Prospective evaluation of a new plate fixator for valgus-producing medial open-wedge high tibial osteotomy

Effect of medial open wedge high tibial osteotomy on progression of patellofemoral osteoarthritis

PURPOSE

This study aimed to investigate the effect of medial open wedge high tibial osteotomy (MOWHTO) on patellofemoral joint osteoarthritis (PF OA) progression and its outcome according to the degree of preexisting PF OA.

MATERIALS AND METHODS

Patients who underwent biplane MOWHTO between January 2006 and December 2018 were retrospectively reviewed. The patients were divided into two groups according to the degree of PF OA: non-PF OA [Kellgren-Lawrence (K-L) grade 0-1] and PF OA (K-L grade 2-3). Propensity score matching was performed between the two groups, and comparative analysis was performed on clinical scores and radiographic parameters and grade.

RESULTS

After propensity score matching, 83 patients were selected for each group. At postoperative follow-up, clinical scores were improved significantly compared with preoperative scores in both groups; however, there were no significant differences between the groups. There were also no significant differences between the two groups in radiographic parameters. The radiographic grade of PF OA indicated a slight progression in osteoarthritis in both groups; however, PF OA tended to progress further in the PF OA group.

CONCLUSIONS

MOWHTO did not result in significant differences in outcomes at postoperative follow-up; however, preexisting PF OA contributed to PF OA progression after MOWHTO.

Risk Factors Affecting Return to Sports and Patient-Reported Outcomes After Opening-Wedge High Tibial Osteotomy in Active Patients

Background:

Although opening-wedge high tibial osteotomy (OWHTO) is favored for active patients who expect to return to sports, there is still a lack of robust evidence for factors affecting their recovery.

Purpose:

To identify (1) risk factors leading to a decreased level of return to preoperative sports after OWHTO and (2) patient characteristics and intraoperative factors influencing patient-reported outcomes after return to sports.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Included were 69 patients who underwent OWHTO and who expected to return to their preoperative level of sports, measured as a Tegner activity level ≥2. All included patients had a minimum of 1 year of follow-up data. Logistic regression analyses were performed to assess the effect of independent variables on the level of return to preoperative sports after surgery; the independent variables were age, sex, body mass index, preoperative Tegner score, preoperative Kellgren-Lawrence grade, preoperative percentage of mechanical axis (%MA), opening gap width, concomitant meniscal treatment, postoperative %MA, postoperative medial proximal tibial angle (MPTA), and postoperative posterior tibial slope. Univariate and multiple regression analyses were performed to assess for influencing factors on postoperative International Knee Documentation Committee (IKDC) subjective scores in patients who were able to return to sports.

Results:

Of the 69 patients, 51 (73.9%) returned to sports after OWHTO. High preoperative Tegner scores were statistically associated with a decrease in return to sports (odds ratio, 1.494; P = .033). Multiple regression analysis (n = 46 patients) identified that a higher postoperative MPTA was associated with a decreased IKDC subjective score after return to sports (r = –0.345; P = .019).

Conclusion:

Higher postoperative MPTA was associated with the worsening of patient-reported outcomes among those patients who did return to their preoperative sports after OWHTO. Also, participation in high-activity sports was confirmed to be a significant risk factor for a decreased rate of return to preoperative sports. These findings can support preoperative planning and intraoperative decision making, particularly for active patients.

Return to Work and Sport After Proximal Tibial Osteotomy and the Effects of Opening Versus Closing Wedge Techniques on Adverse Outcomes: A Systematic Review and Meta-analysis

BACKGROUND

Although many studies have reported successful functional outcomes after proximal tibial osteotomy (PTO), a paucity of literature has sought to quantify outcomes and current rates of return to sport (RTS) and return to work (RTW) after PTO.

PURPOSE

To (1) determine current rates of RTS and RTW after PTO and (2) quantify the incidence of complications and conversion to total knee arthroplasty (TKA) after PTO for all patients as well as those undergoing opening and closing wedge PTO.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

The Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed (2008-2019), EMBASE (2008-2019), and MEDLINE (2008-2019) databases were queried. Data pertaining to article information, patient demographics, surgical techniques, rates of complication and conversion to TKA, patient-reported outcome scores, RTS, and RTW were extracted. Data were synthesized, and a random effects meta-analysis of proportions using continuity correction methods was performed to determine the proportion of patients receiving opening and closing wedge PTO who experienced adverse events.

RESULTS

The review and meta-analysis included 33 studies involving 1914 patients who underwent PTO with a weighted mean ± SD age of 50.3 ± 9.9 years and body mass index of 26.9 ± 2.3 kg/m². The pooled RTS and RTW rates were 75.7% (range, 55%-100%) in 814 patients and 80.8% (range, 41%-100%) in 505 patients, respectively. The pooled TKA rate was 12.5% (range, 0%-35.7%) at a mean of 70.6 months and the pooled complication rate was 11.1% (range, 0%-28.6%). The overall random pooled summary estimate of the proportion of patients who underwent opening wedge PTO and subsequently converted to TKA was 2.0% (95% CI, 1.0%-4.0%; I² = 63.65) at a mean of 43.4 ± 31.9 months and who experienced a complication was 6.0% (95% CI, 3.0%-9.0%; I² = 87.10%). For closing wedge PTO, the proportion of patients who converted to TKA was 5.0% (95% CI, 1.0%-9.0%; I² = 93.1%) and experienced a complication was 2.0% (95% CI, 1.0%-3.0%; I² = 90.0%). Only 53.8% of studies that referenced RTS provided postoperative RTS rates, and 80% of studies that referenced RTW provided RTW rates. Only 1 study defined RTS criteria, no studies defined RTW criteria, and 31 different outcome measures were reported across all studies.

CONCLUSION

Patients undergoing PTO for osteoarthritis, cartilage defects, and symptomatic malalignment of the knee experience high rates of RTS and RTW. These patients also experience low rates of complications and conversion to TKA, regardless of opening or closing wedge technique. Significant heterogeneity exists with regard to criteria used to define RTS and RTW and patient-reported outcome measures used to assess clinical and functional improvements after PTO.

Plate removal without loss of correction after open-wedge high tibial osteotomy is possible when posterior cortex bone union reaches osteotomy gap center even in incompletely filled gaps

PURPOSE

The study aimed to evaluate the optimal timing for plate removal after open-wedge high tibial osteotomy (OWHTO) without loss of correction and to investigate risk factors for loss of correction after plate removal. The study presents the hypothesis that plate removal without loss of correction was possible when gap filling reached zone 2 (25-50%) on anteroposterior radiographs.

METHODS

Ninety-one patients (101 knees) who underwent OWHTO using the TomoFix^® plate were enrolled. Plate removal was performed at an average 16.4 ± 5.4 months after OWHTO. Clinical evaluation included plate-related symptoms, the Japanese Orthopedic Association Knee Score (JOA score), and Oxford Knee Score (OKS). Radiological outcomes, including the hip-knee-ankle angle (HKA), weight-bearing line ratio (WBLR), medial proximal tibial angle (MPTA), and posterior tibial slope (PTS), were evaluated preoperatively, at plate removal and at 1 year after plate removal. Computed tomography (CT) was performed at plate removal to evaluate the flange bone union, progression rates of gap filling, and posterior cortex bone union. In addition, the risk factors for loss of correction after plate removal were evaluated.

RESULTS

At plate removal, 63 (62.4%) knees had plate-related symptoms (mild, 56 knees; moderate, 7 knees; severe, 0). After plate removal, the JOA score did not change, whereas OKS further improved; six knees developed loss of correction. On CT evaluation at plate removal, the flange bone union was achieved in all cases; the progression rates of gap filling and posterior cortex bone union were 47.0% ± 16.6% and 62.8% ± 16.5%, respectively. A posterior cortex union rate of < 43.3% was the only predictor for loss of correction after plate removal (odds ratio: 1.38, P < 0.01).

CONCLUSIONS

Plate removal without loss of correction after OWHTO was possible when bone union of the posterior cortex reached the center of the osteotomy gap even in incompletely filled gaps.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.

Plate-related results of opening wedge high tibial osteotomy with a carbon fiber reinforced poly-ether-ether-ketone (CF-PEEK) plate fixation: a retrospective case series of 346 knees

BACKGROUND

While open wedge high tibial osteotomy (owHTO) is an established standard procedure to treat medial osteoarthritis of the knee in combination with varus deformity, it bears the risk of postoperative hardware failures and lateral cortical hinge fractures. This in turn can lead to an accelerated osteoarthritis, non-union, or a loss of correction accuracy. The purpose of the study was to evaluate the radiologic outcomes of owHTO with a carbon fiber reinforced poly-ether-ether-ketone (CF-PEEK) plate fixation in patients with medial osteoarthritis and varus deformity.

METHODS

Three hundred twenty-four consecutive patients (346 knees) who were treated with owHTO using the PEEKPower HTO plate were included in this retrospective study; 89.9% of the patients were overweight or obese. Patients were followed by conventional radiographs over a 12-month period. Typical plate-related results such as the time and quality of gap healing as well as the correction accuracy were analyzed. Furthermore, the number of lateral cortex fractures was determined.

RESULTS

Bony consolidation was observed after a mean gap healing time of 4.0 ± 1.7 months independent on the patients' weight (p = 0.2302). With increasing gap sizes, bony healing was significantly prolonged (p < 0.001). Additionally, patients with greater gap sizes had a significantly increased risk for a lateral cortex fracture (p = 0.0041). However, none of the patients had a non-union 1 year postoperative. A hinge fracture occurred in 30% of patients. Hinge fractures with Takeuchi grades I and II increased the gap healing time compared to no fracture (p = 0.0069 and p = 0.0002, respectively), but only 1.2% of patients with hinge fracture had a clinical relevant loss of correction ≥ 3 mm. No implant failures were found.

CONCLUSIONS

Open wedge HTO using the PEEKPower HTO plate for patients with medial osteoarthritis of the knee in combination with tibial varus deformity leads to excellent bony consolidation also in cases with a hinge fracture, a gap size > 12 mm as well as for severely obese patients.

The effect of medial open wedge high tibial osteotomy on the patellofemoral joint: comparative analysis according to the preexisting cartilage status

BACKGROUND

Although it has been known that medial open wedge high tibial osteotomy (MOWHTO) would adversely affect the patellofemoral joint, no previous study examined the surgical outcome of MOWHTO according to the preexisting cartilage status of the patellofemoral joint. The aim of this study was to investigate the effect of MOWHTO on the patellofemoral joint with regard to objective and subjective aspects according to the preexisting cartilage status.

METHODS

Ninety-two patients who underwent MOWHTO and a following second-look arthroscopic assessment were included in this study. The patients were divided into two groups according to the preexisting cartilage status of the patellofemoral joint: group 1 (International Cartilage Repair Society [ICRS] grade 2 or 3) and group 2 (ICRS grade 0 or 1). Comparative analysis was performed regarding clinical scores, radiographic parameters, and arthroscopic measurements between the two groups.

RESULTS

Clinical outcomes showed overall improvement from baseline to the time of second-look operation, with no significant difference between the two groups at each time point. There were no significant differences in radiographic parameters between the two groups. Radiographic grade of patellofemoral osteoarthritis in both groups showed a tendency to progress, without statistical significance. In arthroscopic assessment, the size of the cartilage lesion on the patellofemoral joint increased with time in both groups (P = 0.003), but the degree of change over time between the two groups was not statistically significant. Consistently, there was no significant difference in the frequency of progression of cartilage lesion grade in the patellofemoral joint between the two groups.

CONCLUSIONS

MOWHTO would contribute to osteoarthritis progression of the patellofemoral joint regardless of the preexisting cartilage status, without an association with clinical outcomes in short-term follow-up.

Large opening gaps, unstable hinge fractures, and osteotomy line below the safe zone cause delayed bone healing after open-wedge high tibial osteotomy

PURPOSE

To evaluate bone formation in the osteotomy gap after open-wedge high tibial osteotomy (OWHTO), including after plate removal, and to investigate risk factors for delayed bone healing.

METHODS

Ninety-three patients (102 knees) who underwent OWHTO without bone grafting were enrolled. The osteotomy gap was divided into the lateral hinge and the four zones on anteroposterior radiographs, and we defined the zone in which trabecular bone continuity could be observed as gap filling. Bone formation in the osteotomy gap was evaluated according to this definition at 3, 6, and 12 months postoperatively; at plate removal; and at the final follow-up (mean, 62.3 ± 30.2 months). We also investigated the risk factors for delayed bone healing.

RESULTS

The lateral hinge united at 3 months postoperatively in 92 knees (90.2%). At 1 year postoperatively, 98 knees (96.1%) reached zone 1 and 92 knees (90.2%) reached zone 2. At plate removal, gap filling reached zone 2 in all cases and progressed further without loss of correction after plate removal. Opening width over 13.0 mm [odds ratio (OR): 1.61, P = 0.02], Takeuchi's classification type II lateral hinge fracture (OR: 20.4, P < 0.01), and osteotomy line below the safe zone (OR: 8.98, P < 0.01) significantly delayed bone formation after OWHTO.

CONCLUSIONS

Gap filling progressed from lateral to medial after OWHTO without bone grafting and progressed further after plate removal. Large opening gaps, unstable hinge fractures, and osteotomy line below the safe zone cause delayed bone healing after OWHTO.

Editorial Commentary: Lateral Hinge Fracture in High Tibial Osteotomy: Risk or Annex?

The basic aim of the medial opening wedge high tibial osteotomy is to use the elasticity of the lateral cortex as a biomechanical stabilizer, whereas the medial opening gap is maintained by a locking plate. This surgical construct tolerates early weight bearing, free range of knee motion, and sufficient bone healing for an acceptable time. We always perform a biplanar osteotomy, which reduces risk of fracture and improves healing potential owing to more bony contact area. We take some time opening the wedge owing to the elasticity of the lateral cortex. Careless manipulation can harm your hinge! Preoperative planning regarding corrective and postoperative expected joint line angles is key. If the gap is more than 10 mm, we use autologous bone graft or substitute. Partial weight bearing is indicated for 6 weeks to reduce fracture risk. When indicated, we perform double osteotomies, at the distal femur and proximal tibia, to perfectly achieve postoperative joint angles within the intended mechanical axis goal. Fractures of the lateral hinge occur in up to 30% of cases, whereas our nonunion rate is 5.4%.

Predictive Factors for and Detection of Lateral Hinge Fractures Following Open Wedge High Tibial Osteotomy: Plain Radiography Versus Computed Tomography

PURPOSE

To compare the accuracy of plain radiography and computed tomography (CT) in detecting lateral hinge fractures and to identify predictive factors of the lateral hinge fractures after open wedge high tibial osteotomy (HTO).

METHODS

This study included patients who underwent isolated primary open wedge HTO for medial compartment degenerative arthritis from 2015 to 2016 and were evaluated by postoperative CT scans and followed for a minimum of 1 year. This study involved 48 patients (48 knees) undergoing open wedge HTO for primary medial osteoarthritis. Lateral hinge fractures were evaluated on immediate plain radiographs and CT scans according to the Takeuchi classification. Predictive factors of plain radiograph-based hinge fracture and CT-based hinge fracture were investigated.

RESULTS

The detection rate of lateral hinge fracture was significantly higher on CT scans than on plain radiographs (50% vs 14.6%; P < .001). Seven knees (14.6%) showed lateral hinge fractures on postoperative plain radiographs, including 6 with type I and 1 with type III fractures; 24 (50.0%) showed lateral hinge fractures on postoperative CT scans, including 20 with type I, 2 with type II, and 2 with type III fractures. CT scans detected 14 type I, 2 type II, and 1 type III hinge fractures not detected by plain radiographs. The medial opening gap width was the only predictor of lateral hinge fracture on CT scans (adjusted odds ratio, 1.565; P =.034).

CONCLUSIONS

The incidence of lateral hinge fracture of the knee after open wedge HTO was higher on CT scans than on plain radiographs. The medial opening gap width was the only predictor of lateral hinge fractures, suggesting a need for care when spreading the gap to avoid lateral hinge fractures.

LEVEL OF EVIDENCE

Level III, cross-sectional study.

Numerical comparative study of five currently used implants for high tibial osteotomy: realistic loading including muscle forces versus simplified experimental loading

Background

Many different fixation devices are used to maintain the correction angle after medial open wedge high tibial osteotomy (MOWHTO). Each device must provide at least sufficient mechanical stability to avoid loss of correction and unwanted fracture of the contralateral cortex until the bone heals. In the present study, the mechanical stability of following different implants was compared: the TomoFix small stature (sm), the TomoFix standard (std), the Contour Lock, the iBalance and the second generation PEEKPower. Simplified loading, usually consisting of a vertical load applied to the tibia plateau, is used for experimental testing of fixation devices and also in numerical studies. Therefore, this study additionally compared this simplified experimental loading with a more realistic loading that includes the muscle forces.

Method

Two types of finite element models, according to the considered loading, were created. The first type numerically simulated the static tests of MOWHTO implants performed in a previous experimental biomechanical study, by applying a vertical compressive load perpendicularly to the plateau of the osteotomized tibia. The second type included muscle forces in finite element models of the lower limb with osteotomized tibiae and simulated the stance phase of normal gait. Section forces in the models were determined and compared. Stresses in the implants and contralateral cortex, and micromovements of the osteotomy wedge, were calculated.

Results

For both loading types, the stresses in the implants were lower than the threshold values defined by the material strength. The stresses in the lateral cortex were smaller than the ultimate tensile strength of the cortical bone. The implants iBalance and Contour Lock allowed the smallest micromovements of the wedge, while the PEEKPower allowed the highest. There was a correlation between the micromovements of the wedge, obtained for the simplified loading of the tibia, and the more realistic loading of the lower limb at 15% of the gait cycle (Pearson’s value r = 0.982).

Conclusions

An axial compressive load applied perpendicularly to the tibia plateau, with a magnitude equal to the first peak value of the knee joint contact forces, corresponds quite well to a realistic loading of the tibia during the stance phase of normal gait (at 15% of the gait cycle and a knee flexion of about 22 degrees). However, this magnitude of the knee joint contact forces overloads the tibia compared to more realistic calculations, where the muscle forces are considered. The iBalance and Contour Lock implants provide higher rigidity to the bone-implant constructs compared to the TomoFix and the PEEKPower plates.

Static and fatigue strength of a novel anatomically contoured implant compared to five current open-wedge high tibial osteotomy plates

Background

The purpose of the present study was to compare the mechanical static and fatigue strength of the size 2 osteotomy plate “Activmotion” with the following five other common implants for the treatment of medial knee joint osteoarthritis: the TomoFix small stature, the TomoFix standard, the Contour Lock, the iBalance and the second generation PEEKPower.

Methods

Six fourth-generation tibial bone composites underwent a medial open-wedge high tibial osteotomy (HTO), according to standard techniques, using size 2 Activmotion osteotomy plates. All bone-implant constructs were subjected to static compression load to failure and load-controlled cyclic fatigue failure testing, according to a previously defined testing protocol. The mechanical stability was investigated by considering different criteria and parameters: maximum forces, the maximum number of loading cycles, stiffness, the permanent plastic deformation of the specimens during the cyclic fatigue tests, and the maximum displacement range in the hysteresis loops of the cyclic loading responses.

Results

In each test, all bone-implant constructs with the size 2 Activmotion plate failed with a fracture of the lateral cortex, like with the other five previously tested implants. For the static compression tests the failure occurred in each tested implant above the physiological loading of slow walking (> 2400 N). The load at failure for the Activmotion group was the highest (8200 N). In terms of maximum load and number of cycles performed prior to failure, the size 2 Activmotion plate showed higher results than all the other tested implants except the ContourLock plate. The iBalance implant offered the highest stiffness (3.1 kN/mm) for static loading on the lateral side, while the size 2 Activmotion showed the highest stiffness (4.8 kN/mm) in cyclic loading.

Conclusions

Overall, regarding all of the analysed strength parameters, the size 2 Activmotion plate provided equivalent or higher mechanical stability compared to the previously tested implant. Implants with a metaphyseal slope adapted to the tibia anatomy, and positioned more anteriorly on the proximal medial side of the tibia, should provide good mechanical stability.

Posteromedially placed plates with anterior staple reinforcement are not successful in decreasing tibial slope in opening-wedge proximal tibial osteotomy

PURPOSE

To document the effectiveness of a novel technique to decrease tibial slope in patients who underwent a proximal opening-wedge osteotomy with an anteriorly sloped plate placed in a posteromedial position. The hypothesis was that posteromedial placement of an anteriorly sloped osteotomy plate with an adjunctive anterior bone staple on the tibia would decrease, and maintain, the tibial slope correction at a minimum of 6 months following the osteotomy.

METHODS

All patients who underwent biplanar medial opening-wedge proximal tibial osteotomy with anterior staple augmentation to decrease sagittal plane tibial slope were included, and data were collected prospectively and reviewed retrospectively. Indications for decreasing tibial slope included medial compartment osteoarthritis with at least one of the following: ACL deficiency, posterior meniscus deficiency, or flexion contracture. Preoperative, immediate postoperative, and 6-month postoperative radiographs were reviewed.

RESULTS

Twenty-one patients (14 males and 7 females) were included in the study with a mean age of 36.5 years. Intrarater and interrater reliability of slope measurements were excellent at all time points (ICC ≥ 0.94, ICC ≥ 0.85). The osteotomy resulted in an average tibial slope decrease of 0.8 from preoperative (n.s.). At 6-month postoperative, average slope was not significantly different from time-zero postoperative slope (mean = +0.2°).

CONCLUSIONS

The most important finding of this study was that posteromedial placement of an anteriorly angled osteotomy plate augmented with an anterior staple during a biplanar medial opening-wedge proximal tibial osteotomy did not decrease sagittal plane tibial slope. Whether a staple was effective in maintaining tibial slope from time zero to 6 months postoperatively was unable to be assessed due to no significant change in tibial slope from the preoperative postoperative states. The results of this study note that current osteotomy plate designs and surgical techniques are not effective in decreasing sagittal plane tibial slope.

LEVEL OF EVIDENCE

IV.

High Rates of Return to Sports Activities and Work After Osteotomies Around the Knee: A Systematic Review and Meta-Analysis

BACKGROUND

Knee osteotomies are proven treatment options, especially in younger patients with unicompartmental knee osteoarthritis, for certain cases of chronic knee instability, or as concomitant treatment for meniscal repair or transplantation surgery. Presumably, these patients wish to stay active. Data on whether these patients return to sport (RTS) activities and return to work (RTW) are scarce.

OBJECTIVES

Our aim was to systematically review (1) the extent to which patients can RTS and RTW after knee osteotomy and (2) the time to RTS and RTW.

METHODS

We systematically searched the MEDLINE and Embase databases. Two authors screened and extracted data, including patient demographics, surgical technique, pre- and postoperative sports and work activities, and confounding factors. Two authors assessed methodological quality. Data on pre- and postoperative participation in sports and work were pooled.

RESULTS

We included 26 studies, involving 1321 patients (69% male). Mean age varied between 27 and 62 years, and mean follow-up was 4.8 years. The overall risk of bias was low in seven studies, moderate in ten studies, and high in nine studies. RTS was reported in 18 studies and mean RTS was 85%. Reported RTS in studies with a low risk of bias was 82%. No studies reported time to RTS. RTW was reported in 14 studies; mean RTW was 85%. Reported RTW in studies with a low risk of bias was 80%. Time to RTW varied from 10 to 22 weeks. Lastly, only 15 studies adjusted for confounders.

CONCLUSION

Eight out of ten patients returned to sport and work after knee osteotomy. No data were available on time to RTS. A trend toward performing lower-impact sports was observed. Time to RTW varied from 10 to 22 weeks, and almost all patients returned to the same or a higher workload.

Patellofemoral Osteoarthritis Progression and Alignment Changes after Open-Wedge High Tibial Osteotomy Do Not Affect Clinical Outcomes at Mid-term Follow-up

PURPOSE

To evaluate the clinical and radiological outcomes of open-wedge high tibial osteotomy (OWHTO) with respect to the patellofemoral joint and to assess whether patellofemoral osteoarthritis (OA) progression and alignment changes after OWHTO affect clinical outcomes.

METHODS

Inclusion criteria were consecutive patients who underwent OWHTO from March 2005 to September 2013. Exclusion criteria were loss to follow-up within 2 years and absence of second-look arthroscopy findings at the time of plate removal. The clinical parameters, including anterior knee pain while climbing stairs, Japanese Orthopedic Association score, and Oxford Knee Score, were evaluated. Radiological outcomes, including weight-bearing line ratio, modified Blackburne-Peel ratio, posterior tibial slope, tilting angle, lateral shift ratio, and patellofemoral OA (Kellgren-Lawrence grade), were evaluated preoperatively and at the final follow-up. Cartilage status (International Cartilage Repair Society grade) was evaluated at the initial HTO and at plate removal.

RESULTS

Fifty-three patients (60 knees) were included in this study. The mean follow-up was 58.2 ± 22.4 months. Two knees (3%) presented with mild anterior knee pain after OWHTO. The mean Japanese Orthopedic Association score (66.9 ± 11.2 to 91.2 ± 9.7) significantly improved (P < .001), and the mean Oxford Knee Score at the final follow-up was 42.0 ± 5.3. The mean modified Blackburne-Peel ratio (0.9 ± 0.1 to 0.7 ± 0.1, P < .001) and tilting angle (6.8 ± 3.7 to 5.6 ± 3.4, P = .033) significantly decreased after OWHTO, whereas no significant changes in posterior tibial slope (P = .511) and lateral shift ratio (P = .522) were observed. Radiologically, patellofemoral OA had progressed in 15 knees (27%), and arthroscopically patellofemoral cartilage degeneration had progressed in 27 knees (45%). However, there was no significant correlation between changes in patellofemoral alignment and clinical outcomes.

CONCLUSIONS

Changes in patellofemoral alignment and patellofemoral OA progression did not affect the clinical outcomes of OWHTO at mid-term follow-up.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

[​Biomechanics of new implants for HTO]

Biomechanical characteristics of 5 tibial osteotomy plates for the treatment of medial knee joint osteoarthritis were examined. Fourth-generation tibial bone composites underwent a medial open-wedge high tibial osteotomy, using TomoFix™ standard, PEEKPower®, ContourLock®, TomoFix™ small stature plates, and iBalance® implants. Static compression load to failure and load-controlled cyclic fatigue failure tests were performed. All plates had sufficient stability up to 2400 N in the static compression load to failure tests. Screw breakage in the iBalance® group and opposite cortex fractures in all constructs occurred at lower loading conditions. The highest fatigue strength in terms of maximal load and number of cycles performed prior to failure was observed for the ContourLock® group followed by the iBalance® implants, the TomoFix™ standard and small stature plates. PEEKPower® had the lowest fatigue strength. All plates showed sufficient stability under static loading. Compared to the TomoFix™ and the PEEKPower® plates, the ContourLock® plate and iBalance® implant showed a higher mechanical fatigue strength during cyclic fatigue testing, suggesting that both mechanical static and fatigue strength increase with a wider proximal T‑shaped plate design together with diverging proximal screws. Mechanical strength of the bone-implant constructs decreases with a narrow T‑shaped proximal end design and converging proximal screws (TomoFix™) or a short vertical plate design (PEEKPower®). Published results indicate high fusion rates and good clinical results with the TomoFix™ plate, which is contrary to our findings. A certain amount of interfragmentary motion rather than high mechanical strength and stiffness seem to be important for bone healing which is outside the scope of this paper.

Sagittal osteotomy inclination in medial open-wedge high tibial osteotomy

PURPOSE

Unlike postoperative changes in posterior tibial slope after medial open-wedge high tibial osteotomy, sagittal osteotomy inclination has not been examined. It has been recommended that the osteotomy line in the sagittal plane be parallel to the medial posterior tibial slope. The purpose of this study was to determine the frequency of parallel osteotomy in medial open-wedge high tibial osteotomy.

METHODS

To determine the sagittal osteotomy inclination, the angle between the medial joint line and the osteotomy line was measured in the lateral radiograph. A positive angle value indicates that the osteotomy is anteriorly inclined relative to the medial posterior tibial slope. Correlation between the sagittal osteotomy inclination and posterior tibial slope was also evaluated.

RESULTS

The mean sagittal osteotomy inclination was 15.1 ± 7.5°. The majority 87.1 % of knees showed an anterior-inclined osteotomy. There was a significantly positive correlation between the postoperative posterior tibial slope and the sagittal osteotomy inclination (r, 0.33; 95 % confidence interval (CI) 0.19-0.46; P < 0.001). The postoperative change in posterior tibial slope also showed a significantly positive correlation with the sagittal osteotomy inclination (r, 0.35; 95 % CI 0.21-0.47; P < 0.001).

CONCLUSION

Although parallel osteotomy in the sagittal plane relative to the medial joint line was planned, only 12.9 % of cases achieved osteotomy parallel to the medial posterior tibial slope in the sagittal plane. Because of high rate of the anterior-inclined osteotomy and their correlations with posterior tibial slope, surgeons should make all efforts to perform parallel osteotomy relative to medial posterior tibial slope.

LEVEL OF EVIDENCE

IV.

Health-related quality of life after open-wedge high tibial osteotomy

PURPOSE

(1) To monitor longitudinal changes in health-related quality of life (HRQOL), pain, knee function, and return to work (RtW) following high tibial osteotomy (HTO) for medial compartment osteoarthritis (OA), and (2) to investigate the influences of psychopathological comorbidities on preoperative impairment and post-operative course.

METHODS

Sixty-four patients were prospectively followed for 24 months after HTO to determine HRQOL, pain, functional outcome, and RtW. Psychopathological comorbidities (e.g. depression) were determined preoperatively. Patients with no psychological distress (ND) were compared to patients with psychological distress (PD) in order to investigate the influence of psychopathological comorbidities on outcome.

RESULTS

There was a significant increase in HRQOL and decrease in pain from 6 month follow-up on. Functional outcomes increased significantly from 12 month follow-up on. In general, there was a steady state of outcomes from 6- to 12-month follow-up on. At final follow-up, 90 % returned to their previous occupation without limitations. Mental component summary (MCS) and functional outcome showed a positive correlation with RtW, while depression had a negative one. A significantly inferior outcome of group PD versus ND was observed at baseline and early follow-up. RtW was significantly prolonged in group PD (8.9 ± 7.6 vs. 3.9 ± 3 months; p < 0.001). At final follow-up, both groups presented with comparable outcomes.

CONCLUSION

HTO for medial compartment OA significantly improves HRQOL, pain, and knee function. Time to RtW is high and critically depends on PD. Further, extend of preoperative impairments, an initially inferior course, and inferior MCS outcome was influenced by PD. However, otherwise no significant differences were observed between groups PD and ND at final follow-up.

LEVEL OF EVIDENCE

Prospective case series, II.

Comparison between two angular stable locking plates for medial opening-wedge high tibial osteotomy: Decisive wedge locking plate versus TomoFix™

BACKGROUND

An adequate stable fixation implant should be used for medial opening-wedge high tibial osteotomy (MOWHTO) to promote rapid bone healing without complications. This study compared the radiographic and clinical outcomes as well as plate-specific complications between two angular stable locking plates in patients following MOWHTO.

METHOD

This prospective study involved 97 patients (50 with DWL^®, group I; 47 with TomoFix™, group II) undergoing MOWHTO for primary medial compartment osteoarthritis between 2010 and 2013. Clinical and radiographic evaluations were performed by using the HSS and WOMAC scores, and calculating mechanical femorotibial angle (mFTA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), and posterior tibial slope (PTS) on radiographs both preoperatively and after 3 years.

RESULTS

A statistically significant difference was observed for the MPTA at the last follow-up between the two groups (P = 0.033). Additionally, the last follow-up MPTA of group I was associated with the osteotomy technique (P = 0.004) and preoperative JLCA (P = 0.034) whereas the last follow-up MPTA of group II was associated with gender (P = 0.001) and BMI (P = 0.008). Furthermore, the results showed that group I had a higher rate of non-union (4%) compared to that in group II (0%).

CONCLUSION

Both locking plates are useful tools in the treatment of medial compartment knee osteoarthritis with varus deformity in young, active patients. However, under special consideration of the complication we found in present study, the TomoFix™ seems to be a better alternative in using the MOWHTO for highly demanding patients.