Preoperative tibiofemoral angle predicts survival of proximal tibia osteotomy

High survivorship rate and good clinical outcomes after high tibial osteotomy in patients with radiological advanced medial knee osteoarthritis: a systematic review

INTRODUCTION

The role of valgus producing high tibial osteotomy (HTO) for the treatment of advanced knee osteoarthritis (OA) is still controversial. The aim of the current systematic review was to assess survivorship and patient-reported outcomes (PROMs) of high tibial osteotomy in patients with radiological advanced medial knee OA.

METHODS

A systematic search of PubMed, Cochrane and EMBASE database was performed in July 2023 in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines. Inclusion and exclusion criteria were applied to identify studies investigating the survivorship rate and PROMs of valgus-producing high tibial osteotomy in patients with advanced knee OA at x-ray assessment in the medial compartment at minimum-two-years follow up. Advanced radiological OA was defined as Kellgren Lawrence (K-L) ≥ 3 or Ahlbäch ≥ 2. Survivorship was defined as percentage of patients free of total knee arthroplasty (TKA) at follow-up. Clinical interpretation of provided PROMs were performed according to minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) target values reported in literature. Survivorship data and PROMs scores were extracted, and studies were stratified based on selected study features. The quality of included studies was assessed with modified Coleman score.

RESULTS

A total of 18 studies, totalling 1296 knees with a mean age between 46.9 and 67 years old, were included. Average survivorship was of 74.6% (range 60 - 98.1%) at 10-years follow up. The subjective scoring systems showed good results according to MCID and PASS, and postoperative improvements were partially maintained until final follow-up.

CONCLUSION

HTO is worth considering as treatment choice even in patients affected by radiological advanced medial knee osteoarthritis. Long term survivorship and good patient reported clinical outcomes could be expected in this population.

LEVEL OF EVIDENCE

IV; systematic review of level III-IV studies.

Preoperative overweight and obesity do not cause inferior outcomes following open-wedge high tibial osteotomy: A retrospective cohort study of 123 patients

Open-wedge high tibial osteotomy (OWHTO) is effective in treating medial compartment osteoarthritis. The association between body mass index (BMI) and outcomes following OWHTO is being debated. This study compared radiographic and clinical outcomes between patients with preoperative overweight, obesity, and normal BMI following OWHTO for medial compartment osteoarthritis. In total, 123 patients (123 knees) who underwent OWHTO for medial compartment osteoarthritis were enrolled and were divided into normal-BMI (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), and obese (>30 kg/m2) groups based on body mass index. The numeric rating scale for pain, mechanical tibiofemoral angle (mTFA), tibia tilting angle (TTA), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for function were evaluated preoperatively and at postoperative follow-ups. The improvements of clinical and radiological outcomes in normal-BMI, overweight, and obese groups were not significantly different. The incidence of soft tissue irritation, wound infection, nonunion, and conversion to total knee arthroplasty were not significantly different between groups.The clinical and radiological outcomes in patients with preoperative overweight, obesity, and normal-BMI were not significantly different. Preoperative overweight and obesity thus has no effect on outcomes following OWHTO during the two years follow-up period. These findings cannot be generalized to patients with morbid obesity.

The Ability to Achieve a Specific Target Angle on Weightbearing Radiographs After Valgus High Tibial Osteotomy for Medial Knee Arthritis Is Not Predictable

Purpose

Standing radiographs are commonly used to plan angular correction in valgus tibial osteotomy for varus gonarthrosis. Most clinical studies have reported postoperative alignment as overall averages or means. The purpose of this study was to compare the preoperatively planned angle of correction measured on weight-bearing radiographs to the follow-up angle measured on weightbearing radiographs in individual patients 6 weeks after surgery and to analyze factors that could potentially affect achieving the planned degree of surgical correction. Our objective was to analyze factors potentially affecting the accuracy and ability to achieve the preoperatively planned correction angle (the target angle) in the individual patient.

Methods

We studied 35 tibial osteotomies (13 Coventry closing wedge osteotomies and 22 Maquet barrel vault osteotomies) performed for varus gonarthrosis between 1981 and 2019 to determine how accurately the target angle, based on preoperative standing weight-bearing radiographs, was achieved according to the postoperative radiographs in each individual. We reviewed 35 knees in 34 patients who had complete pre- and postoperative radiographs for review.

Results

Overall, only 14 of 35 (40%) of the patients were corrected to within ± 2° of the planned target angle. Valgus tibial osteotomy based on preoperative weightbearing radiographs is unpredictable in its ability to achieve the target angle on postoperative weightbearing radiographs when using either the Coventry or the Maquet surgical technique. The tendency was to undercorrect with either of the techniques. Larger (greater than 10°) preoperative varus alignment did not make it more difficult to achieve the target angle. Male or female sex and body mass index had no effect on the ability to achieve the target angle.

Conclusions

Valgus tibial osteotomy planning based on preoperative weightbearing is unpredictable in its ability to achieve the target angle on postoperative weightbearing radiographs. Overall, only 40% of our patients were corrected to within ± 2° of the planned target angle. The tendency was to undercorrect, with either the Coventry or the Maquet technique. Contrary to our hypothesis, larger preoperative varus alignment (greater than 10°) did not make it more difficult to achieve the target angle. The Coventry technique was as accurate as the Maquet technique.

Level of Evidence

Level IV.

The fibular shaft axis and medial cortex of the proximal fibula are reliable landmarks for the mechanical axis of the tibia in patients with knee osteoarthritis

BACKGROUND

This study aimed to evaluate the validity of proximal fibular anatomic landmarks for measuring the coronal tibial mechanical axis in patients with knee osteoarthritis and to investigate individual factors associated with their reliability.

METHODS

A total of 106 knees in 96 patients were retrospectively reviewed. The angles between the tibial mechanical axis and fibular shaft axis (TFA), medial cortex of the proximal fibular shaft (MTA), and lateral cortex of the proximal fibular shaft (LTA) were measured from full-leg standing digital anteroposterior radiographs. An angle within three degrees was considered reliable. The association between the above three angles and individual factors, such as age, sex, body mass index (BMI), and varus-valgus knee malalignment, was determined to investigate individual factors associated with their reliability.

RESULTS

The median TFA, MTA, and LTA were 1.52°, 1.56°, and 2.62°, respectively. The reliability rates of TFA, MTA, and LTA were 73.6% (95% CI: 65.19-81.98%), 82.1% (74.77-89.38%), and 58.5% (49.11-67.87%), respectively. The reliability of TFA and MTA was not associated with individual variables. The reliability of LTA was associated with BMI. Among patients with BMI greater than 25.3 kg/m², LTA was considered reliable in 65.7%; this rate was significantly higher than that among patients with BMI less than 25.3 kg/m².

CONCLUSIONS

The fibular shaft axis and medial cortex of the proximal fibular shaft are reliable landmarks of the mechanical axis of the tibia. However, the reliability of the lateral cortex of the proximal fibular shaft is less satisfactory, especially in patients with BMI less than 25.3 kg/m².

What Determines the Success of Closed-Wedge High Tibial Osteotomy: Severity of Malalignment, Obesity, Follow-up Period, or Age?

Objectives:

High tibial osteotomy (HTO) is a well-established procedure for the treatment of medial knee osteoarthritis originating from malalignment of the lower extremity. The current study was designed to evaluate the clinical and radiographic results of closed-wedge HTO for the treatment of medial knee osteoarthritis and to reveal factors affecting the outcome.

Methods:

A retrospective study was conducted with 138 patients who were operated on for medial knee osteoarthritis between 2000 and 2007 using closed-wedge HTO. Preoperative and follow-up physical examination findings, body mass index (BMI) values, and Hospital for Special Surgery (HSS) and Lysholm knee scores were reviewed. Radiographic evaluation included measurement of the mechanical axis preoperatively and the most recent follow-up orthoroentgenograms. The follow-up knee scores were evaluated according to preoperative mechanical axis, obesity, age, follow-up period, and gender of the patient. The mechanical axis measurement was assessed based on obesity, age, and follow-up period.

Results:

The mean preoperative and latest follow-up mechanical axis was 4.92^o±4.24^o varus and 3.43^o±3.74^o valgus, respectively (p=0.0001). Improvement in the Lysholm (p=0.0001) and HSS (p=0.0001) knee scores was significant. The preoperative mechanical axis, obesity, follow-up period, and gender had no negative effect on the follow-up knee scores, whereas a preoperative age over 50 years had a negative effect on the follow-up knee score. Obesity and the length of the postoperative follow-up period did not have a negative effect on the postoperative mechanical axis, whereas a preoperative age over 50 had a negative effect on the postoperative mechanical axis.

Conclusion:

The results of this study suggest that medial knee osteoarthritis may be treated successfully with closed-wedge HTO. The analysis indicated that factors such as obesity, the degree of preoperative deformity, and gender do not adversely affect the success of treatment. However, a preoperative age over 50 adversely affected the outcome.

Factors associated with discrepancies between preoperatively planned and postoperative alignments in patients undergoing closed-wedge high tibial osteotomy

BACKGROUND

To evaluate the difference between preoperative plan and postoperative alignment after closed-wedge HTO and determine factors associated with difference.

METHODS

This retrospective cohort study included 165 cases with closed-wedge HTO. The following radiographic parameters were measured: mechanical tibiofemoral angle (mTFA), mechanical medial proximal tibial angle (MPTA), joint line convergence angle, mediolateral joint width discrepancy, Kellgren-Lawrence (K-L) grade, and discrepancy between the correction angle in tibia and correction angle in mTFA. The linear regression analysis was used for the preoperative factors that affect the discrepancy between correction angle in tibia and correction angle in mTFA.

RESULTS

Preoperative and postoperative mTFA was varus 8.3°±3.7 and valgus 3.1°±2.6. The MPTA was varus 6.2°±3.1 preoperatively, valgus 3.7°±3.0 postoperatively. The mediolateral joint width discrepancy was 3.1mm±1.8 preoperatively and 1.8mm±1.4 postoperatively. The discrepancy between correction angle in tibia and correction angle in mTFA was 1.5°±2.3 valgus. By regression analysis, one degree of valgus overcorrection was found to be related with every 2.5° of joint convergence angle (r²=0.396), 2.4mm of mediolateral joint width discrepancy (r²=0.310) and increased one grade of K-L classification (r²=0.107) as preoperative measurement.

CONCLUSIONS

The 1.5° valgus overcorrection of postoperative mTFA was found compared with planned correction angle in tibia. By the equation, every 2.5° of joint convergence angle and 2.4mm of mediolateral joint width discrepancy preoperatively could predict one degree of valgus overcorrection.

Mid-term survival analysis of closed wedge high tibial osteotomy: A comparative study of computer-assisted and conventional techniques

BACKGROUND

The purpose of the present study was to compare the clinical and radiographic results and survival rates between computer-assisted and conventional closing wedge high tibial osteotomies (HTOs).

METHODS

Data from a consecutive cohort comprised of 75 computer-assisted HTOs and 75 conventional HTOs were retrospectively reviewed. The Knee Society knee and function scores, Hospital for Special Surgery (HSS) score and femorotibial angle (FTA) were compared between the two groups. Survival rates were also compared with procedure failure.

RESULTS

The knee and function scores at one year postoperatively were slightly better in the computer-assisted group than those in conventional group (90.1 vs. 86.1) (82.0 vs. 76.0). The HSS scores at one year postoperatively were slightly better for the computer-assisted HTOs than those of conventional HTOs (89.5 vs. 81.8). The inlier of the postoperative FTA was wider in the computer-assisted group than that in the conventional HTO group (88.0% vs. 58.7%), and mean postoperative FTA was greater in the computer-assisted group that in the conventional HTO group (valgus 9.0° vs. valgus 7.6°, p<0.001). The five- and 10-year survival rates were 97.1% and 89.6%, respectively. No difference was detected in nine-year survival rates (p=0.369) between the two groups, although the clinical and radiographic results were better in the computer-assisted group that those in the conventional HTO group.

CONCLUSIONS

Mid-term survival rates did not differ between computer-assisted and conventional HTOs. A comparative analysis of longer-term survival rate is required to demonstrate the long-term benefit of computer-assisted HTO.

LEVEL OF EVIDENCE

III.

Does pelvic width influence patellar tracking? A radiological comparison between sexes

INTRODUCTION

Pelvic width has been believed to affect patellar tracking by influencing the quadriceps angle (Q-angle). Anatomically, the upper arm of the Q-angle does not closely match the orientation of the quadriceps femoris. The pelvis is often considered wider and the Q-angle larger in female than in male individuals. The purpose of this retrospective study was to investigate the accuracy of such an assumption by using a radiologic comparison, which might be more objective.

MATERIALS AND METHODS

One hundred consecutive adult patients (50 men and 50 women) aged 18-30 years with unilateral injury to the lower extremity were studied. Full-length standing X-rays of these patients was used to analyze the relationship between the pelvis and the uninjured lower extremity and compare it between the sexes. The pelvic width was defined as the distance between the centers of the bilateral femoral heads.

RESULTS

The pelvic width did not differ statistically between male and female (P=0.74). The femur length and sum of the lengths of the femur and tibia differed between the sexes (both P<0.001). Normalization of the pelvic width to the femur length or sum of the lengths of the femur and tibia resulted in a significant difference between male and female (P<0.001). The angle formed by the femoral and tibial mechanical axes correlated strongly with the angle formed by the femoral anatomic and tibial mechanical axes (Pearson correlation coefficient=0.89).

DISCUSSION

Pelvic width does not differ with respect to gender. The pelvis may appear relatively wider in women due to the difference in body height. However, this difference may not increase Q-angle. Patellar mal-tracking may stem from other, more critical predisposing factors.

LEVEL OF EVIDENCE

Level IV. Anatomic study.

Boomerang proximal tibial osteotomy for the treatment of severe varus gonarthrosis

PURPOSE

The purpose of the study was to review the results of modified infratubercle displacement osteotomy in patients with severe varus gonarthrosis and to determine the factors influencing outcomes.

METHODS

A total of 177 knees in 133 patients with severe varus gonarthrosis were treated with infratubercle boomerang-shaped osteotomy, stabilised with dual plates. The mean age of the patients was 63.8 years (range 43-80 years), and the mean follow-up period was 61.4 months (range 24 -139 months). The factors associated with clinical and survival outcomes were analysed including age, gender, body mass index (BMI), preoperative and post-operative femorotibial angle and femorotibial angle at one year after surgery.

RESULTS

Using the Knee Society clinical rating system 149 knees or 84.2 % were rated as having good to excellent results and 21 knees or 15.8 % as having fair to poor results. Overall, the mean preoperative knee score of 33.6 points had improved significantly to 80.7 points at the final follow-up (p < 0.001). Using Kaplan-Meier survivorship analysis the five-year survival was 97.1 % with conversion to arthroplasty or second osteotomy as the end point and 89.2 % with a knee score of under 70 points as the end point. The anatomical femorotibial angle at one year after osteotomy had the most significant positive effect on the clinical (p < 0.001) and survival outcomes for all end points (p = 0.002 for conversion to arthroplasty or second osteotomy and p < 0.001 for knee score less than 70 points).

CONCLUSIONS

The boomerang osteotomy can create adequate valgus alignment in severe varus gonarthrosis. The one-year post-operative knee alignment of 11° valgus provided the most satisfactory results and that between six and 15° valgus the longest survival time.

The impact of a high tibial valgus osteotomy and unicondylar medial arthroplasty on the treatment for knee osteoarthritis: a meta-analysis

PURPOSE

Both high tibial valgus osteotomy (HTO) and unicompartmental medial knee arthroplasty (UKA) are established methods for the treatment for moderate stages of OA. This is the first global meta-analysis to compare the long-term effects of both methods regarding survival, outcomes and complications of total arthroplasty.

METHODS

Literature research was performed using established medical databases: MEDLINE (via PubMed), EMBASE (via OVID) and the Cochrane register. Criteria for inclusion were as follows: English or German papers, a clinical trial with a clear description of survival, an outcome evaluation using a well-described knee score and a follow-up >5 years. Statistical analysis was performed using the special meta-analysis software called "Comprehensive Meta Analysis" (version 2.0; Biostat, Englewood, NJ, USA).

RESULTS

Final meta-analysis after the full-text review included 46 studies about valgus HTO and 43 studies about medial UKA. There were no significant differences between valgus HTO and medial UKA in terms of the number of total required replacements. After a 5- to 8-year follow-up, 91.0% of the valgus HTO patients and 91.5% of medial UKA patients did not need a total replacement. This value was 84.4% for valgus HTOs and 86.9% for medial UKAs after a 9- to 12-year follow-up. Mean survival time to TKA was 9.7 years after valgus HTO and 9.2 years after medial UKA. Clinical outcome was significantly better after medial UKA in a 5- to 12-year follow-up. After more than 12 years, results were comparable in both groups. No significant differences were seen in the complication rates.

CONCLUSIONS

This meta-analysis aimed to find the advantages and disadvantages of two established methods for the treatment for medial compartment knee osteoarthritis. Valgus HTO is more appropriate for younger patients who accept a slight decrease in their physical activity. Medial UKA is appropriate for older patients obtaining sufficient pain relief but with reduced physical activity.

LEVEL OF EVIDENCE

II.

Osteotomy around the knee: evolution, principles and results

PURPOSE

This article summarises the history and evolution of osteotomy around the knee, examining the changes in principles, operative technique and results over three distinct periods: Historical (pre 1940), Modern Early Years (1940-2000) and Modern Later Years (2000-Present). We aim to place the technique in historical context and to demonstrate its evolution into a validated procedure with beneficial outcomes whose use can be justified for specific indications.

MATERIALS AND METHODS

A thorough literature review was performed to identify the important steps in the development of osteotomy around the knee.

RESULTS

The indications and surgical technique for knee osteotomy have never been standardised, and historically, the results were unpredictable and at times poor. These factors, combined with the success of knee arthroplasty from the 1980s onward, led to knee osteotomy being regarded as an irrelevant surgical option by many surgeons. Despite its fluctuating reputation, this article demonstrates the reasons for the enduring practice of osteotomy, not least because achieving the appropriate alignment is now recognised as the foundation step when planning any surgical intervention.

CONCLUSIONS

With appropriate patient selection, accurate pre-operative planning, modern surgical fixation techniques and rapid rehabilitation, osteotomy around the knee is now an effective biological treatment for degenerative disease, deformity, knee instability and also as an adjunct to other complex joint surface and meniscal cartilage surgery.

LEVEL OF EVIDENCE

V.

Distal femoral osteotomy for valgus arthritic knees

BACKGROUND

Patients with genu valgum and isolated osteoarthritis of the lateral compartment are candidates for distal femoral varus osteotomy. Opening wedge osteotomy is a precise method to realign the knee axis with good short to midterm results. The aim of this study was to evaluate the outcome of patients who have had opening wedge distal femoral varus osteotomy utilizing the Puddu plate (Arthrex, Naples, FL, USA) fixation.

METHODS

The study included 6 patients (7 knees) followed for an average of 6.5 ± 1.5 years after distal femoral varus osteotomy with Puddu fixation and iliac crest allograft. Clinical outcome was assessed by the Oxford Knee Score and subjective satisfaction rating. Pre- and postoperative radiographs were evaluated for tibiofemoral angle, Insall-Salvati index and Kellgren-Lawrence Grading Scale for osteoarthritis.

RESULTS

The mean age at surgery was 46.7 ± 10.7 years. The mean body mass index at surgery was 29.6 ± 5.6 kg/m(2). Overall at the last follow-up the mean Oxford Knee Score improved from 13.1 ± 8.6 to 26 ± 12.5. The average subjective satisfaction rate at the last follow-up was 6.6 ± 2.8. The measured tibiofemoral angle was corrected by an average of 11.9°. There was no worsening of arthritic changes in comparison to the preoperational radiographs. All radiographs showed full incorporation of the bone grafts, and there were no hardware failures. At the end of this study none of the patients required additional surgery, and none had knee replacement.

CONCLUSIONS

Opening wedge distal femoral varus osteotomy with Puddu plate fixation can be a reliable procedure for the treatment of lateral compartment osteoarthritis of the knee associated with valgus deformity.

Closing-wedge high tibial osteotomy: survival and risk factor analysis at long-term follow up

Background

Closing-wedge high tibial osteotomy (HTO) is successful for the treatment of medial osteoarthritis with varus malalignment. Preoperative risk factors for HTO failure are still controversial. The aim of this study was to elucidate the outcome and assess the influence of risk factors on long term HTO survival.

Methods

199 patients were retrospectively studied with a mean follow-up period of 9.6 years after HTO. HTO failure was defined as the need for conversion to TKA. Survival was analyzed with the Kaplan-Meier method. Knee function was evaluated by the Hospital for Special Surgery (HSS) score. HTO-associated complications were also assessed. Univariate, multivariate, and logistic regression analysis were performed to evaluate the influence of age, gender, BMI, preoperative Kellgren-Lawrence osteoarthritis grade, and varus angle on HTO failure.

Results

39 complications were recorded. Thus far, 36 HTOs were converted to TKA. The survival of HTO was 84% after 9.6 years. Knee function was considered excellent or good in 64% of patients. A significant preoperative risk factor for HTO failure was osteoarthritis, Kellgren-Lawrence grade >2.

Conclusion

HTO provides good clinical results in long-term follow-up. Preoperative osteoarthritis Kellgren-Lawrence grade >2 is a significant predictive risk factor for HTO failure. Results of HTO may be improved by careful patient selection. Complications associated with HTO should not be underestimated.

Varus inclination of the proximal tibia or the distal femur does not influence high tibial osteotomy outcome

We have analysed retrospectively the influence of different sources of knee deformity on failure of closing wedge high tibial valgus osteotomy (HTO). Preoperative frontal plane varus deformities of the lower extremity, distal femur and proximal tibia, and medial convergence of the knee joint line were assessed on a standard whole leg radiograph in 76 patients. Using the logistic regression model, the probability of survival for HTO was 77% (SD 4%) at 10-years follow-up. Varus deformity of the lower extremity (< 175 degrees ), and medial convergence of the knee joint line (> 3 degrees ) were identified as preoperative risk factors for conversion to arthroplasty (P = 0.03 and P = 0.006). We found no evidence that varus inclination of the proximal tibia or distal femur influences long-term survival of HTO.

Survival of closing-wedge high tibial osteotomy: good outcome in men with low-grade osteoarthritis after 10-16 years

BACKGROUND AND PURPOSE

High tibial valgus osteotomy (HTO) is a well-accepted treatment for medial unicompartmental osteoarthritis of the knee with varus alignment in relatively young and active patients. Controversies about the factors affecting survival of HTO still exist. We assessed preoperative risk factors for failure of closing-wedge HTO at long-term follow-up.

PATIENTS AND METHODS

A cohort of 100 patients with a mean age of 49 (24-67) years, who had closing-wedge HTO performed between January 1991 and December 1996, were analyzed retrospectively. A survival analysis was carried out according to the Kaplan-Meier method. Logistic regression analysis was used to assess the association between failure of the osteotomy and known potential preoperative risk factors.

RESULTS

The probability of survival for HTO was 75% (SD 4%) at 10 years with knee replacement as the endpoint. Female sex and osteoarthritis of grade > or = 2 were identified as preoperative risk factors for conversion to arthroplasty 10 years after HTO.

INTERPRETATION

Our findings suggest that ideal candidates for corrective osteotomy are men with symptomatic medial compartmental osteoarthritis of Ahlback grade 1, who, 10 years after surgery, have an almost tenfold lower probability of failure of HTO than women with more advanced osteoarthritis.

Präzise computergestützte Beinachsenkorrektur mit öffnender valgisierender Tibiakopfosteotomie

AIM

This prospective study investigates open-wedge high tibial osteotomy performed with the aid of a kinematic computer-guided navigation system. After the X-ray control the osteotomy was stabilized by internal LCP fixation. The aim of the study was to demonstrate the accuracy of the navigation system and to prove the reliability of the LCP fixation.

METHOD

A total of 39 patients were operated between 2002 and 2003 following this method. The outcomes were evaluated at least 2 years after the surgery clinically and radiologically; 21 females (1 female underwent bilateral osteotomy) and 18 males were included in the study sample.

RESULTS

Prior to the osteotomy, the mean anatomic lateral tibiofemoral angle (aLTFA) was 181.1 degrees . The desired 4 degrees "overcorrection" of valgus (aLTFA 170 degrees) was found on X-rays postoperatively in all cases. The mean correction was 11.1 degrees. The correction achieved was stable during the 2-year follow-up period. The osteotomy healed in all cases after 4 months. The full range of motion remained after the surgery in all cases. All patients were satisfied with their results. The Lysholm score was 55 points before and 82 points after the osteotomy (27 points difference).

CONCLUSION

The computer-assisted open-wedge high tibial osteotomy with tricortical grafts stabilized by LCP fixation gives exact and reproducible results without loss of correction.

Femoral shaft bowing influences the correction angle for high tibial osteotomy

BACKGROUND

The optimal femorotibial angle (FTA) after high tibial osteotomy (HTO) is still controversial. Our hypothesis was that FTA itself may not be reliable because FTA cannot represent the accurate alignment of the whole lower extremity.

METHODS

Non-weight-bearing radiographs of the lower extremities were taken in 100 Japanese subjects with medial osteoarthritic knees, and seven anatomic parameters were assessed. The correction angle by FTA was calculated so that the postoperative FTA was set at 166 degrees (14 degrees valgus). Another correction angle was calculated so that the mechanical axis passed through the lateral one-fourth of the tibial articular surface after HTO. After the correlation between two correction angles was assessed, influences of anatomic parameters on the discrepancy between two correction angles were assessed.

RESULTS

There was a high correlation between two correction angles (R2 = 0.777, P < 0.001). The mechanical axis passed through the lateral one-fourth of the tibial articular surface when the postoperative FTA was set at 166 degrees in 80% of subjects. However, discrepancy between the two correction angles was 3 degrees or larger in 20% of subjects. Femoral shaft bowing and tibial shaft bowing significantly influenced the correction angles. Even though FTA was the same, the femoral head shifted medially in cases with lateral bowing of the femoral shaft, and the correction angle by FTA should be set larger. On the other hand, the correction angle by FTA can be set smaller in knees with medial bowing of the femoral shaft. Tibial shaft bowing also influences the correction angle by FTA.

CONCLUSIONS

The correction angle by FTA for HTO should be calculated taking femoral and/or tibial shaft bowing in the frontal plane into account.

A 12-28-year followup study of closing wedge high tibial osteotomy

Current indications for high tibial osteotomy (HTO) are controversial although several risk factors have been associated with HTO survival. We ascertained the influence of preoperative variables in a consecutive series of patients who had closing wedge HTO at a minimum of 12 year followup (mean 18-year, range 12 to 28 years). Three hundred one of an initial 372 high tibial osteotomies (313 patients) were included (81% followup); 71 knees were eliminated because patients died (30 knees) or were lost to followup (41 knees). The mean age was 42 years (range, 15-76 years), 194 were men and 119 were women. The osteotomy was fixed by a Blount staple and an AO half-tube plate with three screws. Forty-three knees (14%) in 39 patients were revised for progression of osteoarthritis at an average of 102 months. Survival was 85% at 20 years with revision as the endpoint. Knee function was considered satisfactory by 77% of patients. At final followup, 1/2 of the knees showed radiographic signs of medial osteoarthritis. The most important risk factors predicting revision were age greater than 50 years and a preoperative arthritis Ahlback grade of 3 or more.