Is patient-specific instrumentation more precise than conventional techniques and navigation in achieving planned correction in high tibial osteotomy?

Patient-specific cutting guides increase accuracy of medial opening wedge high tibial osteotomy procedure: A retrospective case-control study

Purpose

To compare the accuracy of patient-specific guides (PSCG) to the standard technique in medial open-wedge high tibial osteotomy (OWHTO). Secondary objectives were to evaluate factors that could influence accuracy and to compare the complication rate and operating time for both procedures.

Methods

A retrospective analysis of prospective collected data was performed. Between March 2011 and May 2018, 49 patients with isolated medial knee osteoarthritis who were operated for OWHTO using PSCG and 38 patients using the standard technique were included. Preoperative and postoperative deformities were evaluated on long leg radiographs by measuring the mechanical medial proximal tibial angle, mechanical lateral distal femoral angle, hip knee ankle angle (HKA), and joint line convergence angle. Pre- and postoperative posterior tibial slope was also evaluated. Accuracy was evaluated by analysing the difference between the preoperative planned and the actual postoperative HKA. Operating time and complication rate were also recorded in both groups.

Results

The mean preoperative HKA was 173.4° (±3.1°) in the PSCG group and 173.3° (±2.4°) in the standard group (p = 0.8416). Mean planned HKA were 182.8° (±1.1°) and 184.0° (±0°) respectively for the PSCG and the standard group. Mean postoperative HKA were 181.9° (±1.9°) and 182.6° (±3.1°) respectively for the PSCG and the standard group. An accuracy of ±2° in the HKA was achieved in 44 (90%) in the PSCG group and 24 (65%) in the standard group (p = 0.006). The probability of achieving a HKA accuracy was four times higher for patients in the PSCG group (odds ratio [OR] = 4.06, [1.1; 15.3], p = 0.038). Also, higher preoperative Ahlback grade was associated with precision, all other parameters being equal (OR = 4.2, [0.13; 0.97], p = 0.04).

Conclusion

In this study, the PSCG technique was significantly more accurate for achieving the planned HKA in OWHTO. Complication rates and operating times were comparable between groups.

Level of Evidence

Level IV, case-control study.

Computer aided multiplanar osteotomy using patient specific instrumentation to treat cubitus varus in children

Cubitus varus deformity is a common complication of supracondylar fractures in children. Anatomic correction is the key to obtaining good functional results and avoiding later symptomatic degradation. Different techniques have been described, mainly lateral closing wedge osteotomy. A medial opening wedge osteotomy seems more intuitive, allowing an anatomic reduction, but it is technically challenging. Two-plane radiographs are too simplistic to appreciate the 3D deformity. With medical imaging and image processing advances, three-dimensional (3D) virtual models of a patient's anatomy can be generated. Rapid 3D printing has allowed virtual simulations of surgical corrections to be transferred to real-world applications in the operating room, allowing more precise and accurate surgery with better 3D corrections. 3D computer modeling with the development of customized drilling and cutting guides allows complex medial opening wedge osteotomy for correction of cubitus varus deformity in immature children with best-fit plate synthesis. LEVEL OF EVIDENCE: IV.

Better clinical outcomes and faster weight bearing after medial opening-wedge high tibial osteotomy using allogeneic than synthetic graft: A secondary analysis of a Francophone Arthroscopy Society Symposium

INTRODUCTION

Although an autogenous graft has the highest rate of bone union to fill the void created in medial opening wedge high tibial osteotomy (MOWHTO), it also has some disadvantages, such as prolonged surgical time, donor site pain and morbidity. Two possible candidates for ideal grafts to replace autogenous grafts are allogeneic and synthetic graft, which are free from donor site pain and morbidity. However, previous reports comparing the clinical results of allogeneic to synthetic graft have been limited and controversial. The purpose of this study is to compare radiological findings and clinical outcomes of using synthetic versus allogenic graft to fill the void created in MOWHTO.

HYPOTHESIS

The present clinical study hypothesized that allogenic graft to fill the void would allow the higher rate of bone union and better clinical outcomes.

MATERIAL AND METHODS

This study compared the clinical and radiological outcomes of 95 patients who received MOWHTO to fill the void with either synthetic or allogenic graft (44 in Syn group, 51 in Allo group). Preoperatively and postoperatively, all patients were clinically evaluated; Return to work, Tegner activity score, and the Western Ontario and Macmaster University scores were reported. Radiographically, osteoarthritis grade and pre- and postoperative parameters were reported, including Hip-knee-ankle angle, mechanical lateral distal femoral angle, medial proximal tibial angle, joint line convergence angle, proximal posterior tibial angle, and limb length discrepancy. Perioperative details and complications were also reported.

RESULTS

Mean follow-up (months) were 24.0±1.3 in Syn group and 26.8±1.2 in Allo group (p=0.13). The postoperative improvement of pain and global WOMAC scores in Allo group were significantly better than in Syn group (ΔPain of WOMAC: Syn group 27.8±4.4, Allo group 49.3±3.8, p value <0.001*) (ΔGlobal score of WOMAC: Syn group 16.7±3.2, Allo group 37.4±4.9, p value=0.002*). The risk of hinge fracture in Syn group was significantly higher than in Allo group (Hinge fracture by Takeuchi grade (0/1/2/3): Syn group 37/3/3/1, Allo group 43/8/0/0, p value=0.04*). The timing of full weight bearing in Allo group was significantly earlier than in Syn group (Weight Bearing (1=FWB, 2=PWB 3wk, 3=PWB 6wk): Syn group 2.7±0.1, Allo group 2.3±0.1, p value=0.01*).

DISCUSSION

The use of allogenic graft to fill the void in MOWHTO does not show superiority in bone union compared to synthetic graft, however it improves pain, function, decreases the risk of hinge fracture and allows faster weight bearing than synthetic graft.

LEVEL OF PROOF

III; Case-control study.

Personalised opening wedge high tibial osteotomy with patient-specific plates and instrumentation accurately controls coronal correction and posterior slope: Results from a prospective first case series

BACKGROUND

Patient specific devices represent a promising tool to improve accuracy and simplify high tibial osteotomy (HTO) procedures. The current study aims to assess accuracy of the correction of alignment and posterior tibial slope (PTS), and provide patient reported outcomes (PROMs) of a new personalised cutting guide and fixation plate (TOKA) system for HTO in patients with medial osteoarthritis (OA) and varus knee.

METHODS

25 patients (mean age 54.4 years) with medial OA and varus knee malalignment who underwent HTO with the TOKA system were prospectively evaluated pre-operatively, 1, 3, 6 and 12-months follow-up. Standing long-leg and lateral radiographs of the knee were used to assess the hip-knee-ankle (HKA) angle and the PTS, respectively. Accuracy was defined as the difference in planned minus achieved correction. The patient reported outcomes collected were the KOOS score, EQ5D, KSS score, and VAS pain scores. All statistical analyses were performed using IBM SPSS Statistics for Windows.

RESULTS

The mean preoperative HKA was 170.7° (SD ± 3.2°); the mean postoperative HKA was 177.4° (SD ± 2.9°). The overall mean difference between planned and achieved correction in terms of HKA was 2.1° (SD ± 2.0°). The mean difference between planned and achieved PTS was 0.2° (SD ± 0.4°). All the assessed PROMs had a significant (p < 0.001) increase from the pre-operative value to postoperative evaluation and showed a significant (p < 0.001) improvement with follow-up time.

CONCLUSIONS

TOKA personalised HTO system showed accurate correction in terms of both coronal and sagittal alignment, and excellent patient reported outcomes.

LEVEL OF EVIDENCE

4, prospective case series. Registration in public trial registry: registered at ClinicalTrial.gov [NCT04574570].

Patellar medial-lateral position can be used to correct the effect of leg rotation on preoperative planning in total knee arthroplasty for varus knees

BACKGROUND

Lower limb malrotations can be observed in long leg radiographs, affecting the measurement of the angle between the mechanical and anatomical axes. The purposes were to analyze the effect of limb rotation and to evaluate the accuracy of the corrected angle between the mechanical and anatomical axes based on the patellar ML position.

HYPOTHESIS

The hypothesis was that the correction of the angle between the mechanical and anatomical axes according to the patellar ML position can reduce the error from the angle in the true AP view in most of the knees.

PATIENTS AND METHODS

A total of 100 consecutive knees with varus deformity undergoing primary total knee arthroplasty were included. Computed tomography images were digitally reconstructed in the neutral position, and internally and externally rotated at 10° and 20°, respectively. The patellar ML position relative to the medial (0%) and lateral (100%) epicondyles and the angle between the mechanical and anatomical axes of the femur were measured. The corrected angle between the mechanical and anatomical axes was calculated using the averaged translational ratio.

RESULTS

In the neutral position, the patellar center position was 56.1% (standard deviation [SD]=4.7%), which was 31.4% (SD=7.2%) and 80.2% (SD=5.4%) in the 20° internal and external rotation, respectively. The angle between the mechanical and anatomical axes was 2.6° (SD=2.0°) and 8.1° (SD=2.1°) in the 20° internal and external rotation, respectively. On average, if the patellar center shifted 10%, the change of the angle between the mechanical and anatomical axes of the femur was 1.13°. Applying the corrected angle, a discrepancy from the neutral position decreased.

CONCLUSION

The method to correct the angle between the mechanical and anatomical axes according to the patellar ML position can be used to reduce the measurement error for preoperative planning using a long leg radiograph.

LEVEL OF EVIDENCE

III.

An artificial intelligence based on a convolutional neural network allows a precise analysis of the alignment of the lower limb

PURPOSE

The objective of this study was to develop a numeric tool to automate the analysis of deformity from lower limb telemetry and assess its accuracy. Our hypothesis was that artificial intelligence (AI) algorithm would be able to determine mechanical and anatomical angles to within 1°.

METHODS

After institutional review board approval, 1175 anonymized patient telemetries were extracted from a database of more than ten thousand telemetries. From this selection, 31 packs of telemetries were composed and sent to 11 orthopaedic surgeons for analysis. Each surgeon had to identify on the telemetries fourteen landmarks allowing determination of the following four angles: hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), and joint line convergence angle (JLCA). An algorithm based on a machine learning process was trained on our database to automatically determine angles. The reliability of the algorithm was evaluated by calculating the difference of determination precision between the surgeons and the algorithm.

RESULTS

The analysis time for obtaining 28 points and 8 angles per image was 48 ± 12 s for the algorithm. The average difference between the angles measured by the surgeons and the algorithm was around 1.9° for all the angles of interest: 1.3° for HKA, 1.6° for MPTA, 2.1° for LDFA, and 2.4° for JLCA. Intraclass correlation was greater than 95% for all angles.

CONCLUSION

The algorithm showed high accuracy for automated angle measurement, allowing the estimation of limb frontal alignment to the nearest degree.

Application of SolidWorks software in preoperative planning of high tibial osteotomy

Purpose

Open-wedge high tibial osteotomy (HTO) is a common surgical treatment for medial osteoarthritis in young and active patients. The accuracy of osteotomy is closely associated with postoperative efficacy. The accuracy of digital preoperative planning is higher than that of the preoperative manual measurement and several computer software with varying accuracy and convenience are used for digital preoperative planning. This study aimed to use the SolidWorks software for HTO preoperative planning and to determine its accuracy and reliability in HTO preoperative planning.

Methods

We reviewed the data of 28 patients with 54 with medial compartment knee arthritis who underwent open-wedge HTO preoperative planning using SolidWorks between June 2019 and March 2021. The standard anteroposterior standing whole-leg radiographs were assessed before and 6 weeks after the surgery. The correction angle, weight-bearing line (WBL) ratio, mechanical femorotibial angle (mFTA), and medial proximal tibial angle (MPTA) before and after the surgery were compared. The clinical results were evaluated using the Knee Society score.

Results

At 6 weeks after the surgery, the WBL ratio was corrected from 16.8% to 50.5%, mFTA was corrected from 6.4° varus to 1.2° valgus, and MPTA was corrected from 83.4° to 89.3°. No significant difference was observed between the predicted correction angle before the surgery and the correction angle measured 6 weeks after the surgery (t = -1.745, p = 0.087). The knee score and function score of Knee Society increased from 76.4 and 80.7 before surgery to 95.0 and 95.7, respectively.

Conclusions

The SolidWorks software showed high accuracy and reliability in preoperative planning of open-wedge HTO in patients with medial compartment knee arthritis.

Is Patient-Specific Instrumentation Accurate and Necessary for Open-Wedge High Tibial Osteotomy? A Meta-Analysis

The purpose of this meta-analysis was to identify if patient-specific instrumentation (PSI) could increase the accuracy of the correction in high tibial osteotomy (HTO) and to explore the assessment indices and the necessity of using a PSI in HTO. A systematic search was carried out using online databases. A total of 466 patients were included in 11 papers that matched the inclusion criteria. To evaluate the accuracy of PSI-assisted HTO, the weight bearing line ratio (WBL%), hip-knee-ankle angle (HKA), mechanical medial proximal tibial angle (mMPTA), and posterior tibial slope angle (PTSA) were measured preoperatively and postoperatively and compared to the designed target values. Statistical analysis was performed after strict data extraction with Review Manager (version 5.4). Significant differences were detected in WBL% (MD = -36.41; 95% CI: -42.30 to -30.53; p < 0.00001), HKA (MD = -9.95; 95% CI: -11.65 to -8.25; p < 0.00001), and mMPTA (MD = -8.40; 95% CI:-10.27 to -6.53; p < 0.00001) but not in PTSA (MD = 0.34; 95% CI: -0.59 to 1.27; p = 0.47) between preoperative and postoperative measurements. There was no significant difference between the designed target values and the postoperative correction values of HKA (MD = 0.14; 95% CI: -0.19 to 0.47; p = 0.41) or mMPTA (MD = 0.11; 95% CI -0.34 to 0.55; p = 0.64). The data show that 3D-based planning of PSI for HTO is both accurate and safe. WBL%, HKA, and mMPTA were the optimal evaluation indicators of coronal plane correction. Sagittal correction is best evaluated by the PTSA. The present study reports that PSI is accurate but not necessary in typical HTO.

No benefits of knee osteotomy patient's specific instrumentation in experienced surgeon hands

PURPOSE

To compare the clinical and radiological outcomes of patient-specific instrumentation (PSI) with the conventional free hand (FH) technique in performing coronal plane corrective knee osteotomies in terms of limb alignment and functional scores. The hypothesis is that conventional FH technique in experienced hands with proper pre-operative planning is as precise as PSI.

METHODS

Patients who underwent coronal plane corrective knee osteotomies with either PSI or FH technique between 2017 and 2019 by the same senior surgeon and have a minimum of 2 years follow-up period were included in this study. A total of 91 knees (84 patients) with mean age of 42.9 ± 12.5 years who had a pre- and post-operative complete weight-bearing radiographic work-up (50 of them were performed with the FH technique and 41 by means of PSI) were included for comparison. The data were retrospectively reviewed both radiologically and clinically using the Knee Injury and Osteoarthritis Outcome Score (KOOS) sub-scores. All cases in both groups were evaluated for the following measurements: hip-knee-ankle (HKA), medial proximal tibial angle (MPTA), mechanical lateral distal femoral angle (mLDFA), and joint line convergence angle (JLCA) both preoperatively and postoperatively. In addition, FH and PSI osteotomy cases were also compared for their precision in achieving the target correction that was planned preoperatively. All cases were also evaluated clinically preoperatively and at 2-year follow-up using KOOS sub-scores and the two groups were compared.

RESULTS

The mean HKA precision was 1.5 ± 0.9 in FH group and 1.3 ± 0.7 in PSI (P value = n.s.), the mean MPTA precision was 1.6 ± 1.6 in FH group and 2.1 ± 1.2 in PSI (P value = n.s.), the mean m-LDFA precision was 1.9 ± 1.7 in FH group and 1.4 ± 1.3 in PSI (P value = n.s.), and the mean JLCA precision in the FH group was 1.5 ± 1.2 and 1.7 ± 1.2 in PSI (P value = n.s.). For all the radiographic parameters, there were no statistically significant differences between the target correction and the obtained correction in both groups. Moreover, PSI and FH techniques were comparable in terms of clinical outcomes and no significant difference was found between the two groups in any of the 2-year follow-up KOOS sub-scores.

CONCLUSION

Conventional FH method in the hands of experienced surgeons is as precise as PSI in reliably achieving the planned correction in different coronal plane knee corrective osteotomies. Moreover, there was also no difference between both methods in the 2-year clinical outcome scores.

Experimental investigation of the risk of lateral cortex fracture during valgus tibial osteotomy

BACKGROUND

Valgus-producing medial opening-wedge proximal tibial osteotomies (V-MOW-PTO) are used to treat isolated medial-compartment knee osteoarthritis in patients with varus malalignment. A fracture of the lateral cortical hinge is a risk factor for poor outcomes. Implantation of a protective K-wire has been suggested to prevent this complication. The primary objective of this bench study was to assess the ability of a protective K-wire to prevent lateral cortical fractures. The secondary objective was to evaluate the influence of the opening speed on fracture risk during the osteotomy.

HYPOTHESIS

The primary hypothesis was that a protective K-wire decreased the risk of hinge fracture. The secondary hypothesis was that this risk was greater when the opening speed was high.

MATERIALS AND METHODS

We performed an experimental study of 20 simulated thermoplastic-polymer (ABS) tibias obtained by 3D printing to assess the effects of wedge-opening speed (high vs. low) and presence of a protective K-wire (yes vs. no). The opening rates were determined in a preliminary study of Sawbone® specimens opened using a distractor. The opening rate was measured using an accelerometer via a motion-capture glove. After assessing several high and low opening speeds, we selected 38mm/min and 152mm/min for the study. We divided the 20 ABS specimens into four groups of five each: high speed and K-wire, low speed and K-wire, high speed and no K-wire, and low speed and no K-wire. The force was applied using an Instron™ testing machine until construct failure. The primary outcome measure was the load at failure (N) and the secondary outcome measures were the displacement (mm) and maximum time to failure (s).

RESULTS

At both speeds, values were significantly higher with vs. without a K-wire for load to failure (low: 253.3N vs. 175.5N, p<0.01; high: 262.2N vs. 154.1N, p<0.01), displacement (low: 11.1mm vs. 8.7mm, p<0.01; high: 11mm vs. 8.9mm; p=0.012), and maximal time to failure (low: 11.4 s vs. 8.9 s; p=0.012; high: 2.2 s vs. 1.8 s; p=0.011). Thus, the osteotomy opening speed seemed to have no influence on the risk of lateral cortex fracture.

DISCUSSION

Our main hypothesis was confirmed but our secondary hypothesis was refuted: a protective K-wire significantly decreased the risk of hinge fracture, whereas the osteotomy opening speed had no influence. To our knowledge, this is the first published study assessing the potential influence of opening speed on risk of lateral cortex fracture. Our findings were obtained in the laboratory and should be evaluated in clinical practice.

LEVEL OF EVIDENCE

IV, experimental study.

Comparative outcomes of patient-specific instrumentation, the conventional method and navigation assistance in open-wedge high tibial osteotomy: A prospective comparative study with a two-year follow up

BACKGROUND

To compare and analyze the correction precision, clinical outcomes and complications among the three methods of performing open-wedge high tibial osteotomy (HTO), including patient-specific instrumentation (PSI), conventional method and navigation assistance.

METHODS

In this prospective, single-center study, we randomly assigned patients with knee osteoarthritis in a 1:1:1 ratio to undergo Open-wedge high tibial osteotomy (OWHTO) with conventional method, navigation assistance or PSI. The primary outcome was the target/observed hip-knee-ankle (HKA) angle difference at 1 month postoperatively. Secondary outcomes were changes in the postoperative posterior tibial slope (PTS) at 1 month and clinical outcomes including knee pain on a visual analogue scale (ranging from 0 to 100, with higher scores indicating more severe pain), Lysholm and Western Ontario and McMaster Universities Osteoarthritis Index (ranging from 0 to 240) scores at 1 month, 6 months, 12 months, and 24 months.

RESULTS

From 2017 through 2019, a total of 608 patients were screened; of those patients, 144 were enrolled, with 48 in each group. The primary outcome of the HKA difference was 2.6 ± 2.0° in the conventional group, 2.3 ± 1.5° in the navigation group and 0.6 ± 1.0° in the PSI group (P < 0.001). Secondary outcomes including changes in the postoperative PTS and clinical outcomes at 1 month, 6 months, and 12 months were in the same direction as the primary outcome. There were no significant differences in the complications among the three groups.

CONCLUSIONS

In the present study, none of the three methods showed superiority in objective correction precision and clinical outcomes at 2 years.

3D planning and patient-specific surgical guides in forearm osteotomy in children: Radiographic accuracy and clinical morbidity

INTRODUCTION

Three-dimensional (3D) planning and patient-specific surgical guides are increasingly used in the treatment of skeletal deformities. The present study hypothesis was that they are reliable in forearm osteotomy in children, with low morbidity.

MATERIAL AND METHODS

Twenty-there children with one or several osteotomies to correct forearm deformities were retrospectively included: 9 (20 osteotomies) with surgical guide (G+), and 14 (28 osteotomies) without (G-). Etiologies comprised 8 cases of Madelung disease (3G+, 5G-) and 15 of post-traumatic malunion (6G+, 9G-). Mean age at surgery was 14.8±1.9 years. The patient-specific 3D-printed polyamide guides were produced from 3D virtual models based on 3D CT reconstruction. Mean follow-up was 22.1±13.6 months.

RESULTS

Mean correction error was 5.3°±4.1 and 4.2°±4.1 in the frontal and sagittal planes respectively in G+ (p=0.6). Surgery time was significantly shorter in G+, by a mean 42min (p=0.02). Mean total radiation dose (preoperative CT+intraoperative fluoroscopy) was significantly higher in G+ (p<0.0001). Complications rates were similar between groups. Improvement in PRWE score was significantly greater in G+.

CONCLUSION

The present preliminary results were encouraging. 3D planning and patient-specific surgical guides can be used in the treatment of forearm deformity in children.

LEVEL OF EVIDENCE

III; retrospective cohort study.

Custom-Made Devices Represent a Promising Tool to Increase Correction Accuracy of High Tibial Osteotomy: A Systematic Review of the Literature and Presentation of Pilot Cases with a New 3D-Printed System

Background: The accuracy of the coronal alignment corrections using conventional high tibial osteotomy (HTO) falls short, and multiplanar deformities of the tibia require consideration of both the coronal and sagittal planes. Patient-specific instrumentations have been introduced to improve the control of the correction. Clear evidence about customized devices for HTO and their correction accuracy lacks. Methods: The databases PUBMED and EMBASE were systematically screened for human and cadaveric studies about the use of customized devices for high tibial osteotomy and their outcomes concerning correction accuracy. Furthermore, a 3D-printed customized system for valgus HTO with three pilot cases at one-year follow-up was presented. Results: 28 studies were included. The most commonly used custom-made devices for HTO were found to be cutting guides. Reported differences between the achieved and targeted correction of hip-knee-ankle angle and the posterior tibial slope were 3° or under. The three pilot cases that underwent personalized HTO with a new 3D-printed device presented satisfactory alignment and clinical outcomes at one-year follow-up. Conclusion: The available patient-specific devices described in the literature, including the one used in the preliminary cases of the current study, showed promising results in increasing the accuracy of correction in HTO procedure.

Double level osteotomy for genu varum: Is a return to sport possible?

INTRODUCTION

A double level osteotomy (DLO) may be indicated in patients with genu varum when the deformity involves both the tibia and femur. These patients, who are often young and active, have a high functional demand and hope for a rapid return to sport. The purpose of our study was to assess return to sport and functional outcomes following DLO for symptomatic genu varum.

MATERIALS AND METHODS

A total of 40 patients (mean age 45.5±2 years) who underwent a DLO between 2018 and 2020, performed in 2 different hospitals, were reviewed after a minimum follow-up of 1-year. The mean initial varus was 11±2°. The type of sport and frequency of participation (UCLA activity score) as well as time to return to sport and level of activity recovered were defined as the primary endpoints. Functional scores were also assessed with the knee injury and osteoarthritis outcome score (KOOS).

RESULTS

At the last follow-up, 87.5% (n=35) of patients reported that they had returned to sport. The mean time to return to sport was 6±1 months with a significant difference (p<0.001) between the pre- and postoperative UCLA activity scores. There was a strong correlation between the presence of a joint line obliquity >3° and decreased functional outcomes (p<0.0001). The overall KOOS score improved (p<0.001) by a mean of 38.6 points after the correction. The 8 lateral cortical fractures (Takeuchi type I and II) and the 2 medial cortical fractures (Nakayama type 1) that were found had no impact on functional outcomes (p>0.05).

CONCLUSION

Our findings demonstrated that DLO provided rapid return to sport, thus making it possible to meet the functional demands and expectations of patients.

LEVEL OF EVIDENCE

IV; Retrospective study.

Improved Accuracy of Coronal Alignment Can Be Attained Using 3D-Printed Patient-Specific Instrumentation for Knee Osteotomies: A Systematic Review of Level III and IV Studies

PURPOSE

To evaluate the accuracy and precision of postoperative coronal plane alignment using 3D-printed patient-specific instrumentation (PSI) in the setting of proximal tibial or distal femoral osteotomies.

METHODS

A systematic review evaluating the accuracy of 3D-printed PSI for coronal plane alignment correcting knee osteotomies was performed. The primary outcomes were accuracy of coronal plane limb alignment correction and number of correction outliers. Secondary variables were duration of surgery, number of intraoperative fluoroscopic images, complications, cost, and clinical outcomes (as applicable).

RESULTS

Ninety-three studies were identified, and 14 were included in the final analysis. Overall, mean postoperative deviation from target correction ranged from 0.3° to 1° for all studies using hip-knee angle measurements and 2.3% to 4.9% for all studies using weight-bearing line measurements. The incidence of correction outliers was assessed in 8 total studies and ranged from 0 to 25% (total n = 10 knees) of patients corrected with 3D-printed PSI. Osteotomies performed with 3D-printed cutting guides or wedges demonstrated significantly shorter operative times (P < .05) and fewer intraoperative fluoroscopic images (P < .05) than control groups in four case control studies.

CONCLUSION

Patients undergoing distal femoral osteotomy or proximal tibial osteotomy procedures with 3D-printed patient-specific cutting guides and wedges had highly accurate coronal plane alignment with a low rate of outliers. Patients treated with 3D printed PSI also demonstrated significantly shorter operative times and decreased intraoperative fluoroscopy when compared to conventional techniques.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III-IV studies.

Biplanar high tibial osteotomy for the combined correction of varus and posterior tibial slope malalignment

Varus malalignment combined with an increased posterior tibial slope (PTS) in the ACL deficient knee is a frequent pathology; yet, treatment for this condition remains challenging. The presented biplanar osteotomy technique allows to simultaneously address both components of malalignment in a single step. A detailed preoperative planning is best achieved by means of a digital planning software and constant intraoperative imaging is performed to verify the correction angle. A bony wedge is resected along with the extension osteotomy according to the preoperative planning and the medial-opening tibial osteotomy site is filled with bone allograft. Two bicortical lag screws are placed in anterior-posterior direction to secure the extension osteotomy, whereas a plate fixation is used for the medial-open osteotomy.

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.

Accuracy of the correction achieved after a valgus high tibial osteotomy: Comparison of the Hernigou table and navigation

INTRODUCTION

The outcome of a medial opening wedge valgus high tibial osteotomy indicated for the treatment of isolated medial tibiofemoral osteoarthritis depends mainly on the accuracy of the correction of the hip-knee-ankle angle (HKAA) and the mechanical medial proximal tibial angle (mMPTA). Most authors aim for a desired correction target between 2° and 4° of valgus. Several planning and surgical techniques have been described to achieve this target value that is specific to each surgeon.

OBJECTIVE

The purpose of this study was to compare the accuracy of the correction achieved using either the Hernigou table (HT) planning method or a computer-assisted navigation system (CAS). It was hypothesized that no difference would be found between these 2 techniques.

MATERIALS AND METHODS

This retrospective single-center study involved 43 knees: 21 in the HT group and 22 in the CAS group. Two surgeons (ME, JYJ), who were experts in 1 of the 2 planning methods performed these procedures, with a single surgeon assigned to each group. The correction was noted in the operative report and was considered to be the desired correction target. The surgical correction was calculated by comparing preoperative and immediate postoperative mMPTA measurements. The surgical accuracy, where a value close to 0 represented optimal accuracy, was defined as the absolute value of the difference between the correction target set by the surgeon and the surgical correction achieved. The median accuracy between the 2 groups was compared by a Mann-Whitney U test (significance level at 5%). The number of patients deviating from the target by>3° was analyzed with a Fisher exact test (significance level at 5%). Pre- and postoperative comparisons of the HKAA measurements could not be used because the measurement was not performed postoperatively for the CAS group.

RESULTS

The median surgical accuracy on the mMPTA was 1.4° (0-4.1) for the HT group versus 1.9° (0.2-6.7) for the CAS group (p=0.85). Sixteen procedures (76%) were performed with an accuracy of<3° in the HT group versus 15 in the CAS group (68%) (p=0.73).

DISCUSSION-CONCLUSION

The working hypothesis was confirmed: no differences were found between the HT and CAS groups regarding the surgical accuracy in achieving the corrections set in this series. We therefore demonstrated that HT was a highly accessible, simple and reliable technique for achieving the planned target. It can be used widely.

LEVEL OF EVIDENCE

III; comparative retrospective series.

The range of the required anterolateral cortex osteotomy distance varied widely in biplanar open wedge high tibial osteotomy

Background

To evaluate the anterolateral cortex distance between the lateral edge of the flange and hinge point in surgical simulations of biplanar open wedge high tibial osteotomy (OWHTO) using computed tomography (CT) images.

Methods

A total of 110 knees treated with OWHTO for medial knee osteoarthritis with varus malalignment were enrolled. Surgical simulations of biplanar OWHTO, including the transverse and ascending cuts, were performed in the standard manner using preoperative CT images. The distance between the lateral edge of the flange and the hinge point was measured. In addition, another plane of the ascending cut was defined through the hinge point. The angle between these two planes of the ascending cut was measured in the axial plane.

Results

The mean anterolateral cortex distance was 9.4 ± 4.6 mm (range, − 1.5 mm – 20.3 mm). In 3 knees, osteotomy of the anterolateral cortex was not needed. The mean value of the angle between the two ascending cut planes was 8.4 ± 3.6° (range, − 2.1° – 14.8°), which meant that osteotomy of anterolateral cortex was not needed when the ascending cut was performed at this angle. Moreover, these two values increased when the flange thickness was changed from one-third to one-fourth of the anteroposterior tibial diameter or the angle between the transverse and ascending cuts was changed from 110° to 120°.

Conclusions

In biplanar OWHTO, anterolateral cortex osteotomy would be required. However, the range of the required anterolateral cortex osteotomy distance varied widely and the required anterolateral cortex osteotomy distance depended on the flange thickness and the angle between the transverse and ascending cuts. In addition, change of the ascending cut plane can change the necessity of anterolateral cortex osteotomy.

How to achieve an optimal alignment in medial opening wedge high tibial osteotomy?

Medial opening wedge high tibial osteotomy (MOWHTO) is a widely used surgical treatment option for medial compartmental osteoarthritis with varus deformity. It is important that proper lower limb alignment is achieved. However, there has been no consensus about an optimal alignment in MOWHTO. Most studies suggest that achieving valgus alignment is necessary, and recent studies support slight valgus mechanical alignment of less than 3° of mechanical femorotibial angle. Overcorrection and undercorrection is not recommended for achieving good surgical outcomes. To prevent undercorrection and overcorrection in MOWHTO, the method of placing the weight-bearing line in the target range must be precise. There are several ways to place a weight-bearing line within the target range. While the most important factor for a successful MOWHTO is achieving an ideal mechanical axis correction, there are a few other factors to consider, including joint line obliquity, posterior tibial slope, ligament balancing, and patellar height. Several factors exist that lead to undercorrection and overcorrection. Preoperative amount of varus deformity, lateral hinge fracture, and fixation failure can result in undercorrection, while medial soft tissue laxity and the amount of correction angle and target point beyond hypomochlion can result in overcorrection. This study aimed to review the literature on optimal alignment in MOWHTO and report on the factors to be considered to prevent correction errors and how to achieve an optimal alignment.

Dislocated hinge fractures are associated with malunion after lateral closing wedge distal femoral osteotomy

PURPOSE

To evaluate the incidence, morphology, and associated complications of medial cortical hinge fractures after lateral closing wedge distal femoral osteotomy (LCW-DFO) for varus malalignment and to identify constitutional and technical factors predisposing for hinge fracture and consecutive complications.

METHODS

Seventy-nine consecutive patients with a mean age of 47 ± 12 years who underwent LCW-DFO for symptomatic varus malalignment at the authors' institution between 01/2007 and 03/2018 with a minimum of 2-year postoperative time interval were enrolled in this retrospective observational study. Demographic and surgical data were collected. Measurements evaluating the osteotomy cut (length, wedge height, hinge angle) and the location of the hinge (craniocaudal and mediolateral orientation, relation to the adductor tubercle) were conducted on postoperative anterior-posterior knee radiographs and the incidence and morphology of medial cortical hinge fractures was assessed. A risk factor analysis of constitutional and technical factors predisposing for the incidence of a medial cortical hinge fracture and consecutive complications was conducted.

RESULTS

The incidence of medial cortical hinge fractures was 48%. The most frequent morphological type was an extension fracture type (68%), followed by a proximal (21%) and distal fracture type (11%). An increased length of the osteotomy in mm (53.1 ± 10.9 vs. 57.7 ± 9.6; p = 0.049), an increased height of the excised wedge in mm (6.5 ± 1.9 vs. 7.9 ± 3; p = 0.040) as well as a hinge location in the medial sector of an established sector grid (p = 0.049) were shown to significantly predispose for the incidence of a medial cortical hinge fracture. The incidence of malunion after hinge fracture (14%) was significantly increased after mediolateral dislocation of the medial cortical bone > 2 mm (p < 0.05).

CONCLUSION

Medial cortical hinge fractures after LCW-DFO are a common finding. An increased risk of sustaining a hinge fracture has to be expected with increasing osteotomy wedge height and a hinge position close to the medial cortex. Furthermore, dislocation of a medial hinge fracture > 2 mm was associated with malunion and should, therefore, be avoided.

LEVEL OF EVIDENCE

Prognostic study; Level IV.

Orientation and end zone of the osteotomy cut for high tibial osteotomy: Influence on the risk of lateral hinge fracture. A finite element analysis

INTRODUCTION

the hinge plays a fundamental role in the support and consolidation of a high tibial osteotomy. The objective of this work was to analyse the influence of the end zone of the osteotomy cut and its orientation in relation to the articular joint line (JL) on the risk of hinge fracture.

HYPOTHESIS

a specific orientation and end zone of the osteotomy cut can be utilised to decrease the risk of hinge fracture.

MATERIAL AND METHOD

a finite element (FE) model was used to reproduce the proximal portion of the tibia and the proximal tibiofibular joint with transverse isotropic elastic bone properties. A 1.27mm thick, complete, anteroposterior saw cut was made with a U-shaped saw blade. Five proximal and lateral tibial zones were used according to Nakamura et al corresponding to the end zones of the osteotomy cut. Three angulations of the cut relative to the JL were defined: 10°, 15°, 20°. The tests consisted of simulating 15 possible situations (3 angulations for each of the 5 end zones) on this model. These simulations made it possible to identify the existence of a local stress concentration (von Mises, in MPa) at the level of the hinge, corresponding to the main judgment criterion.

RESULTS

If we consider only the end zones of the osteotomy cut, regardless of its angulation with respect to the JL, the zone which presents, on average, the lowest local stress concentration is the AM zone (40.3MPa). If we consider only the angulation of the osteotomy cut, with respect to the JL, regardless of the end zone of the cut, the angulation that locally concentrates, on average, the least stress is an angulation at 10° (147.7MPa). Finally, it is important to define the best end zone of the osteotomy cut for each angulation value in relation to the JL: for an angulation of 10°, the end zone must be in AM (38MPa), but also for an angulation of 15° (45MPa), and for an angulation of 20° (38MPa).

DISCUSSION-CONCLUSION

With the inherent caveats of the experimental conditions, the hypothesis is confirmed. An end zone of the osteotomy cut exists (AM) and an orientation (10°) that induces the lowest local stress concentration and therefore the least likely to induce lateral hinge fracture. However, the orientation of the osteotomy cut is also a matter of surgical habit, especially regarding complementary osteotomy of the tibial tuberosity that some may want to avoid. Thus, it is equally important to know the best end zone associated with a given angulation of the cut in relation to the JL, which according to these results is the AM zone for each angulation. This information helps guide the operator in their surgical practices according to their habits.

LEVEL OF EVIDENCE

V, expert opinion.

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.

Alignment adjustment using the Valgus stress technique can increase the surgical accuracy of novice surgeons during medial opening-wedge high Tibial osteotomy

Background

The purpose of this study was to compare the degree of accuracy of coronal alignment correction with use of the “alignment adjustment under valgus stress technique” between expert and novice surgeons during medial opening-wedge high tibial osteotomy (MOWHTO).

Methods

Forty-eight patients who underwent MOWHTO performed by an expert surgeon (expert group) and 29 by a novice surgeon (novice group) were enrolled in analysis. During surgery, lower-extremity alignment was corrected using the “alignment adjustment under valgus stress technique”. Normocorrection was defined as a weight-bearing line ratio between 55 and 70% and the correction accuracy was compared between expert and novice groups using the ratio of normocorrection to outliers. The clinical outcomes were also compared using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 1 year after surgery.

Results

The undercorrection rate was 14.6% in the expert group and 13.8% in the novice group, while the overcorrection rate was 2.1% in the expert group and 3.4% in the novice group. In the ratio of normocorrection to outliers, no difference was found between the two groups at the one-year follow-up visit (83.3% in the expert group vs. 82.8% in the novice group; p > 0.05). Also, no significant differences were seen in WOMAC subscores immediately preoperatively and at 1 year after surgery (all p > 0.05).

Conclusion

Adhering to the “alignment adjustment under valgus stress technique” protocol enabled novice surgeons to achieve similar surgical accuracy as that of an expert surgeon in coronal alignment during MOWHTO.

Level of evidence

Level III.

Osteotomy around the knee is planned toward an anatomical bone correction in less than half of patients

INTRODUCTION

In cases where the femur or tibial deformity is not correctly analysed, the corrective osteotomies may result in an oblique joint line. The aim of this study was to assess the preoperative deformity of patients due to undergo corrective osteotomy and the resulting abnormal tibial and femoral morphologies after the planned correction using 3D software.

METHODS

CT scans of 327 patients undergoing corrective osteotomy were retrospectively included. Each patient was planned using a software application and the simulated correction was validated by the surgeon. Following the virtual osteotomy, tibial and femoral coronal angular values were considered abnormal if the values were outside 97.5% confidence intervals for non-osteoarthritis knees. After virtual osteotomy, morphological abnormalities were split into two types. Type 1 was an under/overcorrection at the site of the osteotomy resulting in abnormal bone morphology. A type 2 was defined as an error in the site of the correction, resulting in an uncorrected abnormal bone morphology.

RESULTS

The global rate of planned abnormalities after tibial virtual osteotomy was 50.7% (166/327) with abnormalities type 1 in 44% and type 2 in 6.7%. After femoral virtual osteotomy the global rate was 6.7% (22/327) with only abnormalities type 1. A lower preoperative HKA was significantly associated with a non-anatomical correction (R²=0.12, p<0.001) for both femoral (R²=0.06, p<0.001) and tibial (R²=0.07, p<0.001) abnormalities.

CONCLUSION

Non-anatomical correction was found in more than half the cases analysed more frequently for preoperative global varus alignment. These results suggest that surgeons should considered anatomical angular values to avoid joint line obliquity.

LEVEL OF EVIDENCE

III; retrospective cohort study.