Early complications of medial opening wedge high tibial osteotomy using autologous tricortical iliac bone graft and T-plate fixation

Gap Volume Based on Computed Tomography Measurement Is a Strong Risk Factor for Delayed Gap Healing After Open-Wedge High Tibial Osteotomy

PURPOSE

To identify factors that affect delayed gap healing after open-wedge high tibial osteotomy (OWHTO) and to determine whether large gap volume is a predictor of delayed gap healing.

METHODS

This retrospective study analyzed biplane OWHTO performed between 2019 and 2023 for knee osteoarthritis or osteonecrosis. The minimum follow-up period was 1 year. Delayed gap healing was defined when the medial half of the osteotomy gap area had not reached the consolidation phase by 6 months after surgery based on anteroposterior knee radiographs. Gap volume was calculated from computed tomography images. Logistic regression was performed using body height, smoking, correction angle, hinge fracture, flange thickness, and gap volume. A gap volume cutoff value for delayed gap healing was determined with receiver operating characteristic curve analysis. Gap volume was predicted with multiple linear regression.

RESULTS

There were 80 knees in 71 patients (36 men and 44 women). The mean gap volume was 7.6 cm3. Gap healing rates at 3, 6, 9, and 12 months after surgery were 26%, 65%, 89%, and 100%, respectively. There were 25 knees with delayed gap healing. Male sex was not a significant risk factor when adjusted for body height. Multivariate logistic regression revealed that only larger gap volume was a significant risk factor (odds ratio, 1.45; P = .006). The gap volume cutoff value was 7.6 cm3, with an area under the curve of 0.74. Tall body height and a large correction angle (both P < .001) were associated with a significantly larger gap volume (R2 = 0.73).

CONCLUSIONS

Large gap volume is the most important risk factor for delayed gap healing after OWHTO. Gap volume can be predicted based on body height and correction angle. When OWHTO with substantial correction is planned for tall men, surgeons should be aware of possibly delayed gap healing.

LEVEL OF EVIDENCE

Level IV, retrospective case-control study.

Infection in osteotomy around the knee: Incidence, management and outcomes in a high-volume case series

PURPOSE

Current evidence around the management of osteotomy-related infection is insufficient to robustly underpin the expert statements formulated by a recent European consensus statement. We present a review of a large case series in a high-volume osteotomy practice to contribute to the understanding of the incidence, management and outcome of infection in this subspecialty area.

METHODS

Analyses of two prospectively collected databases for all osteotomy around the knee and infections related to osteotomy were performed, along with a review of hospital readmission data to capture all osteotomy-related infections. Clinical notes were reviewed to assess patient demographics, incidence of infection, how infection was managed and clinical outcome.

RESULTS

In a series of 822 osteotomies in 755 patients, there were 21 (2.8%) cases of suspected infection. Twelve (1.6%) were contemporaneously deemed 'superficial' and nine confirmed 'deep' infections (1.2%). Deep infections were all successfully managed with wound debridement, with or without plate removal, depending on union and time from initial surgery. One of these infections was noted during a revision procedure, but no revision was carried out as a direct result of infection, no external fixation was required and no infected nonunions were experienced.

CONCLUSION

All of the cases in this series were managed successfully with debridement ± removal of the plate, without the need for revision or external fixation. Any potential signs of infection around an osteotomy, especially in the case of medial high tibial osteotomy, should raise awareness for deep infection and the need for further surgery due to the limited overlying soft tissue cover. This evidence supports the recent European Society of Sports Traumatology, Knee Surgery and Arthroscopy algorithm.

LEVEL OF EVIDENCE

Level IV, case series.

Use of Tibial Cortical Autograft for the Osteotomy Site in Medial Opening-Wedge High Tibial Osteotomy

Background

Medial opening-wedge high tibial osteotomy (OWHTO) is a useful treatment option in patients with medial compartment osteoarthritis. Typically, the osteotomy site is filled with material such as autologous bone graft, allograft, or synthetic bone substitute. However, all these options have disadvantages.

Purpose/Hypothesis

The purpose of this study was to describe tibial cortical autograft as an alternative to conventional graft options. It was hypothesized that the tibial rectangular cortical bone that is removed from the proximal medial cortical surface of the distal tibial fragment longitudinally could be a reliable option for recovery of the gap in the osteotomy area.

Study Design

Cohort study; Level of evidence, 3.

Methods

A total of 520 patients with medial compartment osteoarthritis who underwent OWHTO between June 2009 and March 2019 were retrospectively analyzed. Patients were divided into 3 groups according to the graft material used to fill the osteotomy site: allograft in group A, iliac crest autograft in group B, and tibial autograft in group C. Bone union, evaluated by radiographs performed at 2 weeks, 4 weeks, 2 months, 3 months, 6 months, and 1 year postoperatively, was defined as occurring when at least 50% of the gap site was bridged with callus. Clinical assessment was performed using the International Knee Documentation Committee (IKDC) and Lysholm scores.

Results

Included were 122 patients: 40 patients in group A, 42 patients in group B, and 40 patients in group C. The mean correction was 13.87°± 3.58° in group A, 12.33°± 3.92° in group B, and 14.10°± 2.99° in group C. The mean time for radiological bone union was 6.95 ± 1.40 months in group A, 4.48 ± 1.02 months in group B, and 5.07 ± 1.70 months in group C. Patients in all groups had similar IKDC and Lysholm scores at the final follow-up.

Conclusion

This is the first report of this specific procedure in the literature. All clinical and radiological findings showed that use of tibial cortical autograft was an efficient method in patients undergoing OWHTO.

Incidence of Complications and Revision Surgery After High Tibial Osteotomy: A Systematic Review

BACKGROUND

High tibial osteotomy (HTO) is a well-recognized procedure for its effectiveness in treating symptomatic early knee arthritis and malalignment. Although there are numerous systematic reviews evaluating the management and outcomes after HTO, there are few investigations on complications of this procedure.

PURPOSE

To systematically review the literature to determine the incidence of intraoperative and postoperative complications associated with medial opening wedge and lateral closing wedge HTOs.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

The Cochrane Database of Systematic Reviews, PubMed, Embase, and MEDLINE databases were queried for studies reporting complications associated with HTO with or without concomitant procedures. Data including patient characteristics, procedure type, concomitant procedures, follow-up time, and postoperative imaging were extracted. Rates of intra- and postoperative complications, reoperations, and conversion to arthroplasty were recorded.

RESULTS

A total of 71 studies were included for analysis, comprising 7836 patients. The overall intraoperative complication rate during HTO was 5.5% (range, 0%-29.3%), and the overall postoperative complication rate was 6.9% (range, 0%-26.6%). The most common intraoperative complication was lateral hinge fracture (incidence, 9.1%; range, 0%-30.4%) in medially based HTOs and peroneal nerve injury in laterally based HTOs (incidence, 3.2%; range, 0%-8.7%). The overall incidence of neurovascular injury after medially or laterally based HTOs was 1.1% (range, 0%-18.9%). The most common postoperative complication was superficial infection (incidence, 2.2%; range, 0%-13%). Of the included studies, 62 included postoperative radiographic analysis, and among those, the incidence of nonunion was 1.9% (range, 0%-15.5%), loss of correction was 1.2% (range, 0%-34.3%), and implant failure was 1.0% (range, 0%-10.2%). Among studies reporting revision surgeries, the overall reoperation rate was 15.5% (range, 0%-70.7%), with the most common type of reoperation being hardware removal (incidence, 10.0%; range, 0%-60%).

CONCLUSION

Intraoperatively, medially based HTOs are associated with a 1 in 11 risk of lateral hinge fracture and laterally based HTOs with a 1 in 30 risk of peroneal nerve injury. Postoperative complication rates in the range of 10% to 15% can be expected, including infection (2.9%), loss of correction (1.2%), and nonunion (1.9%). Patients should also be counseled that the reoperation rate is approximately 15%, with hardware removal being the most common procedure.

A systematic approach to managing complications after proximal tibial osteotomies of the knee

Proximal tibial osteotomy (PTO) is an effective procedure for active and young adult patients with symptomatic unicompartmental osteoarthritis and malalignment. They were considered technically demanding and prone to various complications related to the surgical technique, biomechanical or biological origin. Among the most important are hinge fractures and delayed or non-healing, neurovascular complications, loss of correction, implant-related problems, patellofemoral complaints, biological complications and changes in limb length. Being aware of these problems can help minimizing their prevalence and improve the results of the procedure.The aim of this narrative review is to discuss the potential complications that may occur during and after proximal tibial osteotomies, their origin and ways to prevent them.

Analysis of popliteal artery location for high tibial and distal tuberosity osteotomy using contrast-enhanced computed tomography

Background

Our objective was to evaluate the location of popliteal artery (PA) in osteotomy planes during high tibial osteotomy (HTO) and to determine a safer angle for screw drilling to the tibial tuberosity during distal tuberosity osteotomy (DTO).

Methods

Twenty knees in 20 patients who underwent contrast-enhanced computed tomography for cardiovascular diseases were examined. Osteotomy planes for open-wedge HTO (OWHTO) and hybrid closed-wedge HTO (hybrid CWHTO) were created using three-dimensional bone models. The distance from the posterior cortex of the tibia to the PA (dPC-PA) in the osteotomy planes was measured in the virtual osteotomy planes. The dangerous point (Point D1) was defined as the point 17.5 mm away from PA, setting the working length of the bone saw as 35 mm. The distance between the most medial point of the tibial cortex (Point M) and Point D1 in OWHTO and the most lateral point (Point L) and Point D1 in hybrid CWHTO were examined (dM-D1 and dL-D1, respectively). The location of Point D1 to the osteotomy line (%D1) was expressed as percentage, setting the start and end of the osteotomy line as 0% and 100%, respectively. To determine the safe angle for screw drilling in DTO, the angle between the line tangential to the medial cortex of the tibia and that passing through the center of the tibial tuberosity and PA were measured.

Results

In OWHTO and hybrid CWHTO, the mean dPC-PA was 10.6 mm (6.9–16.5 mm) and 10.2 mm (7.3–15.4 mm), respectively. The mean dM-D1 in OWHTO was 25.9 mm (24.6–27.2 mm) and dL-D1 in hybrid CWHTO was 5.1 mm (2.9–7.4 mm). The mean %D1 was 47.6 ± 3.7% in OWHTO and 9.3 ± 4.1% in hybrid CWHTO, respectively. The minimal angle between the two lines in DTO was 35.2°.

Conclusion

PAs could run within 10 mm from the posterior cortex in the osteotomy planes of HTO. Therefore, proper posterior protection is necessary when cutting posterior cortex. An angle of less than 35° against the medial cortex line would be safe for screw fixation to avoid vascular injury in DTO.

The effect of the distance between the end point of the osteotomy and the lateral cortex on the lateral cortical hinge fracture in medial opening-wedge high tibial osteotomy

Background The purpose of this study was to compare the effects of different distances between the end point of the osteotomy and the lateral cortex on the risk of lateral cortical fracture in the medial opening-wedge high tibial osteotomy (MOWHTO) procedure. Methods Eighteen synthetic tibia models were used. Saw cuts were performed on the test models (n=6 for all groups). Wedge gap distance and wedge opening load were evaluated using compression tests. Findings The mean maximum gap distance without a lateral cortical fracture was 19.90 mm in Group 5, 15.49 mm in Group 10, and 11.23 mm in Group 15. The differences between Group 5 and Group 10, Group 5 and Group 15, and Group 10 and Group 15 were statistically significant. The mean load just before the fracture was 13.24 N in Group 5, 18.31 N in Group 10, and 26.16 N in Group 15. The difference between Group 5 and Group 15 was statistically significant. No significant difference was observed between Group 10 and both Group 5 and Group 15. Interpretation As the end point of the osteotomy is brought gradually closer to the lateral cortex, wider gaps can be opened without a lateral cortical fracture. Thus, higher angle corrections can be achieved more safely by bringing the end point of the osteotomy closer to the lateral cortex, which should be preferred to reduce the risk of a lateral cortical hinge fracture during the MOWHTO procedure, from a clinical viewpoint.

A Computer-Assisted Approach Regarding the Optimization of the Geometrical Planning of Medial Opening Wedge High Tibial Osteotomy

Opening wedge high tibial osteotomy (OWHTO) is a surgical procedure often used to eliminate the effects of knee osteoarthritis, a disease that is becoming more widespread worldwide. Optimizing the geometric planning of this operation is a very important preparatory step for the success of the intervention and rapid postoperative recovery. This optimization is performed in two main directions. The first direction evaluates the intraoperative behavior of the tibia during the osteotomy by optimizing four geometric parameters that characterize geometric planning. The second direction aims at a postoperative evaluation of the flat tibia-osteosynthesis assembly taking into account the optimal position on the medial–lateral articular line through which the corrected mechanical axis of the tongue passes and implicitly offloads the transfer from the medial area to the side of the knee. The research methods used are exclusively computer-assisted such as: computer-aided design (hereinafter CAD) for geometric modeling of the tibia taking into account the real bone structure, the finite element method (hereinafter FEM) for performing numerical analyses and design of the experiment (hereinafter DOE) for the design of the research. The results obtained are eloquent and clearly presented and can be important elements for orthopedic doctors at the geometric planning stage of the OWHTO.

Tibial cancellous bone auto-grafting for medial open-wedge high tibial osteotomy: bone void filling with tissue harvested from osteotomized medullary canal

The aim of the study was to evaluate the clinical and radiological outcomes in a series of patients undergoing open wedge high tibial osteotomy (OWHTO) using tibial cancellous autograft harvested from the osteotomized medullary canal which is not reported in the literature before. Patients with medial compartment osteoarthritis were treated with OWHTO and tibial cancellous auto- grafting performed from the osteotomized medullary canal and used for bone void filling. Seventy patients (seventy-two knees) treated with OWHTO were analyzed. All patients started partial weight-bearing with crutches the day after surgery and full-weight bearing eight weeks after surgery, according to radiological evaluation. Fifty-seven women and 13 men with a mean age of 54.2±8.1 years were evaluated in this study. The mean correction angle was 8.4±2.5° (range: 5.3°-14.3°). The osteotomy sites of all patients were grafted with tibial cancellous autografts. In all patients bony union was detected after surgery. No implant failures or major complications were en- countered. Clinical and radiological findings revealed that bone void filling with the harvested autograft from the osteotomized medullary canal may be a satisfactory and reliable option in OWHTO.

Comparative Analysis of Serial Union Patterns After Opening-Wedge High Tibial Osteotomy with and without Bone-Void Fillers

BACKGROUND

Opening-wedge high tibial osteotomy produces opening gaps; however, there is little consensus on bone graft necessity and the material that would produce a superior union. The purposes of the present study were (1) to compare the serial union patterns associated with various bone-void fillers, (2) to determine whether bone-void filler is necessary to achieve bone union of the opening gap, and (3) to determine whether bone union is different according to the correction degree during opening-wedge high tibial osteotomy.

METHODS

In this retrospective study, 97 knees were randomly assigned to treatment with hydroxyapatite chip bone (Group A), allogenic chip bone (Group B), or no bone graft (Group C) and were analyzed after a minimum 1-year follow-up. To compare the bone union pattern, the area of callus filling located at the most medial side on an anteroposterior radiograph of the knee was recorded, and a modified van Hemert scoring system was used in the mediolaterally divided 5 zones. The correlations between the correction degree and bone union scores were evaluated.

RESULTS

There were no significant differences in the extent of mediolateral bone-healing at 6 weeks or 3 months postoperatively (p = 0.172 and p = 0.228). However, Group C showed more prominent progression of the gap filling to the medial side compared with Groups A and B at 6 months postoperatively (p = 0.002). Group C showed slow progression of bone union up to 6 weeks but surpassed the other groups at 6 months. The union pattern was not different between Groups A and B, and the correction degree was not correlated with bone union beyond 3 months postoperatively.

CONCLUSIONS

Despite the different gap-healing patterns, opening-wedge high tibial osteotomy without bone graft achieved bone union comparable with allogenic and synthetic graft materials. Group C (no bone graft) showed slower progression of bone union but surpassed the other groups at around 6 months. Based on the union pattern, there was no difference depending on the correction degree and the use of bone-void fillers.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Risk Factor Analysis for Infection after Medial Open Wedge High Tibial Osteotomy

Background: Medial open wedge high tibial osteotomy (MOWHTO) is a well-established treatment for osteoarthritis of the medial tibiofemoral compartment. Surgical site infection (SSI) after MOWHTO is a devastating complication that may require further surgery. In this study, we aimed to identify the risk factors for infection after MOWHTO over 1 to 4 years of follow-up. Methods: Fifty-nine patients who underwent MOWHTO combined with knee arthroscopic surgery were included in this prospective study. Artificial bone grafts were used in all cases. Possible risk factors, including sex, age, body mass index (BMI), underlying disease, hospitalization length, correction angle, and surgery time, were recorded. Both univariate and multivariate analysis were used. Results: A total of 59 patients who underwent 61 operations were included. Eleven patients (18.0%) were reported to have SSI. Univariate analysis showed that smoking and diabetes mellitus were positively associated with SSI. Multivariate analysis showed that smoking and age were positively associated with SSI. Three patients (4.9%) were reported to suffer from deep SSI, requiring surgical debridement, all of whom were male smokers. Conclusion: Smoking, diabetes mellitus, and old age were identified to be possible risk factors of SSI after MOWHTO. These findings are common risk factors of SSI after orthopedic surgery according to the literature. Patient selection should be performed cautiously, and postoperative prognosis for MOWHTO should be carefully explained to patients who smoke.

A supplemental screw enhances the biomechanical stability in medial open-wedge high tibial osteotomy

Background

The supplemental screw technique was introduced for salvage of lateral hinge fracture in medial open-wedge high tibial osteotomy (owHTO). The efficacy of its use in protection of lateral hinge fracture and corresponding biomechanical behaviors remained unclear. The current study was aimed to clarify if a supplemental screw can provide better protection to lateral hinge in biomechanical perspective.

Materials

An in vitro biomechanical test was conducted. Tibial sawbones, commercial owHTO plates and a cannulated screw were utilized for preparing the intact, owHTO, and owHTO with cannulated screw insertion specimens. A “staircase” dynamic load protocol was adopted for axial compressive test with increasing load levels to determine structural strength and durability by using a material testing system, while a motion capture system was applied for determining the dynamic changes in varus angle and posterior slope of the tibia plateau with various specimen preparation conditions.

Results

Type II lateral hinge fracture were the major failure pattern in all specimens prepared with owHTO. The insertion of a supplemental cannulated screw in medial owHTO specimens reinforced structural stability and durability in dynamic cyclic loading tests: the compressive stiffness increased to 58.9–62.2% of an intact specimen, whereas the owHTO specimens provided only 23.7–29.2% of stiffness of an intact specimen. In view of tibial plateau alignment, the insertion of a supplemental screw improved the structural deficiency caused by owHTO, and reduced the posterior slope increase and excessive varus deformity by 81.8% and 83.2%, respectively.

Conclusion

The current study revealed that supplemental screw insertion is a simple and effective technique to improve the structural stability and durability in medial owHTO.

Complications, Additional Surgery, and Joint Survival Analysis After Medial Open-Wedge High Tibial Osteotomy

The reported incidence of complications following medial open-wedge high tibial osteotomy (MOWHTO) varies. The authors sought to assess the complications, additional surgeries, and joint survival following MOWHTO in patients with isolated medial compartment arthrosis during a mean follow-up of 10 years. This retrospective study involved patients implanted with spacer plates, angle adjustable plates, or inverse L-type plates with wedges between 2000 and 2010. A total of 504 knees from 441 patients were examined. Mean age of the study population was 52.6±7.0 years, with 56 (11.1%) knees from men and 448 (88.9%) from women. The 10-year Kaplan-Meier joint survival rate was 94.8%. Overall complication rate for MOWHTO was 63.7%, with complications in 20.3% of treated knees requiring additional surgery. In this population, although the overall complication rate and the need for additional surgery were high, the need for additional surgery resulting from serious complications was low (2.6%). The high joint survival rate and low rate of additional surgery for serious complications indicate that MOWHTO can be safely applied in patients with isolated medial gonarthrosis. [Orthopedics. 2020;43(5):303-314.].

The outcome of biphasic calcium phosphate bone substitute in a medial opening wedge high tibial osteotomy

BACKGROUND

Our objective was to assess clinical and radiological findings following a medial opening wedge high tibial osteotomy using a biphasic calcium phosphate (BCP) synthetic bone substitute, designed as a wedge with two differing zones of density. The in-vivo behaviour of this type of bone substitute over time is currently unknown.

HYPOTHESIS

Our hypothesis was that BCP synthetic bone would facilitate bone union and undergo replacement with host bone over the study period.

PATIENTS AND METHODS

Fifteen sequential patients were followed prospectively for minimum 4-years post-operatively. All patients were evaluated clinically using patient reported outcome measures and radiologically to evaluate alignment with maintenance of the osteotomy correction, and bone union with expected BCP dissolution.

RESULTS

All patients had good clinical scores with no reported complications at 4 years. In all cases there were radiographic findings of bone union with consolidation and no loss of correction. However the graft remained densely radiopaque at final follow-up.

DISCUSSIONS

This study demonstrates that a BCP graft in combination with a locking plate for a medial opening wedge HTO allows early weight-bearing, maintains correction and provides good clinical outcomes. Whilst higher densities of BCP are strong, they do not resorb fully, remaining radiographically visible. This may have implications for the performance of a future knee arthroplasty and caution should therefore be taken.

Faster union rate and better clinical outcomes using autologous bone graft after medial opening wedge high tibial osteotomy

PURPOSE

To compare the radiological bone union rate after medial opening wedge high tibial osteotomy (MOW-HTO) and stabilization using a TomoFix™ plate (Synthes, Oberdorf, Switzerland) in three patient groups.

METHODS

Retrospective analysis of 137 knees that underwent MOW-HTO between January 2014 and January 2017 was using a TomoFix™ plate. Osteotomy gaps were filled with β-tricalcium phosphate (β-TCP) (group A), left unfilled (group B), and subject to autologous bone graft and β-TCP (group C). Radiological bone union using simple radiography was determined by a modified version of the Brosset et al. osteotomy filling index. Clinical outcomes were evaluated using the International Knee Documentation Committee (IKDC) and Lysholm score. Statistical analyses using the Chi-square and ANOVA tests were performed between the groups.

RESULTS

The mean time for radiological bone union was 8.3 ± 3.1 months in group A, 7.2 ± 3.2 in group B and 3.4 ± 1.5 in group C (p = 0.001). There was statistically significant faster bone union in Group C. If the opening distance was more than 10 mm, group A united in 8.6 ± 3.6 months, group B in 8.8 ± 3.4, and group C in 3.5 ± 1.7 (p = 0.001). IKDC and Lysholm knee scores improved significantly (p = 0.004 for IKDC and 0.001 for Lysholm knee scores) in group C when compared to groups A and B at sixth month follow-up. At final follow-up, there was no difference in IKDC and Lysholm knee scores. Less delayed union occurred in group C.

CONCLUSIONS

MOW-HTO with autologous bone graft and β-TCP had the fastest radiological bone union and best clinical scores at 6 month follow-up.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

Early experience of lateral hinge fracture during medial opening-wedge high tibial osteotomy: incidence and clinical outcomes

PURPOSE

Lateral hinge fracture (LHF) during a medial opening-wedge high tibial osteotomy (MOWHTO) is considered to be the main cause of instability, further displacement, loss of correction, malunion, and nonunion. The purposes of this study were to evaluate whether the incidence of LHFs during MOWHTOs has decreased as the number of cases performed over time has increased, and whether the radiographic and clinical outcomes of patients with LHFs were worse than those of patients without LHFs.

MATERIALS AND METHODS

During the period of July 2013 to January 2017, 132 MOWHTOs were performed by a single surgeon using a locking plate (TomoFix^®, DePuySynthes, Solothurn, Switzerland) for the treatment of medial compartment osteoarthritis, with LHFs postoperatively detected in 32 knees (24.2%). To evaluate trends in the incidence of LHFs occurring during MOWHTOs over time, all 132 cases were divided chronologically into four groups of 33 cases and compared. The time for bony union and loss of correction were compared between the LHF group and the non-LHF group using an osteotomy filling index, hip-knee-ankle (HKA) angles, medial proximal tibial angles (MPTA), weight-bearing line (WBL) ratios, and posterior tibial slope (PTS) angles on radiographs. Clinical outcomes were also compared using the Knee Society Scores (KSS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores 1 year post-surgery.

RESULTS

The incidence of LHFs in each group of 33 cases did not decrease over time (21.2%, 27.3%, 24.2%, and 24.2%, respectively, p = 0.954). The time to union was significantly different between the non-LHF group (5.0 months) and the LHF group (7.3 months) (p < 0.001). However, there were no immediate or 1-year postoperative differences in the HKA angles, MPTAs, WBL ratios, or PTS angles between the non-LHF and LHF groups (all p > 0.05). The KSS and WOMAC scores were significantly improved in both groups (all p < 0.001) 1 year post-surgery, without any differences between the groups (p = 0.997 and p = 0.122, respectively).

CONCLUSIONS

LHFs during MOWHTO procedures occurred consistently, with a similar incidence over time. Although patients with LHFs required more time to bony union, they showed similarly favorable radiographic and clinical results as the patients without LHFs 1 year after surgery.

Comparable bone union progression after opening wedge high tibial osteotomy using allogenous bone chip or tri-calcium phosphate granule: a prospective randomized controlled trial

PURPOSE

The purpose of this study is to compare the progression rate of bone union and clinical outcomes of opening wedge high tibial osteotomy (OWHTO) using allogenous bone chip or tri-calcium phosphate (TCP) granule as bone graft materials. The hypothesis was that the bone union progression in OWHTOs using TCP granule grafts would be comparable to that of OWHTOs using allogenous bone chip grafts.

METHODS

Between 2011 and 2013, 54 patients who had undergone OWHTO for genu varum and osteoarthritis were randomized to one of the two groups at five centres. TCP granule was used to fill the defect in 27 patients and lyophilized allogenous bone chip was used in the other 27 patients. The degree of bone union was classified on a five-point scale and evaluated using plain radiographs of the knee at 6 weeks, 3 months, 6 months, and 12 months postoperatively. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, pain Visual Analogue Scale (VAS) score and complications were also evaluated.

RESULTS

The highest degree of bone union observed at 6 and 12 months postoperatively was grade 4, and the number of cases of union progression at each time-point was not significantly different between the two groups (p > 0.05). WOMAC and pain VAS scores also showed no differences between the two groups. No complications were observed during the 12-month period following OWHTO in either group.

CONCLUSION

OWHTO using TCP granule bone substitute showed similar bone union rates and clinical outcomes compared to allogenous bone chip grafts. TCP granule can be used as bone substitutes instead of allogenous bone chip grafts in OWHTO.

LEVEL OF EVIDENCE

Level 1.

Benefits of opposite screw insertion technique in medial open-wedge high tibial osteotomy: A virtual biomechanical study

Background

Alignment correction of the lower limb by medial open-wedge high tibial osteotomy (HTO) is an efficient technique, but loss of correction and hardware failure can occur owing to inadequate fixation. A surgical technique using opposite screw insertion was previously applied for salvage of the lateral hinge fracture, but evidence for its utility as a protective strategy was unclear.

Methods

Finite element models were reconstructed using artificial bone models, commercial bone plate, and locking screws in the HTO model. The 6.5-mm cancellous or 6.5/8.0-mm pretensioned lag screw was virtually inserted from the opposite cortex to the medial tibial plateau. Testing loads were applied for simulating standing and initial sit-to-stand postures. The axial displacement of the posteromedial tibial plateau, which represents the loss of the posteromedial tibial plateau in clinical observation, and stresses on the bone plate, locking screws, and opposite screws were evaluated.

Results

Pretensioned lag screw insertion effectively reduced the loss of posteromedial reduction compared with the HTO model without opposite screw insertion [6.5-mm lag screw, by 50.8% (standing)/56.3% (sit-to-stand); 8.0-mm lag screws, by 51.9% (standing)/57.5% (sit-to-stand); normalised by the performance in the intact model]. The noncompressed opposite cancellous screw slightly reduced the stresses on the bone plate and screws, but did not contribute to the control of reduction loss at the posteromedial tibial plateau. Stresses on screws were lower than those on the corresponding bone plates, so the risk of screw breakage may be low.

Conclusion

The present study revealed that pretensioned opposite lag screw insertion is a simple and effective technique to improve the structural stability in medial open-wedge HTO. Further biomechanical and clinical verification will be required to enhance user confidence in this technique.

The translational potential of this article

The efficacy and advantages of additional opposite lag screw insertion in medial wedge high tibial osteotomy surgery have been described in this current study by a virtual biomechanical evaluation. Basing on this observation, it would worth further clinical trials for clarification and verification in reality.

Development and validation of a finite element model to simulate the opening of a medial opening wedge high tibial osteotomy

Medial opening wedge high tibial osteotomy (MOWHTO) is a surgical procedure intended to alter the coronal and sagittal plane alignment of the lower limb to primarily relieve the symptoms of osteoarthritis in the medial compartment of the knee. The purpose of this work was to develop and validate a finite element model to simulate the opening of a high tibial osteotomy and determine whether a pilot hole at the cortical hinge reduces the risk of lateral cortical fracture. Fifteen models were reconstructed from CT images of eight cadaveric specimens. The validated models indicated that the addition of the pilot hole increased the stresses and likelihood of a type-I and type-II fractures during the opening of a medial open wedge high tibial osteotomy compared to the no-hole condition.

The Effect of Concomitant Arthroscopic Lateral Retinacular Release on Postoperative Patellar Position and Orientation in Open Wedge High Tibial Osteotomy

Purpose

The purpose of this study was to evaluate the effect of concomitant arthroscopic lateral release (LR) in open wedge high tibial osteotomy (OWHTO) by comparing the pre- and postoperative radiological parameters of patellar position and orientation.

Materials and Methods

The study was comprised of 19 knees undergoing OWHTO and concomitant LR and 18 knees undergoing OWHTO alone. Radiological parameters for patellar position and orientation included the Caton-Deschamps index (CDI), Blackburne-Peel index (BPI), patellar tilting angle (PTA), patellar lateral shift (PLS), and patellofemoral distance (PFD), which were evaluated in the preoperative period and at one year after surgery.

Results

Patellar height was significantly reduced after surgery as indicated by the decrease in BPI (p=0.03) in the OWHTO/LR group, and decrease in CDI (p=0.03) and BPI (p=0.04) in the OWHTO alone group. PTA and PLS were significantly reduced after the combined OWHTO/LR procedure (p=0.04 and p=0.04, respectively). By contrast, no significant changes were detected when isolated OWHTO was performed.

Conclusions

OWHTO induced a postoperative decrease in patellar height in both groups. Regarding the change in patellofemoral alignment, concomitant LR in OWHTO significantly decreased lateral patellar tilt and shift, while no significant difference in those parameters were noted in the OWHTO alone knees.

Management of an Infected Nonunion of an Opening-Wedge High Tibial Osteotomy with 2-Stage Implantation of Rotating Hinge Knee Prosthesis

Introduction

High tibial osteotomy (HTO) is a frequent and effective treatment for unicompartmental gonarthritis. Only a few articles are focused on the treatment of infected nonunion.

Patient and Method

A 50-year-old obese patient was operated on by medial opening-wedge HTO. She developed a painful nonunion treated by hardware removal, allograft, and plate fixation. However, the nonunion persisted. 2 years later, cellulitis appeared with an abscess adjacent to the HTO plate. Despite surgical debridement and antibiotics, septic knee arthritis occurred. In a situation of infected nonunion and septic arthritis with chondrolysis, she was scheduled for a 2-stage total knee replacement (TKR). The infected tibial articular block was first resected and replaced by a cement spacer. After a short interval, the TKR was implanted. After 2 years, the patient walked pain-free with good knee function.

Discussion

In the literature, different efficient treatments exist for infected nonunion after HTO, but comprehensive studies are missing for a consensus treatment. Current data are mostly based on case reports, since this pathology is quite rare.

Conclusion

In a difficult situation of infected nonunion with septic knee arthritis, we performed a 2-stage knee prosthesis implantation. This led to an early mobilization and fast recovery.

Comparison of monoplanar versus biplanar medial opening-wedge high tibial osteotomy techniques for preventing lateral cortex fracture

PURPOSE

The purpose of this study was to investigate the mechanical strength of both monoplanar and biplanar medial opening-wedge high tibial osteotomy (MOWHTO) procedures and assess the risk of lateral cortex disruption for both techniques.

METHODS

Twelve synthetic tibia models with cortical shells were used as test models. Saw cuts for monoplanar MOWHTO and biplanar MOWHTO were generated on the test models in equal numbers (n = 6 for both groups). Wedge opening load and wedge gap distance were evaluated via compressive tests.

RESULTS

The mean gap distance just before the lateral cortex fracture in the monoplanar group was 14.7 ± 2.9 mm, which was significantly narrower than that in the biplanar group of 19.1 ± 2.0 mm (p = 0.015). The mean load just before the occurrence of lateral cortex fracture of 32.4 ± 3.2 N in the monoplanar osteotomy group was significantly lower than that in the biplanar osteotomy group of 111.8 ± 9.3 N (p = 0.009).

CONCLUSION

Performing a MOWHTO via the biplanar rather than the monoplanar technique allows larger-sized wedges to be opened with less risk of lateral cortical fracture. Thus, larger gaps can be opened and higher angle corrections can be achieved using the biplanar osteotomy procedure. From a clinical viewpoint, the biplanar osteotomy technique reduced the risk of lateral cortical hinge fracture during MOWHTO.

Locking plate versus non-locking plate in open-wedge high tibial osteotomy: a meta-analysis

PURPOSE

The purpose of this study was to conduct a meta-analysis to determine whether the locking plate or non-locking plate results in better opening-wedge high tibial osteotomy (OWHTO) outcomes.

METHODS

The MEDLINE, EMBASE, COCHRANE, and KOREAMED register databases were searched for studies. The eligibility criteria for inclusion in the review were studies that compared the locking plate with the non-locking plate for OWHTO, and those that provided clear descriptions of surgical techniques and outcomes. The key outcomes of interest were union rate, correction loss angle, correction loss rate, and full weight-bearing starting point. The statistical software "RevMan" was used in statistical analysis.

RESULTS

Five studies were included in the meta-analysis. Among their reported results, there were no differences in the incidence of union [risk ratio (RR) = 1.01, p = 0.34], non-locking plate was associated with lower incidence of correction maintenance (RR = 1.13, p = 0.0006) and greater angle of correction loss [mean difference (MD) = -2.06, p < 0.00001], and locking plate was associated with a significant improvement in Knee society score and function score (MD = 5.77, p < 0.0001; MD = 7.50, p = 0.0005).

CONCLUSIONS

Locking plate provides better clinical outcomes and reduced correction loss rates and angles as compared to non-locking plate for fixation with OWHTO.

LEVEL OF EVIDENCE

IV.

Medial Open Wedge High Tibial Osteotomy for Varus Malunited Tibial Plateau Fractures

PURPOSE

To analyze radiologic and functional outcomes of varus malunited tibial plateau fractures managed with medial open wedge high tibial osteotomy (MOHTO).

METHODS

Eighteen patients with symptomatic varus malunited tibial plateau fractures with less than stage II arthritic changes managed from July 2009 to October 2013 were included. Patients with complex intra-articular step malunions and severe arthritic changes (stage III and IV) were excluded. Initially, diagnostic arthroscopy was performed followed by MOHTO stabilized with locking plate and tricortical autograft (n = 11, 61%) or a Puddu plate and allograft (n = 7, 39%). Patients were evaluated radiologically for union, medial proximal tibial angle, and tibial slope angle, and functional assessment was performed with a knee outcome survey based on activities of daily living.

RESULTS

The mean follow-up duration was 41.7 ± 12.1 months (range 25-61); all patients achieved radiologic union by a mean duration of 4.3 ± 1.2 months (range 3-8). The mean medial proximal tibial angle improved from 75.3° ± 3.7° (range 70.5°-85.2°) to a postoperative angle of 83.8° ± 3.6° (range 77.5°-90.4°) (P < .001). In 12 patients, an abnormal mean anterior slope of -5.5° ± 3.0° (range -1.1° to -13°) was corrected to a postoperative posterior slope of 5.8° ± 4.4° (range -1.1° to 14.1°) (P < .001). In 6 patients, a mean posterior slope of 17.4° ± 10.5° (range 1.4°-33°) was corrected to a postoperative posterior slope of 14.08° ± 5.6° (range 7.4-21.3) (P = .214). The mean knee outcome survey scores preoperatively were 25% ± 9.68% (range 8%-48%) and postoperatively were 85% ± 11.18% (range -52% to 98%, P < .001).

CONCLUSIONS

MOTHO for varus malunited tibial plateau fractures is safe and effective procedure that provides excellent functional outcomes, acceptable radiologic outcomes, and carries minimal complications.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Role of High Tibial Osteotomy in Cartilage Regeneration - Is Correction of Malalignment Mandatory for Success?

Malalignment of the knee can cause debilitating symptoms such as pain, resulting in a decline in function and mobility. Surgical options that exist to address this problem include realignment osteotomies and joint replacements. Realignment osteotomies are the more appropriate options in certain patient populations, especially with regard to age and level of activity. Since a high tibial osteotomy (HTO) was first used to manage malalignment of the knee and osteoarthritis, different techniques involving the use of specialized implants have been developed and further refined to good effect. There has also since been much research into the field of cartilage restoration techniques, both as a standalone treatment option and as an adjunct to a realignment osteotomy. This review attempts to detail the origin and the evolution of HTO, particularly in regard to combining this tried and tested procedure with adjunct cartilage restoration techniques, and the overall patient outcomes. A literature search on PubMed was performed, and articles pertaining to the outcomes of the use of an HTO and cartilage restoration techniques were reviewed. The literature in this field indicates good outcomes in terms of objective measurements of cartilage regeneration (such as arthroscopic visualization and magnetic resonance imaging evaluation) and subjective patient outcome scoring systems (such as the International Knee Documentation Committee and Lysholm scores) with a realignment osteotomy alone, and studies have shown that patient outcomes can be further improved with the use of a cartilage restoration procedure as an adjunct.

Complications and Short-Term Outcomes of Medial Opening Wedge High Tibial Osteotomy Using a Locking Plate for Medial Osteoarthritis of the Knee

Purpose

The purpose of this study was to investigate complications and radiologic and clinical outcomes of medial opening wedge high tibial osteotomy (MOWHTO) using a locking plate.

Materials and Methods

This study reviewed 167 patients who were treated with MOWHTO using a locking plate from May 2012 to June 2014. Patients without complications were classified into group 1 and those with complications into group 2. Medical records, operative notes, and radiographs were retrospectively reviewed to identify complications. Clinically, Oxford Knee score and Knee Injury and Osteoarthritis Outcome score (KOOS) were evaluated.

Results

Overall, complications were observed in 49 patients (29.3%). Minor complications included lateral cortex fracture (15.6%), neuropathy (3.6%), correction loss (2.4%), hematoma (2.4%), delayed union (2.4%), delayed wound healing (2.4%), postoperative stiffness (1.2%), hardware irritation (1.2%), tendinitis (1.2%), and hardware failure without associated symptoms (0.6%). Major complications included hardware failure with associated symptoms (0.6%), deep infection (0.6%), and nonunion (0.6%). At the first-year follow-up, there were no significant differences in radiologic measurements between groups 1 and 2. There were no significant differences in knee scores except for the KOOS pain score.

Conclusions

Our data showed that almost all complications of the treatment were minor and the patients recovered without any problems. Most complications did not have a significant impact on radiologic and clinical outcomes.

Complications associated with opening wedge high tibial osteotomy--A review of the literature and of 15 years of experience

BACKGROUND

Complication rates following opening wedge high tibial osteotomy (OWHTO) is an issue that has not been comprehensively addressed in current literature.

METHODS

We performed a retrospective study of local patients who underwent OWHTO for isolated medial compartment knee osteoarthritis from 1997 to 2013. We analysed survivorship and complication rates and compared this to a literature review of previously reported data.

RESULTS

One hundred and fifteen patients met the inclusion criteria. Mean follow-up=8.4 years. Mean age=47 (range 32 to 62). Mean Body Mass Index (BMI)=29.1 (range 20.3 to 40.2). Devices used consisted of Tomofix (72%), Puddu plate (21%) and Orthofix (seven percent) (no significant differences in age/sex/BMI). Wedge defects were filled with autologous graft (30%), Chronos (35%) or left empty (35%). Five years survival rate (without requiring conversion to arthroplasty)=80%. Overall complication rate=31%. Twenty five percent of patients suffered 36 complications including minor wound infections (9.6%), major wound infections (3.5%), metalwork irritation necessitating plate removal (seven percent), non-union requiring revision (4.3%), vascular injury (1.7%), compartment syndrome (0.9%), and other minor complications (four percent). No thromboembolic complications were observed.

CONCLUSION

No significant differences existed in complication rates following OWHTO relative to BMI, implant type, type of bone graft used or patient age at surgery. When the complications from OWHTO were analysed closely they appear higher than previously reported in the literature; however serious complications appear rare. LEVEL OF EVIDENCE 3: Retrospective cohort study.

Is Bone Grafting Necessary in Opening Wedge High Tibial Osteotomy? A Meta-Analysis of Radiological Outcomes

Purpose

Bone grafting in opening wedge high tibial osteotomy (OWHTO) is still controversial. The purpose of this study is to compare the radiological outcomes of OWHTO with bone graft (autogenous, allogenous, and synthetic bone graft) and those without bone graft.

Materials and Methods

PubMed, MEDLINE, EMBASE and Cochrane Register of Studies databases were searched using specific inclusion and exclusion criteria for radiological studies involving OWHTO with bone graft and without bone graft groups. All reported delayed union, nonunion and correction loss were analyzed. Data were searched from the time period of January 2000 through July 2014. In addition, a modified Coleman methodology score (CMS) system was used to assess the methodological quality of the included studies.

Results

Twenty-five studies with a mean CMS value of 77 (range, 61 to 85 score) were included. In total, 1,841 patients underwent OWHTO using 4 different procedures for bone graft: autobone graft (n=352), allobone graft (n=547), synthetic bone graft (n=541) and no bone graft (n=401). There was a similar tendency for delayed union, nonunion and correction loss rate among the osteotomy space filling methods.

Conclusions

The meta-analysis showed there was a similar tendency for radiological union and correction maintenance among patients undergoing OWHTO regardless of the type of bone in all of the studies. However, the currently available evidence is not sufficient to strongly support the superiority of OWHTO with bone graft to OWHTO without bone graft.

A report of nonunion at medial wedge high tibial osteotomy site and its management

High tibial osteotomy (HTO) is an accepted treatment option for correcting deformities and reducing pain in the treatment of uni-compartment osteoarthritis of the knee. The principle is to redistribute the weight-bearing load. Medial open wedge HTO (MOWHTO) has gained popularity over lateral closed wedge osteotomy due to its decreased incidence of complications. MOWHTO surgical techniques have many variations in fixation techniques and in the use of bone grafts or bone substitute augmentation. In spite of the existing guidelines, there are no clear indications of grafting at the osteotomy site. Delayed union and nonunion although are possible complications, nonunion is especially rarely reported. Thus authors in this case report, like to point attention towards this under-reported complication and its management.

The validity of the classification for lateral hinge fractures in open wedge high tibial osteotomy

The objective of this study was to validate the efficacy of Takeuchi classification for lateral hinge fractures (LHFs) in open wedge high tibial osteotomy (OWHTO). In all 74 osteoarthritic knees (58 females, 16 males; mean age 62.9 years, standard deviation 7.5, 42 to 77) were treated with OWHTO using a TomoFix plate. The knees were divided into non-fracture (59 knees) and LHF (15 knees) groups, and the LHF group was further divided into Takeuchi types I, II, and III (seven, two, and six knees, respectively). The outcomes were assessed pre-operatively and one year after OWHTO. Pre-operative characteristics (age, gender and body mass index) showed no significant difference between the two groups. The mean Japanese Orthopaedic Association score was significantly improved one year after operation regardless of the presence or absence of LHF (p = 0.0015, p < 0.001, respectively). However, six of seven type I cases had no LHF-related complications; both type II cases had delayed union; and of six type III cases, two had delayed union with correction loss and one had overcorrection. These results suggest that Takeuchi type II and III LHFs are structurally unstable compared with type I. Cite this article: Bone Joint J 2015;97-B:1226-31.

The cost-effectiveness of surgical treatment of medial unicompartmental knee osteoarthritis in younger patients: a computer model-based evaluation

BACKGROUND

Surgical options for the management of medial compartment osteoarthritis of the varus knee include high tibial osteotomy, unicompartmental knee arthroplasty, and total knee arthroplasty. We sought to determine the cost-effectiveness of high tibial osteotomy and unicompartmental knee arthroplasty as alternatives to total knee arthroplasty for patients fifty to sixty years of age.

METHODS

We built a probabilistic state-transition computer model with health states defined by pain, postoperative complications, and subsequent surgical procedures. We estimated transition probabilities from published literature. Costs were determined from Medicare reimbursement schedules. Health outcomes were measured in quality-adjusted life-years (QALYs). We conducted analyses over patients' lifetimes from the societal perspective, with health and cost outcomes discounted by 3% annually. We used probabilistic sensitivity analyses to account for uncertainty in data inputs.

RESULTS

The estimated discounted QALYs were 14.62, 14.63, and 14.64 for high tibial osteotomy, unicompartmental knee arthroplasty, and total knee arthroplasty, respectively. Discounted total direct medical costs were $20,436 for high tibial osteotomy, $24,637 for unicompartmental knee arthroplasty, and $24,761 for total knee arthroplasty (in 2012 U.S. dollars). The incremental cost-effectiveness ratio (ICER) was $231,900 per QALY for total knee arthroplasty and $420,100 per QALY for unicompartmental knee arthroplasty. Probabilistic sensitivity analyses showed that, at a willingness-to-pay (WTP) threshold of $50,000 per QALY, high tibial osteotomy was cost-effective 57% of the time; total knee arthroplasty, 24%; and unicompartmental knee arthroplasty, 19%. At a WTP threshold of $100,000 per QALY, high tibial osteotomy was cost-effective 43% of time; total knee arthroplasty, 31%; and unicompartmental knee arthroplasty, 26%.

CONCLUSIONS

In fifty to sixty-year-old patients with medial unicompartmental knee osteoarthritis, high tibial osteotomy is an attractive option compared with unicompartmental knee arthroplasty and total knee arthroplasty. This finding supports greater utilization of high tibial osteotomy for these patients. The cost-effectiveness of high tibial osteotomy and of unicompartmental knee arthroplasty depend on rates of conversion to total knee arthroplasty and the clinical outcomes of the conversions.

Treatment for Staphylococcus aureus infection following open wedge high tibial osteotomy using antibiotic-impregnated calcium phosphate cement

This report describes a case of Staphylococcus aureus infection following open wedge high tibial osteotomy, which was successfully treated with by implant removal and replacement with antibiotic-impregnated calcium phosphate cement along with external fixation. The infection occurred 7 months after primary surgery and was treated by implant removal, debridement, external fixation, and application of vancomycin impregnated calcium phosphate cement to fill the defect. Subsequently, the infection resolved completely, and the osteotomy healed with no correction loss. Compared with conventional bone cement, calcium phosphate cement might be an optimal material for certain cases of infection after open wedge high tibial osteotomy because of its higher antibiotic retention, biocompatibility, osteoconductivity, and compatibility with heatlabile antibiotics.

LEVEL OF EVIDENCE

V.

Comparison of theoretical fixation stability of three devices employed in medial opening wedge high tibial osteotomy: a finite element analysis

Background

Medial open wedge high tibial osteotomy is a well-established procedure for the treatment of unicompartmental osteoarthritis and symptomatic varus malalignment. We hypothesized that different fixation devices generate different fixation stability profiles for the various wedge sizes in a finite element (FE) analysis.

Methods

Four types of fixation were compared: 1) first and 2) second generation Puddu plates, and 3) TomoFix plate with and 4) without bone graft. Cortical and cancellous bone was modelled and five different opening wedge sizes were studied for each model. Outcome measures included: 1) stresses in bone, 2) relative displacement of the proximal and distal tibial fragments, 3) stresses in the plates, 4) stresses on the upper and lower screw surfaces in the screw channels.

Results

The highest load for all fixation types occurred in the plate axis. For the vast majority of the wedge sizes and fixation types the shear stress (von Mises stress) was dominating in the bone independent of fixation type. The relative displacements of the tibial fragments were low (in μm range). With an increasing wedge size this displacement tended to increase for both Puddu plates and the TomoFix plate with bone graft. For the TomoFix plate without bone graft a rather opposite trend was observed.

For all fixation types the occurring stresses at the screw-bone contact areas pulled at the screws and exceeded the allowable threshold of 1.2 MPa for at least one screw surface. Of the six screw surfaces that were studied, the TomoFix plate with bone graft showed a stress excess of one out of twelve and without bone graft, five out of twelve. With the Puddu plates, an excess stress occurred in the majority of screw surfaces.

Conclusions

The different fixation devices generate different fixation stability profiles for different opening wedge sizes. Based on the computational simulations, none of the studied osteosynthesis fixation types warranted an intransigent full weight bearing per se. The highest fixation stability was observed for the TomoFix plates and the lowest for the first generation Puddu plate. These findings were revealed in theoretical models and need to be validated in controlled clinical settings.

Adverse event rates and classifications in medial opening wedge high tibial osteotomy

BACKGROUND

Previously reported complications in medial opening wedge (MOW) high tibial osteotomy (HTO) vary considerably in both rate and severity.

PURPOSE

(1) To determine the rates of adverse events in MOW HTO classified into different grades of severity based on the treatments required and (2) to compare patient-reported outcomes between the different adverse event classifications.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

All patients receiving MOW HTO at a single medical center from 2005 to 2009 were included. Internal fixation was used in all cases, with either a nonlocking (Puddu) or locking (Tomofix) plate. Patients were evaluated at 2, 6, and 12 weeks; 6 and 12 months; and annually thereafter. Types of potential surgical and postoperative adverse events, categorized into 3 classes of severity based on the subsequent treatments, were defined a priori. Medical records and radiographs were then reviewed by an independent observer. The Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores were compared in subgroups of patients based on the categories of adverse events observed.

RESULTS

A total of 323 consecutive procedures (242 males) were evaluated (age, mean ± standard deviation, 46 ± 9 years; body mass index, mean ± standard deviation, 30 ± 5 kg/m(2)). Adverse events requiring no additional treatment (class 1) were undisplaced lateral cortical breaches (20%), displaced (>2 mm) lateral hinge fracture (6%), delayed wound healing (6%), undisplaced lateral tibial plateau fracture (3%), hematoma (3%), and increased tibial slope ≥10° (1%). Adverse events requiring additional or extended nonoperative management (class 2) were delayed union (12%), cellulitis (10%), limited hardware failure (1 broken screw; 4%), postoperative stiffness (1%), deep vein thrombosis (1%), and complex regional pain syndrome (CRPS) type 1 (1%). Adverse events requiring additional or revision surgery and/or long-term medical care (class 3) were aseptic nonunion (3%), deep infection (2%), CRPS type 2 (1%), and severe hardware failure with loss of correction (1%). Additional surgery rate was 3%. Class 1 and 2 adverse events did not affect patient-reported outcomes at 6, 12, or 24 months postoperatively. Patients with class 3 adverse events had significantly lower total WOMAC scores at 6 months but not at 12 or 24 months postoperatively.

CONCLUSION

The most common adverse event in MOW HTO requiring extended nonoperative treatment (class 2) is delayed union (12%). The rate of severe adverse events requiring additional surgery and/or long-term medical care (class 3) is low (7%).

The weight-bearing scanogram technique provides better coronal limb alignment than the navigation technique in open high tibial osteotomy

BACKGROUND

Successful outcomes following high tibial osteotomy (HTO) require precise realignment of the mechanical axis of the lower extremity. The present study investigated whether the weight-bearing limb scanogram (WBS) technique provided a more accurate mechanical axis realignment than the navigation technique in open high tibial osteotomy (OHTO).

METHODS

This prospective study involved 80 knees (78 patients) undergoing OHTO. The WBS technique was used in 40 knees and the navigation technique in 40 knees. Each technique was performed by a different surgeon in a different hospital. Postoperative coronal limb alignment was assessed using the weight-bearing line (WBL) ratio on full-length standing hip-to-ankle radiographs.

RESULTS

We found that the mean postoperative WBL ratio was greater in the WBS compared to the navigation group (p=0.001), and hence the ratio for the WBS group was closer to the ratio target of 62%. There was a greater proportion of WBL ratio outliers in the navigation group than the WBS group (25% vs. 10%, p=0.034).

CONCLUSION

We conclude that the WBS technique was more accurate than the navigation technique for restoration of coronal leg alignment in OHTO.

LEVEL OF EVIDENCE

Level II.

Complications of osteotomies about the knee

High tibial osteotomy and distal femoral osteotomy are 2 popular techniques for the treatment of monocompartmental osteoarthritis of the knee joint in young patients. Injury to the popliteal neurovascular bundle is still considered to be the most severe complication during an osteotomy procedure even if the rate of occurrence is very low. Loss of correction and hardware failures are more frequent, but not as devastating. Patella baja and modification of tibial slope are associated with high tibial osteotomy. In contrast, complications most commonly associated with distal femoral osteotomy include nonunion and failure of the internal fixation. In general with evolution of techniques and fixation devices, complication rates seem to be reduced. A summary and literature review of complications associated with knee osteotomies will be discussed in this paper.

Comparison between Autogenous Bone Graft and Allogenous Cancellous Bone Graft in Medial Open Wedge High Tibial Osteotomy with 2-Year Follow-up

PURPOSE

To compare the radiographic and clinical results of medial open wedge high tibial osteotomy (OWHTO) using autogenous bone graft and allogenous cancellous bone graft for medial compartment osteoarthritis of the knee with two-year follow-up.

MATERIALS AND METHODS

Fifty-one patients (52 knees) who underwent medial OWHTO from October 2007 to April. 2010 were included in the study. The patients were divided into group I (n=29) that received an autogenous tricortical bone graft and group II (n=23) that received an allogenous cancellous bone chip graft. The radiographic parameters (preoperative anatomical and mechanical femorotibial angles, modified tibial bone varus angle, and posterior tibial slope), clinical parameters, bone union period, and complications were evaluated from medical records.

RESULTS

The radiographic and clinical outcomes did not show significant difference between two groups. The average bone union period was 11.7 weeks in group I and 12.1 weeks in group II. The visual analog scale score on the first postoperative day was significantly higher in group I than group II.

CONCLUSIONS

Medial OWHTO using allogenous cancellous bone graft for medial compartment osteoarthritis of the knee can be considered as an alternative treatment method that provides equivalent radiographic and clinical results of OWHTO using autogenous bone graft and causes less immediate postoperative pain.

Infections after high tibial osteotomy

PURPOSE

High tibial osteotomy is an established method in the treatment for knee osteoarthritis. Infections are a rare but severe complication that might endanger the clinical, radiological and functional outcome and might require several surgical revisions.

METHODS

A systematic literature review was performed through PubMed until November 2011. Search terms were "HTO" or "(high) tibial osteotomy", alone or in combination with "infection(s)", "infected" or "septic". Only articles focussing on the infection treatment or analysis of risk factors for emergence of infection after high tibial osteotomy were included.

RESULTS

A total of 26 studies could be identified. Seven studies were published before and 19 in or after 2000. One study had a level of evidence II, five level of evidence III and 20 level of evidence IV. Superficial infections were found in 1-9% and deep infections in 0.5-4.7% of the cases. Pin tract infections occurred in 2-71% of the cases. One study reported on a secondary bacterial arthritis in 4.5% of the cases. An oblique skin incision, non-smokers and a one-day hospitalization were found to be risk factors for infection emergence. Depending on the type of infection, treatment consisted of oral or systemic antibiotic therapy, alone or in combination with surgical revision, debridement and hardware removal. In some cases, antibiotic-loaded cement beads were inserted for local antibiotic therapy.

CONCLUSION

Infections after high tibial osteotomy are rare. Current data about infection rates, infection localization, risk factors for emergence of infection and treatment options allow not for a generalization of conclusions. A large multi-centre study is required to develop a diagnostic and therapeutic algorithm.

LEVEL OF EVIDENCE

IV.

An early sign of intraarticular fracture of the lateral tibial plateau during opening wedge high tibial osteotomy

Intraarticular fracture of the lateral tibial plateau is one of the serious complications in medial opening wedge high tibial osteotomy (HTO). We present a case of fracture of the lateral tibial plateau during medial opening wedge HTO. The authors have found the early fracture sign, uneven divergence gap of proximal and distal parts during enlargement of the osteotomy site with a dilatator, a useful marker for early detection and prevention of fracture extending.

A "safe zone" in medial open-wedge high tibia osteotomy to prevent lateral cortex fracture

PURPOSE

The purpose of this cadaveric study was to study the effect of plane of osteotomy on incidence of lateral cortex fracture and to define a "safe zone" through which medial open-wedge high tibial osteotomy (HTO) could be performed with minimal risk of lateral cortex fracture.

METHODS

Medial open HTO was performed in nine fresh frozen human cadavers (18 knees) with each specimen randomly assigned to a "safe zone" osteotomy (group A, between the tip of the fibular head and the circumference line of the fibular head), or a lower level osteotomy (group B, distal to the circumference line of the fibular head).

RESULTS

Six out of nine knees developed lateral cortex fracture in group B compared to none in group A (P = 0.009) when the osteotomy site was distracted to a maximum of 20 mm.

CONCLUSION

Directing the plane of the osteotomy toward the "safe zone" significantly reduces the risk of lateral cortex fracture compared to an osteotomy, which is directed at a lower level. Confining the plane of a medial open HTO to within the "safe zone" can prevent lateral cortex fracture and subsequent loss of correction.

Finite element analysis of Puddu and Tomofix plate fixation for open wedge high tibial osteotomy

The use of open wedge high tibial osteotomy (HTO) to correct varus deformity of the knee is well established. However, the stability of the various implants used in this procedure has not been previously demonstrated. In this study, the two most common types of plates were analysed (1) the Puddu plates that use the dynamic compression plate (DCP) concept, and (2) the Tomofix plate that uses the locking compression plate (LCP) concept. Three dimensional model of the tibia was reconstructed from computed tomography images obtained from the Medical Implant Technology Group datasets. Osteotomy and fixation models were simulated through computational processing. Simulated loading was applied at 60:40 ratios on the medial:lateral aspect during single limb stance. The model was fixed distally in all degrees of freedom. Simulated data generated from the micromotions, displacement and, implant stress were captured. At the prescribed loads, a higher displacement of 3.25 mm was observed for the Puddu plate model (p<0.001). Coincidentally the amount of stresses subjected to this plate, 24.7 MPa, was also significantly lower (p<0.001). There was significant negative correlation (p<0.001) between implant stresses to that of the amount of fracture displacement which signifies a less stable fixation using Puddu plates. In conclusion, this study demonstrates that the Tomofix plate produces superior stability for bony fixation in HTO procedures.

A retrospective analysis of medial opening wedge high tibial osteotomy for varus osteoarthritic knee

BACKGROUND

Medial opening wedge high tibial osteotomy (MOWHTO) has proven to be an effective treatment for varus osteoarthritic knees. Various methods of fixation with different implant types and using either bone grafts or bone substitutes have been reported. We performed non-locking T-buttress plate fixation with autologous iliac bone graft augmentation, which is defined here as the traditional method, and locking compression plate fixation without any bone graft or bone substitute. We aimed to compare bone union and complications of these two MOWHTO techniques.

MATERIALS AND METHODS

Between June 2005 and December 2007, 50 patients who underwent MOWHTO (a total of 60 knees) were retrospectively reviewed and classified into two groups: group A, which consisted of 26 patients (30 knees) was treated using T-buttress plate fixation with autologous iliac bone graft augmentation and group B, which consisted of 24 patients (30 knees) was operated upon using a medial high tibial locking compression plate without any augmentation. Demographic characteristics and radiographic outcomes, including union rate, time to union, medial osteotomy defects, and complications, were collected and compared between the two groups. The progress of all patients was followed for at least 2 years.

RESULTS

All osteotomies united within 12 weeks after surgery. Group B had slightly longer time to union than group A (10.3 weeks and 9.5 weeks, respectively; P = 0.125). A significantly higher incidence of medial defects after osteotomy was reported in the locking compression plate group (P = 0.001). A total of 5 (8.3%) knees had complications. In group A, one knee had a superficial wound infection and another knee had a lateral tibial plateau fracture without significant loss of correction. In group B, one knee had screw penetration into the knee joint and two knees had local irritation that required the removal of the hardware.

CONCLUSION

Locking compression plate fixation without the use of bone grafts or bone substitutes provides a satisfactory union rate and an acceptable complication rate when compared to the traditional MOWHTO technique. Thus, we recommend using this technique for treating unicompartmental medial knee osteoarthritis.