The value of the intra-operative clinical mechanical axis measurement in open-wedge valgus high tibial osteotomies

Effect of limb alignment correction on medial meniscus extrusion under loading condition in high tibial osteotomy

Background

This study aimed to investigate the effect of high tibial osteotomy (HTO) on medial meniscus extrusion (MME) and the association between the changes in limb alignment and MME under weight-bearing (WB) conditions after HTO.

Methods

We included 17 patients with knee osteoarthritis (OA) who underwent HTO. MME was evaluated using ultrasonography in supine and unipedal standing positions. Knee alignment was evaluated radiographically using WB, whole-leg radiographs with the hip-knee-ankle angle (HKAA), percentage of the mechanical axis (%MA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA). All measurements were performed serially at four time points: preoperative and 3, 6, and 12 months postoperative. Clinical outcomes were assessed by knee injury and osteoarthrosis outcome score (KOOS) and visual analogue scale (VAS) value for pain.

Results

Mean MME in the WB position was significantly greater than that in the supine position in the preoperative condition; however, MME in both supine and WB positions was significantly lowered postoperatively. The ΔMME, difference of MME between supine and WB positions, was significantly lowered postoperatively and maintained for up to 1 year. MME change in the WB position between preop and postoperative conditions was significantly correlated with change in HKAA and %MA at 1 year postoperative. KOOS and VAS score were significantly improved after HTO.

Conclusions

HTO correcting varus alignment can decrease MME in WB position and minimise the change in MME between supine and WB positions. The changes in MME after HTO were correlated with changes in the mechanical alignments.

Clinical and radiological outcomes of medial opening-wedge monoplanar and biplanar high tibial osteotomy using a triangular allograft impaction technique: A retrospective single centre study

PURPOSE

The aim of the study was to research the clinical and radiological outcomes between monoplanar and biplanar medial opening-wedge high tibial osteotomy. We hypothesized that there would be no differences between both techniques when using a triangular allograft impaction technique.

METHODS

A single-centre, observational, retrospective study was conducted on 103 opening-wedge high tibial osteotomy patients from January 2017 to September 2019. Data collection, NRS and KOOS-PS, was performed preoperatively, 3 months and 12 months postoperatively. Radiological assessment (Kellgren-Lawrence, mechanical femoral-tibial angle, posterior tibial slope angle, lateral patellar tilt, patellar height) was performed on standing radiographs.

RESULTS

In total 32 patients were included in the biplanar group and 71 patients in the monoplanar group. NRS and KOOS-PS scores improved significantly (p < 0.001) in time for both groups from baseline to 3 m PO and further to 1 year postoperatively. Our results showed no differences in radiological outcomes such as patellar height, LPT and posterior tibial slope angle. The monoplanar group did have more Takeuchi I and III fractures and a higher mFTA angle without clinical repercussion.

CONCLUSIONS

Using a triangular allograft impaction technique for monoplanar and biplanar medial opening-wedge high tibial osteotomy gives no differences in clinical (NRS and KOOS) and radiological outcomes. Although a difference in Takeuchi fractures was found for monoplanar patients, no additional fixation was necessary, nor did clinical complications occur. We can conclude that triangular allograft impaction technique creates a stable construct and standardizes the healing procedure postoperatively for both monoplanar and biplanar medial opening-wedge high tibial osteotomy.

The position of the lateral tibial spine and the implications for high tibial osteotomy planning

The lateral tibial spine (LTS) is frequently proposed as a correction target in high tibial osteotomy (HTO), although little is known about its exact radiographic position. This study primarily aims to define the position and variance of the LTS. Secondly, this study wants to investigate the relevance of the LTS position on the mechanical tibiofemoral angle (mTFA°) while planning and postoperatively landing the weight-bearing line (WBL) on this landmark. The LTS position was studied on preoperative full-leg standing radiographs (FLSR) and computed tomography (CT) scans in 70 cases. 3D models of the tibia were created in Mimics 23.0 and measurements were conducted in 3-matic 15.0 (Materialise, Leuven®). Next, 100 HTO cases were retrospectively planned with the WBL through the LTS according to Dugdale's method on FLSR. Finally, 55 postoperative FLSR which had the WBL on the LTS (±2%) were assessed for mTFA° outcome. Statistics were conducted in GraphPad 8.0. The LTS was located at 58.3%±1.9 [55-63%] in 2D and 57.3%±2.2 [53-63%] in 3D showing a high correlation (r=0.77 [0.65 to 0.85]). The planned mTFA on the LTS was 181.8°±0.3 (181.3°-182.5°). On postoperative FLSR, the mTFA was 182.2°±0.6 (180.9°-183.1°). The lateral tibial spine is located at 57-58% on the tibial plateau with a 10% maximal variation range. Good agreement was found between 2D and 3D imaging modalities while evaluating its position in the coronal plane. When aiming the WBL through the LTS during valgus-producing HTO, a consistent realignment of 181-183° mTFA can be expected when performing accurate surgery.

Impacted bone allograft personalised by a novel 3D printed customization kit produces high surgical accuracy in medial opening wedge high tibial osteotomy: a pilot study

PURPOSE

Contemporary medial opening wedge high tibial osteotomy (MOWHTO) still seems to struggle with inconsistent accuracy outcomes. Our objective was to assess surgical accuracy and short-term clinical outcomes when using 3D planning and a patient-specific instrumentation (PSI) kit to prepare customized bone allografts.

METHODS

Thirty subjects (age 48y ± 13) were included in a double-center prospective case series. A low-dose CT-scan was performed to generate 3D bone models, a MOWHTO was simulated, and PSI was designed and 3D printed based on the complementary negative of the planned osteotomy gap. Clinical outcome was assessed at two, four, 12 weeks and one year using NRS, KOOS, UCLA activity score, EQ-5D and anchor questions. A linear-mixed model approach was implemented for data analysis.

RESULTS

Preoperative 3D values were 175.0° ± 2.2 mechanical tibiofemoral angle (mTFA), 85.0° ± 3.0 medial proximal tibial angle (MPTA), and 94.1° ± 3.4 medial posterior tibial slope (MPTS). Target planning ranged from slight varus to the lateral tibial spine (slight valgus). Postoperative 3D analysis showed an accuracy of 1.1° ± 0.7 ΔMPTA (p = 0.04) and 1.2° ± 1.2 ΔMPTS (p = 0.11). NRS decreased from baseline 6.1 ± 1.9 to 2.7 ± 1.9 at four weeks (p < 0.001) and 1.7 ± 1.9 at one year (p < 0.001). KOOS increased from 31.4 ± 17.6 to 50.6 ± 20.6 at 12 weeks (p < 0.001) and to 71.8 ± 15.6 at one year (p < 0.001).

CONCLUSION

The study suggests that 3D printed instrumentation to personalize structural bone allograft is a viable alternative method in MOWHTO that has the benefit of optimizing surgical accuracy while providing early and consistent pain relief after surgery.

Influence of Medial Osteotomy Height and Hinge Position in Open Wedge High Tibial Osteotomy: A Simulation Study

(1) Background: In treating medial unicompartmental gonarthrosis, medial open wedge high tibial osteotomy (mOWHTO) reduces pain and is intended to delay a possible indication for joint replacement by relieving the affected compartment. This study aimed to investigate the influence of the osteotomy height with different hinge points in HTO in genu varum on the leg axis. (2) Methods: Fifty-five patients with varus lower leg alignment obtained full-weight bearing long-leg radiographs were analyzed. Different simulations were performed: Osteotomy height was selected at 3 and 4 cm distal to the tibial articular surface, and the hinge points were selected at 0.5 cm, 1 cm, and 1.5 cm medial to the fibular head, respectively. The target of each correction was 55% of the tibial plateau measured from the medial. Then, the width of the opening wedge was measured. Intraobserver and interobserver reliability were calculated. (3) Results: Statistically significant differences in wedge width were seen at an osteotomy height of 3 cm below the tibial plateau when the distance of the hinge from the fibular head was 0.5 cm to 1.5 cm (3 cm and 0.5 cm: 8.9 +/− 3.88 vs. 3 cm and 1.5 cm: 11.6 +/− 4.39 p = 0.012). Statistically significant differences were also found concerning the wedge width between the distances 0.5 to 1.5 cm from the fibular head at the osteotomy height of 4 cm below the tibial plateau. (4 cm and 0.5 cm: 9.0 +/− 3.76 vs. 4 cm and 1.5 cm: 11.4 +/− 4.27 p = 0.026). (4) Conclusion: A change of the lateral hinge position of 1 cm results in a change in wedge width of approximately 2 mm. If hinge positions are chosen differently in preoperative planning and intraoperatively, the result can lead to over- or under-correction.

Is the lateral tibial spine a reliable landmark for planning tibial or femoral valgus osteotomies?

INTRODUCTION

A valgus osteotomy around the knee is a conservative procedure performed to unload the medial tibiofemoral compartment. However, the optimal postoperative alignment target remains controversial. Many studies have applied a "Fujisawa point" at 62.5%. The results of recent studies suggest decreasing the range of the mechanical axis target correction to 50-55%. The primary purpose of this study was to define the mean position of the lateral tibial spine in healthy patients from a reproducible 3-dimensional (3D) analysis. The study hypothesis was that the apex of the lateral tibial spine was a reliable and reproducible landmark for planning valgus osteotomies and preventing overcorrections.

MATERIALS AND METHODS

The study included 1140 patients: 560 women and 580 men, with a mean age of 61.7±16.5 years (18-98) and a mean body mass index (BMI) of 24.9±4.9kg/m² (13.3-54.6). This analysis was done with the Stryker Orthopaedics Modeling and Analytics (SOMA) system which uses a database of computed tomography (CT) scans and 3D bone models. A statistical assessment was performed to determine the mean position of the lateral tibial spine. These measurements were then compared according to ethnicity, sex, age, BMI, knee side (right and left) and the overall mechanical axis of the leg.

RESULTS

The mean tibial plateau width was 72.9±5.7mm (59.1-91.1). The mean position of the lateral tibial spine was 53.6±1.1% (48.9-57.2). The mean position of the medial tibial spine was 48.4±2.5% (43.6-56.1) while the center of the tibial spines was 51.0±1.5% (46.4-56.1). Africans had a significantly more lateral mean tibial spine position than Asians (54.7% vs. 53.3%, p=0.001), Caucasians (54.7% vs. 53.7%, p=0.002) and Middle Easterners (54.7% vs. 53.6%, p=0.034).

CONCLUSION

The lateral tibial spine is a simple and reproducible bony landmark. This landmark can be used when planning valgus osteotomies aiming for a "Fujisawa point" at 54%.

LEVEL OF EVIDENCE

IV.

HKA Angle-A Reliable Planning Parameter for High Tibial Osteotomy: A Theoretical Analysis Using Standing Whole-Leg Radiographs

High tibial osteotomy (HTO) is a recognized treatment for early-stage medial compartment knee osteoarthritis. Preoperative planning with standing whole-leg radiographs (WLRs) is essential for ensuring optimal postoperative alignment. The primary purpose of this study is to investigate the theoretical accuracy of the wedge opening required for two different preoperative planning parameters in open-wedge HTO. The second purpose is to theoretically determine which parameter is superior. Preoperative planning for HTO was performed with standing WLRs for 39 knees with isolated medial osteoarthritis. The Miniaci preoperative planning method was applied to correct the hip-knee-ankle (HKA) angle to 3to 6 degrees of valgus and the weight-bearing line (WBL) percentage within 60 to 70% of the width of the tibial plateau. To ensure that the HKA angle was between 3 and 6 degrees of valgus, the required accuracy window for the Miniaci angle was 3.25 ± 0.03 degrees (range, 3.20-3.30°). To ensure that the WBL percentage was between 60 and 70%, the accuracy window required for the Miniaci angle was 2.35 ± 0.13 degrees (range, 2.10-2.65°). This study suggests that to correct the HKA angle and the WBL percentage within the target range on two-dimensional WLRs, the Miniaci angle must be controlled to an accuracy of ± 1.63 and ± 1.18 degrees, respectively. Theoretically, the HKA angle is highly suitable as a preoperative planning parameter for HTO with a large permissible error and a small variability in the degree of change in the Miniaci angle (ΔMiniaci).

Feasibility and 3D Planning of a Novel Patient-Specific Instrumentation Technique in Medial Opening-Wedge High Tibial Osteotomy

A novel approach for opening-wedge high tibial osteotomy (OWHTO) with patient-specific instrumentation (PSI) was evaluated for its safety, feasibility, and accuracy. Next, the mechanical medial proximal tibial angle (mMPTA) was assessed as a potential planning angle by investigating the relation with the mechanical femorotibial angle (mFTA). Ten OWHTO cases were 3D planned using the mMPTA and operated with a customized 3D-printed wedge and cast which resembled the intended osteotomy opening. Patients were closely monitored for intraoperative and postoperative complications up to 1 year after surgery. Radiological assessment was conducted on full leg standing radiographs and supine lower limb computed tomography-scans preoperatively and 3 months after surgery. No intraoperative complications or logistical issues during PSI processing were observed. Absolute accuracy outcomes showed a correction error of 1.3° ± 1.1 mMPTA and 0.9° ± 0.6 mFTA with all osteotomies falling in (-2°; + 2°) mFTA around the target. The mMPTA and mFTA were found to have a strong correlation in both 3D (r = 0.842, p = 0.002) and 2D (r = 0.766, p = 0.01) imaging for effective correction. The study confirmed the development of a safe and feasible PSI technique in OWHTO with excellent accuracy outcomes. The strong correlation between the mMPTA and mFTA indicated that soft tissue changes after OWHTO are of minor significance to the final alignment in ligament-stable patients. Finally, the mMPTA was found to be a reliable planning angle in 3D software for obtaining the intended lower limb realignment and its use can therefore be recommended in modern OWHTO planning.

Focal proximal fibular angle: A potential indicator of the tibial mechanical axis in opening-wedge high tibial osteotomy

BACKGROUND

For opening-wedge high tibial osteotomy, correct alignment is essential for a better prognosis. It is difficult to evaluate the mechanical axis of the lower extremity or tibia using a single fluoroscopic image. This study aimed to discuss the use of focal proximal fibular angle (FPFA), which can be assessed by a single fluoroscopic image, as an intraoperative indicator.

METHODS

Eligible for analyses were 111 consecutively treated patients; for the final analyses 96 patients were included. The preoperative and postoperative medial proximal tibial angle (MPTA) and FPFA were measured. The relationship between these two angles, correction amount, weight-bearing line ratio and patient characteristics were analyzed.

RESULTS

The preoperative FPFA and MPTA were 96.5 ± 3.8° (mean ± standard deviation, SD) and 84.8 ± 3.0°, while the postoperative FPFA and MPTA were 87.6 ± 4.1° and 94.0 ± 3.5°, respectively. The preoperative and postoperative sums of the MPTA and FPFA were constant. The discrepancy was less than 3° in all knees, less than 2° in 92.7% knees and less than 1° in 68.8% knees. It was not correlated with age, sex, weight-bearing line ratio, or correction amount.

CONCLUSION

The study findings confirmed the constancy of the sum of the MPTA and FPFA. The FPFA can be easily evaluated on a single fluoroscopic image of the knee. Use of the FPFA as guidance may simplify the procedure of opening-wedge high tibial osteotomy and approximately predict the tibial mechanical axis.

Lateral tibial intercondylar eminence is a reliable reference for alignment correction in high tibial osteotomy

PURPOSE

The purpose of the study is to determine whether the lateral tibial intercondylar eminence (LTIE) is a reliable reference for alignment correction in high tibial osteotomy (HTO).

METHODS

A total of 1954 consecutive standing whole-leg radiography (WLR) examinations of 1373 adult patients with knee osteoarthritis between 2012 and 2019 were reviewed retrospectively; 145 patients were included, 53 males and 92 females, with a mean age of 63.3 years. Virtual simulation of HTO was performed to measure weight-bearing line (WBL) percentages and hip-knee-ankle (HKA) angles when the WBL passed through the Fujisawa, top, bottom, upper 1/3, and middle points of the lateral slope of the LTIE, and the positional relationship between the Fujisawa point and the lateral slope of the LTIE was determined.

RESULTS

When the WBL passed through the top, bottom, upper 1/3, and middle points of the lateral slope of the LTIE, the mean WBL percentages were 57.7% ± 2.1%, 74.6% ± 3.3%, 63.4% ± 2.1%, and 66.2% ± 2.3%, respectively, and the mean HKA angles were 182.1° ± 0.5°, 185.9° ± 0.8°, 183.3° ± 0.5°, and 184.0° ± 0.5°, respectively. When the WBL passed through the Fujisawa point, it was passing through 28.6% ± 12.7% of the width of the lateral slope (the top and bottom points were defined as 0% and 100%, respectively). When the WBL passed through the middle and upper 1/3 points of the lateral slope of the LTIE, the majority of cases (96.1%-100%) were within the limits of acceptability, as defined by the widely accepted standard of a postoperative HKA angle ranging from 183° to 186°.

CONCLUSION

The upper 1/3 and middle points of the lateral slope of the LTIE are reliable references for guiding the alignment correction in HTO. In clinical application, if 62%-66% of the postoperative WBL percentage is the acceptable target range, the upper 1/3 point of the lateral slope of the LTIE may be a better alternative than the midpoint. If the postoperative HKA angle between 183° and 186° is acceptable, the midpoint of the lateral slope of the LTIE may be better than the upper 1/3 point. These findings are crucial for the accuracy of the traditional intraoperative alignment assessment techniques.

LEVEL OF EVIDENCE

IV.

Open-wedge high tibial osteotomy using intraoperative control of joint line convergence angle with reference to preoperative supine radiograph

INTRODUCTION

Preoperative supine joint line convergence angle (JLCA) correlates with postoperative standing JLCA. Here, we compared the radiographic and clinical outcomes of knees with preoperative JLCAs of ≥ 4° and < 4° in open-wedge high tibial osteotomy (OWHTO). We hypothesized that the postoperative coronal alignment in both groups would not be affected by a change in JLCA if this change could predict before surgery.

MATERIALS AND METHODS

Eighty-four patients with medial knee osteoarthritis who underwent OWHTO were enrolled retrospectively. A weight-bearing line (WBL) ratio of 62% and a JCLA equivalent to the preoperative supine JLCA were anticipated in preoperative planning. These were intraoperatively set using an alignment rod and a radiolucent protractor under fluoroscopy. Soft tissue correction was defined as correction angle minus bone correction. The participants with preoperative JLCAs of < 4° (low-JLCA group) and ≥ 4° (high-JLCA group) were compared.

RESULTS

No significant difference in the coronal alignment was found between the groups after OWHTO. No significant differences in correction angle or bone correction were found between the groups, but the soft tissue correction in the high-JLCA group was higher than that in the low-JLCA group after OWHTO (p = 0.013).

CONCLUSIONS

When we controlled intraoperative JLCA, the postoperative coronal alignment was not affected by the change in JLCA and the differences in soft tissue correction between the low-JLCA and high-JLCA groups. However, overcorrection compared with the target coronal alignment remained in both groups.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Medial joint space width and convergence angle change with time after medial opening-wedge high tibial osteotomy

BACKGROUND

Although the medial joint space width (MJSW) is commonly used for radiographic evaluation of knee osteoarthritis, the changes in knee joint space width (JSW) during weight bearing after medial opening-wedge high tibial osteotomy (MOWHTO) remain unclear. This study aimed to depict how medial and lateral JSWs and convergence angles change gradually after MOWHTO.

METHODS

We retrospectively followed up 81 MOWHTO cases for over 45 months on average. Pre- and postoperative mechanical axes were recorded. The JSWs and convergence angles were measured preoperatively, immediately postoperatively, and 3-6, 9-12, and 21-24 months postoperatively. Patient-reported outcomes were measured using a visual analogue scale (VAS).

RESULTS

The mean mechanical femoral-tibial angle improved from 8.1° varus to 2.4° valgus. At the aforementioned times, the respective mean values of MJSW were 2.6, 3.5, 3.8, 4.0, and 4.2 mm; mean convergence angles were 4.8°, 2.9°, 2.2°, 2.1°, and 1.9°; and the mean VAS scores were 7.2, 7.8, 4.8, 1.4, and 1.3. The MJSW continued to increase significantly in the first year postoperatively and then plateaued for a minimum of 2 years follow up after MOWHTO. The convergence angle decreased significantly in the first 6 months postoperatively and was then maintained.

CONCLUSIONS

The MJSW, convergence angle, and VAS scores continued to improve through weight bearing during the first year after MOWHTO and were maintained for at least 2 years. Thus, JSW measurement may be an easy and representative way of radiographically monitoring the effect of MOWHTO.

3D-Printed Patient-Specific Instrumentation Technique Vs. Conventional Technique in Medial Open Wedge High Tibial Osteotomy: A Prospective Comparative Study

Purpose

The purpose of this study was to compare the accuracy and clinical outcomes of the medial open wedge high tibial osteotomy (MOWHTO) using a three-dimensional (3D-) printed patient-specific instrumentation (PSI) with that of conventional surgical techniques.

Methods

A prospective comparative study which included 18 patients who underwent MOWHTO using 3D-printed PSI technique (3D-printed group) and 19 patients with conventional technique was conducted from Jan 2019 to Dec 2019. After the preoperative planning, 3D-printed PSI (cutting guide model) was used in MOWHTO for 3D-printed group, while freehand osteotomies were adopted in the conventional group. The accuracy of MOWHTO for each method was compared using the radiological index obtained preoperatively and postoperatively, including mechanical femorotibial angle (mFTA) and medial mechanical proximal tibial angle (mMPTA), and correction error. Regular clinical outcomes were also compared between the 2 groups.

Results

The correction errors in the 3D-printed group were significantly lower than the conventional group (mFTA, 0.2° ± 0.6° vs. 1.2° ± 1.4°, P = 0.004) (mMPTA, 0.1° ± 0.4° vs. 2.2° ± 1.8°, P < 0.00001). There was a significantly shorter duration (P < 0.00001) and lower radiation exposures (P < 0.00001) for the osteotomy procedure in the 3D-printed group than in the conventional group. There were significantly higher subjective IKDC scores (P = 0.009) and Lysholm scores (P = 0.03) in the 3D-printed group at the 3-month follow-up, but not significantly different at other time points. Fewer complications occurred in the 3D-printed group.

Conclusions

With the assistance of the 3D-printed patient-specific cutting guide model, a safe and feasible MOWHTO can be conducted with superior accuracy than the conventional technique.

Rotation or flexion alters mechanical leg axis measurements comparably in patients with different coronal alignment

PURPOSE

Flexion and rotation of the knee joint are supposed to alter the measurement of the mechanical leg axis on long leg radiographs. However, in patients with varus or valgus alignment it has not been systematically analyzed so far. The hypothesis is that measurement of the mechanical leg axis is more influenced by flexion and rotation in presence of varus or valgus alignment compared to patients with a straight coronal alignment.

METHODS

3D surface models of the lower extremities of seven individuals with varying degrees of coronal alignment were created based on CT data. The coronal alignment of the seven individuals captured the range between 9° varus and 9° valgus with equal steps of 3°. Combinations of internal and external rotations of 10°, 20°, and 30° with flexion of 5°, 10°, 15°, 20°, and 30° were simulated. The mechanical leg axis was measured for each combination as the antero-posterior (ap)-projected hip-knee-ankle (HKA-) angle.

RESULTS

294 simulations with all combinations of rotation and flexion were performed. Ranges of deviation of HKA never showed a critical deviation of more than 3° from median values. Deviations from baseline appeared normally distributed for all flexion and rotation combinations (p < 0.05) and the probability for a deviation from the mean mechanical leg axis of more than 3° was less than 0.03 for all combinations. Comparability of the models, therefore, could be assumed.

CONCLUSION

Deviations in HKA-angle measurements, caused by rotation or flexion, does not vary relevantly through the range of coronal alignment of 9° varus to 9° valgus. As a clinical relevance, deviations in HKA-angle measurements can be considered as comparable in patients with different coronal alignment.

LEVEL OF EVIDENCE

III.

Large deformity correction in medial open-wedge high tibial osteotomy may cause degeneration of patellofemoral cartilage: A retrospective study

To evaluate retrospectively any association between the degree of deformity correction by medial open-wedge high tibial osteotomy (HTO) and patellofemoral joint degeneration. We hypothesized that development of patellofemoral joint degeneration depended on the degree of intraoperative deformity correction.Fifty-seven patients who underwent medial open-wedge HTO for treatment of osteoarthritis in one knee were included in this study. Knees were classified into degeneration (D) and non-degeneration (ND) groups according to worsening of the patellar and/or femoral trochlear cartilage at the time of hardware removal (D group, 27 knees) and no degeneration or improvement (ND group, 30 knees). We compared pre- to post-surgery change in hip-knee-ankle angle (HKA) and medial-proximal-tibial angle (MPTA), open-wedge HTO correction angle, and arthroscopic findings between groups.Mean age, height, weight, and body mass index were 54.1 ± 9.9 years, 160.4 ± 8.7 cm, 66.4 ± 12.1 kg, and 25.7 ± 3.3 kg/m, respectively. Change in both HKA and MPTA differed significantly between groups. The MPTA cut-off values to predict patellofemoral degeneration were determined to be 10°, associated with an AUC of 0.75 (95% confidence interval [CI] 0.62-0.87).This study evaluated retrospectively the effect of the correction angle during medial open-wedge HTO on patellofemoral joint degeneration. If deformity correction exceeds an MPTA of 10° during open-wedge HTO, degeneration of patellofemoral joint needs to be considered.Level of evidence: Level IV.

Intraoperative Fluoroscopic Assessment of Limb Alignment is a Reliable Predictor for Postoperative Limb Alignment in Biplanar Medial Opening-Wedge High Tibial Osteotomy

BACKGROUND

The purpose of this study was to assess the reliability of pre-, intra operative, and postoperative limb alignment measurements and investigate the correlation between the measurements in biplanar medial opening-wedge high tibial osteotomy.

METHODS

This study enrolled 59 knees undergoing biplanar opening-wedge high tibial osteotomy for primary medial osteoarthritis with varus deformity. Preoperative and postoperative standing lower leg radiographs and intraoperative fluoroscopic images were taken. Two independent examiners analyzed the radiologic data to assess lower limb alignment and mechanical axis (MA) deviation (percentage of MA position on tibial plateau). The effect of preoperative hip-knee-ankle angle and MA deviation, age, sex, body mass index (BMI), and joint line convergence angle on the discrepancy between intraoperative and postoperative MA deviation was analyzed.

RESULTS

The mean preoperative hip-knee-ankle angle and MA deviation were varus 7.7 ± 3.3° and 14.1 ± 15.1%, respectively. After osteotomy, the mean intraoperative postosteotomy MA deviation was 57.9 ± 2.1% in supine position, and the mean post-operative MA deviation increased to 63.9 ± 2.9% on standing radiographs. The mean difference between intraoperative postosteotomy MA deviation and postoperative MA deviation was 6.1 ± 2.2%. Linear regression analysis between intraoperative postosteotomy MA deviation and postoperative MA deviation showed a statistically significant linear relationship (R² = 0.449; P < .001). Multivariate regression analysis revealed that preoperative joint line convergence angle (β = 0.856; P < .001) and BMI (β = 0.349; P < .001) were significant positive predictors for the difference in MA deviation.

CONCLUSION

There was a significant linear relationship between intraoperative postosteotomy MA deviation and postoperative MA deviation following biplanar medial opening-wedge high tibial osteotomy. A greater discrepancy between MA deviations was significantly associated with higher BMI and joint line convergence angle.

Applicability of a modified angular correction measurement method for open-wedge high tibial osteotomy

PURPOSE

The purpose of this study was to evaluate the clinical potential of a new measurement technique for open-wedge high tibial osteotomy (HTO) based on the medial cortex opening (MCO) associated with the Miniaci preoperative planning technique.

METHODS

A retrospective review of 97 cases of valgus-producing HTO that were performed between 2008 and 2013, using the intra-operative fluoroscopic mechanical axis technique, was carried out. The Miniaci-based measurement technique was then used as a theoretical point of comparison with the intent to compare the disparity between postoperative and ideal lower extremity (LE) mechanical axis with the measured disparity between postoperative and Miniaci-based planned MCO.

RESULTS

A significant correlation was observed for the comparison of the disparity between postoperative and Miniaci-based planned MCO and the disparity between postoperative and ideal LE mechanical axis (0.53, P = 0.001). This would suggest that the MCO associated with the Miniaci preoperative planning technique would have resulted in a better alignment had it been the chosen method to guide the amount of osteotomy opening. No significant correlation was observed between perioperative and postoperative LE mechanical axis (n.s.), the variable on which the current technique is based, confirming the poor reliability of the fluoroscopic mechanical axis technique.

CONCLUSIONS

This study suggests a more accurate and precise technique of realizing the appropriate angular correction when performing a HTO, which could lead to better clinical outcomes.

LEVEL OF EVIDENCE

III.

Intra-articular corrective osteotomies combined with the Ilizarov technique for the treatment of deformities of the knee

Aims

To present our experience of using a combination of intra-articular osteotomy and external fixation to treat different deformities of the knee.

Patients and Methods

A total of six patients with a mean age of 26.5 years (15 to 50) with an abnormal hemi-joint line convergence angle (HJLCA) and mechanical axis deviation (MAD) were included. Elevation of a tibial hemiplateau or femoral condylar advancement was performed and limb lengthening with correction of residual deformity using a circular or monolateral Ilizarov frame.

Results

At a mean follow-up of 2.8 years (1.5 to 4.1), the mean HJLCA improved from 15.6° (10° to 23°) pre-operatively to 0.4° (0° to 2°). The mean MAD improved from 70.0 mm (20.1 to 118.5) pre-operatively to 9.1 mm (3 to 15). The mean tibiofemoral angle improved from 31.0° (8° to 54°) pre-operatively to 4.9° (2° to 8°). The mean limb-length discrepancy decreased from 6.3 cm (2.9 to 13.6) pre-operatively to 1.1 cm (0 to 5). All osteotomies and distraction zones healed without complications.

Conclusion

The use of intra-articular corrective osteotomies combined with the Ilizarov technique allowed correction of deformities of the knee joint with satisfactory HJLCA and overall mechanical axis in six patients with a good functional and cosmetic outcome in the short term. Cite this article: Bone Joint J 2017;99-B:204–10.

An Innovative Method of Assessing the Mechanical Axis Deviation in the Lower Limb in Standing Position

INTRODUCTION

Various methods of measuring mechanical axis deviation of lower limb have been described including radiographic and CT scanogram, intraoperative fluoroscopy with the use of an electrocautery cord. These methods determine the mechanical axis in a supine, non-weight bearing position. Although long cassette standing radiographic view is used for the purpose but is not available at most centres. A dynamic method of determining the mechanical axis in a weight bearing position was devised in this study.

AIM

The aim of the study was to describe a simpler and newer method in quantifying the mechanical axis deviation in places where full length cassettes for standing X rays are not available.

MATERIALS AND METHODS

A pilot study was conducted on 15 patients. The deviation from the mechanical axis was measured using a manually operated, hydraulic mechanism based, elevating scissor lift table. Patient was asked to stand erect over the elevating lift table with both patellae facing forward and C-arm image intensifier was positioned horizontally. Radiological markers were tied to a radio-opaque thread and placed at the centre of head of the femur and another at the centre of the tibio-talar joint. C-arm views of the hip, ankle and knee joint were taken to confirm the correct position of the marker by varying the height of the lift table.

RESULTS

The mechanical axis deviation values were recorded by measuring distance between the centre of the knee and radio-opaque thread in cm. This was measured in each case both clinically and from the image on the monitor. The two values were found to be statistically same. Pain was measured on VAS. Mechanical axis deviation values and VAS score were found to be positively significantly correlated.

CONCLUSION

This technique is dynamic, unique and accurate as compared to other methods for assessing mechanical axis deviation in a weight bearing position.

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.

Inter-observer and intra-observer reliability of mechanical axis alignment before and after total knee arthroplasty using long leg radiographs

BACKGROUND

Long leg radiographs (LLRs) are commonly performed for assessment of mechanical alignment and operative planning in patients undergoing total knee arthroplasty (TKA). The aim of this study was to determine the inter- and intra-observer reliability of alignment measured by observers of different levels of experience.

METHODS

Forty patients on the waiting list for a TKA had pre- and post-operative standardised LLRs. We analysed the measurements of mechanical axis alignment between an orthopaedic surgeon, a senior orthopaedic registrar, a junior orthopaedic registrar, and a medical student. Reviewers performed blinded measurements on the same computer screen. These measurements were repeated three months later to assess intra-observer reliability. Furthermore high-resolution screens were compared with standard hospital computer screens to investigate whether monitoring quality influenced the accuracy of measurements of alignment.

RESULTS

Inter-observer reliability was high for pre-operative LLRs with an intra-class correlation (ICC) of >0.9 at all experience levels. Post-operative ICC was lowest between the surgeon and the medical student at 0.7. Intra-observer reliability was high at all experience levels. Larger deformities appeared to have exaggerated measurements for both pre- and post-operative images. There appeared to be no effect of the monitor size and quality on the accuracy of measurement.

CONCLUSIONS

Long leg radiographs can be used to measure mechanical axis alignment with strong reliability across different levels of experience. This information is important for the evaluation of knee alignment measurements in current clinical practice, to assess severity of deformity and to accompany pre-operative planning and post-operative evaluation.

LEVEL OF EVIDENCE

III.