LOWDFO on lateral and medial compartment biomechanics. We hypothesize that LMAT restores lateral compartment biomechanics back to native intact forces, varus-producing LOWDFO improves lateral compartment forces following LMAT, and medial compartment forces change to a lesser degree in response to mechanical varus.Methods:Ten human cadaveric knees underwent varus-producing LOWDFO and were placed in an external fixator. Anatomic alignment was standardized for each knee and utilized as a proxy for mechanical alignment. Thin film Tekscan pressure sensors were placed sub-meniscal and specimens were loaded on a biaxial dynamic testing machine to 800N within a custom designed apparatus, with loading angles between 9° valgus and 6° varus of mechanical alignment. Testing conditions included the intact meniscus, lateral meniscus deficiency, and LMAT. Statistical analysis was performed by creating two-factor random-intercepts linear mixed-effects models to compare peak pressure and contact area among the three experimental meniscus conditions.Results:Isolated varus-producing LOWDFO to 6° varus in the setting of meniscus deficiency was unable to restore joint forces to the level of the intact meniscus in neutral alignment (Mean Contact Pressure: 175%, Peak Pressure 135%, Contact Area -41%, P>0.05). LMAT restored mean contact and peak pressures, with no significant differences compared to the intact meniscus (P<0.05). LMAT resulted in significantly lower contact areas from 9° valgus to 0° (P>0.05), but this was restored to intact state at 3° and 6° varus (P<0.05). Within the lateral compartment following LMAT, every additional 1° of DFO correction contributes to a decreased in mean contact pressure of 5.6% (-0.0479 N/mm2)(Figure 1), a decrease in peak pressure of 5.9% (-0.154 N/mm2)(Figure 2), and a decrease in contact area of 1.4% (6.99 mm2)(Figure 3), as compared to forces in neutral alignment. Within the medial compartment following LMAT, every additional 1° of DFO correction contributes to an increase in mean contact pressure of 7.3% (+0.034 N/mm2), an increase in peak pressure of 12.6% (+0.160 N/mm2), and an increase in contact area of 4.3% (20.53 mm2), as compared to forces in neutral alignment. However, baseline forces in the medial compartment are significantly lower at baseline compared to lateral compartment forces (P>0.05).Conclusions:This is the first biomechanical study evaluating the effects of concomitant LMAT and varus-producing LOWDFO. Isolated varus-producing LOWDFO is inadequate to restore forces in the meniscus deficient knee. LMAT restores near normal forces, and concomitant LOWDFO improves the lateral compartment biomechanical profile. Although to a smaller magnitude, force changes in the medial compartment are significant with varus-producing LOWDFO. Unloading to 0° following LMAT may be ideal. Overall, this study provides tools to for the surgeon to individualize alignment correction for each patient to optimize outcomes.Figure 1.Mean Contact PressureFigure 2.Peak Contact PressureFigure 3.Contact Area

Osteochondral Allograft Transplantation of the Lateral Femoral Condyle and Distal Femoral Osteotomy in the Setting of Failed Osteochondritis Dissecans Fixation

Osteochondritis dissecans (OCD) is a pathologic condition, most commonly affecting the knee joint in adolescents and young adults, although pathology can also be found at the elbow and ankle. Lesions to the medial femoral condyle are classically associated with varus alignment, while lesions to the lateral femoral condyle are seen in patients with valgus malalignment. Common risk factors for failed fixation of OCD lesions include unstable lesions to the lateral femoral condyle, screw breakage, older age, and closed physes. The purpose of this technical note is to describe the preoperative planning and step-by-step surgical approach for treatment of failed fixation of an OCD lesion of the posterior aspect of the lateral femoral condyle in young, active patients using an osteochondral allograft, a lateral opening wedge distal femoral osteotomy to correct malalignment, and a tibial tubercle osteotomy to facilitate access to the lesion.

Basics of Coronal Plane Deformity Correction

High tibial osteotomy (HTO) and distal femoral osteotomy (DFO) are utilized to correct knee malalignment in patients with coronal plane deformities. Identifying the deformity of the lower extremity using a standardized, reproducible approach is critical prior to correction of lower limb malalignment with an osteotomy procedure. Appropriate radiographs, including bilateral long-leg standing films, are critical to measure the anatomical and/or mechanical axes and calculate the required degree of correction. The femoral and tibial mechanical axes, malalignment (varus or valgus), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA) should be measured during coronal plane deformity analysis and accounted for during surgical planning. This paper focuses on the surgical technique for medial opening and lateral closing wedge HTO, as well as medial closing and lateral opening wedge DFO.

Flexion Dislocation After Limb Lengthening: Correction With Distal Femoral Osteotomy, Quadriceps Release, and Physeal-Sparing Medial Patellofemoral Ligament (MPFL) Reconstruction

Background: Patellar instability is a common clinical condition in skeletally immature individuals. Surgical treatment is considered when risk of recurrence is high. Indications: Distal femoral osteotomy is indicated in the setting of obligate flexion dislocation where femoral valgus contributes to a shortened lateral column, with concurrent quadriceps procedures considered for chronic contracture and medial patellofemoral ligament (MPFL) reconstruction for added stabilization. Technique Description: This procedure is performed in a stepwise manner as some components may not be necessary based on the patient’s specific anatomy. The procedure begins with a lateral iliotibial (IT) band soft tissue release or lengthening if possible. The distal femoral osteotomy is then performed utilizing a lateral opening wedge technique. Bone graft is placed in a structural fashion to maintain the correction while a locking plate is inserted. In patients with chronic lateral patellar dislocation, correction of bony alignment may not completely restore tracking. If lateral maltracking persists after further distal soft tissue release, a VY-lengthening quadricepsplasty can be considered. To perform this, the vastus lateralis (VL) is first released. In this patient, the patella was able to be stabilized centrally after VL release, and therefore, the VY-plasty was not performed. The soft tissue attachments for the final MPFL reconstruction are then prepared, including two at the superomedial and midbody of the patella and one at the adductor tendon. The whip-stitched graft is then passed through the adductor sling followed by the patellar periosteal tunnels with the knee in slight flexion to ensure centralization within the trochlear groove. Examination under anesthesia before final fixation of the reconstruction should demonstrate 1A lateral translation. Results: Correction of distal femoral valgus with osteotomy, in isolation or in combination with other patellar stabilizing procedures, has demonstrated significant improvement in patient-reported outcomes and reduced redislocation rates. However, large cohort studies are limited. Discussion/Conclusion: Both osseous and soft tissue abnormalities are important to consider in since they can contribute in varying degrees to patellar maltracking. Therefore, assessment of patellar tracking should be performed frequently to guide extent of surgical correction necessary.

Research progress of osteotomy around knee in the treatment of valgus knee osteoarthritis

To review the research progress of surgical methods of osteotomy around the knee in the treatment of valgus knee osteoarthritis. The relevant literature on the surgical treatment of valgus knee osteoarthritis at home and abroad in recent years was reviewed, and the advantages, disadvantages, and effectiveness of different surgical methods of osteotomy around the knee were summarized. For young and active patients with symptomatic valgus knee osteoarthritis, osteotomy around the knee is a safe and reliable treatment option. At present, the main surgical methods include medial closing wedge distal femoral osteotomy, lateral opening wedge distal femoral osteotomy, medial closing wedge high tibial osteotomy, and lateral opening wedge high tibial osteotomy. The indications, advantages, and disadvantages of different osteotomies are different, and the selection of appropriate surgical method is the key to achieve good effectiveness. There are many osteotomies in the treatment of valgus knee osteoarthritis. In order to achieve good results, improve survival rate, and reduce postoperative complications, the most reasonable surgical strategy needs to be developed according to different situations.

Lateral open wedge calcaneus osteotomy with bony allograft augmentation in adult acquired flatfoot deformity. Clinical and radiological results

The aim of this study is to evaluate the results of patients underwent lateral open wedge calcaneus osteotomy with bony allograft augmentation combined with tibialis posterior and tibialis anterior tenodesis. Twenty-two patients underwent adult-acquired flatfoot deformity were retrospectively evaluated with a minimum 2-year follow-up. Radiographic preoperative and final comparison of tibio-calcaneal angle, talo–first metatarsal and calcaneal pitch angles have been performed. The Visual Analog Scale, American Orthopedic Foot and Ankle Score, the Foot and Ankle Disability Index and the Foot and Ankle Ability Measure were used for subjective and functional assessment. The instrumental range of motion has been also assessed at latest follow-up evaluation and compared with preoperative value. There was a significant improvement of final mean values of clinical scores (p < 0.001). Nineteen out of 22 (86.4%) patients resulted very satisfied or satisfied for the clinical result. There was a significant improvement of the radiographic parameters (p < 0.001). There were no differences between preoperative and final values of range of motion. One failure occurred 7 years after surgery. Adult-acquired flatfoot deformity correction demonstrated good mid-term results and low recurrence and complications rate.Level of evidenceLevel 4, retrospective case series.