Patient-specific high-tibial osteotomy's 'cutting-guides' decrease operating time and the number of fluoroscopic images taken after a Brief Learning Curve

Combined Correction of Coronal and Rotational Deformities of the Femur With Distal Femoral Osteotomy Using Patient-Specific Instrumentation

BACKGROUND

Distal femoral osteotomy (DFO) can be used to simultaneously correct coronal and rotational deformities. Patient-specific instruments (PSIs) are known to be helpful in such complex osteotomies, but data on surgical accuracy for the combined correction of coronal and rotational deformities of the femur are missing.

PURPOSE

To investigate the radiological results of DFO for simultaneous correction of coronal and rotational deformities using PSIs.

STUDY DESIGN

Case series; Level of evidence, 3.

METHODS

All included patients underwent DFO (34 patients, 36 knees) using PSIs for combined correction of coronal and rotational deformities. The hip-knee-ankle angle (HKA) was measured in weightbearing long-leg radiographs, and the femoral torsion was assessed using computed tomography scans, both pre- and postoperatively. The achieved corrections of HKA and femoral torsion were determined for each knee, and surgical accuracy was calculated.

RESULTS

HKA and femoral torsion changed significantly from preoperatively to postoperatively (from 2.4° ± 3.6° vs 0.1° ± 1.8° [P < .001] and 31.2° ± 17.2° vs 18.7° ± 7.4° [P < .001]). The difference from planned to achieved correction was statistically greater for HKA (-2.9° ± 3.8° vs -2.3° ± 3.5°; P = .018) than for femoral torsion (-12.4° ± 11.8° vs -12.3° ± 12.2°; P = .771), which did not reach significance. The accuracies of HKA and femoral torsion correction were 1.1° ± 1° and 2.4° ± 1.9°, respectively.

CONCLUSION

Coronal and rotational deformities of the femur can accurately be corrected simultaneously by a DFO, utilizing PSIs. High accuracy was achieved for the correction of both coronal and rotational deformities, with absolute mean differences from planned to achieved correction of 1.1° and 2.4°, respectively.

Anterior tibial tubercle internal torsion osteotomy (ATTITO) in patient with patellar instability

Anterior tibial tuberosity osteotomy is a well-described therapeutic option for the treatment of patellar instability. External torsion of the anterior tibial tuberosity can be one of several factors that adversely affect the patellofemoral joint and its stability. The Anterior Tibial Tubercle Internal Torsion Osteotomy (ATTITO) allows the correction of excessive external torsion of the tibial tuberosity in a safe and reproducible manner. LEVEL OF EVIDENCE: V.

Patient-specific cutting guides allow 1° precision in asymmetric anterior closing-wedge osteotomy

Purpose

Asymmetric anterior closing-wedge high tibial osteotomy (ACWHTO) allows correction of both excessive posterior tibial slope (PTS) and varus deformity. However, the complexity of this surgery requires a high degree of accuracy, which is less likely to be achieved with standard instrumentations. This study aimed to determine the accuracy of 3D patient-specific cutting guides (PSCGs) to provide the accurate planned correction in the frontal and sagittal planes.

Methods

Eight sawbones tibiae were identically printed from the same patient data. An ACWHTO with a PSCG was performed on each sawbone. Postoperative measurements of PTS, mechanical medial proximal tibial angle (mMPTA), hinge area and hinge-posterior cruciate ligament (hinge-PCL) distance were compared with the preoperative planned measurements. The precision was defined as the absolute difference (∆) between the target planned values and postoperative values.

Results

The mean accuracy was 0.6° ± 0.74° for PTS, 0.8° ± 0.71° for mMPTA, 0.3 ± 0.2 cm2 for hinge area and 0.1 ± 0.06 mm for hinge-PCL distance.

Conclusion

In the setting of sawbones, the use of PSCGs was a reliable and accurate method of achieving simultaneous correction in the frontal and sagittal planes during asymmetric ACWHTO.

Level of Evidence

Level V, basic science biomechanical laboratory study.

Optimizing Reduction Guide Stability in Osteotomy Using Patient-Specific Instrumentation: A Basic Guideline

Background

The use of patient-specific instruments (PSIs) for osteotomies is becoming more popular in orthopaedic surgery for correcting mechanical axis and posttraumatic deformities. However, the PSI reduction guides have great potential for intraoperative deformation, which adversely affects the accuracy of the procedure.

Purpose

To conduct a finite element analysis (FEA) to analyze different design parameters to improve the intraoperative stability of the reduction guides.

Study Design

Descriptive laboratory study.

Methods

A reduction guide with a rectangular cross section and four 4-mm K-wire slots was simplified, and the following parameters were modified: width, height, profile design, K-wire thickness, and positions. Bending and torsional moments were applied to the guide construct and guide deformation and equivalent stress were determined using FEA.

Results

Increasing the profile height by 25% resulted in a 44% reduction in guide deformation for bending (37% for torsion). A 25% increase in profile width led to an 18% deformation reduction for bending (22% for torsion). Transverse K-wire slots resulted in 51% less deformation in torsion compared with longitudinally oriented slots. Placing the central K-wire slots 25% closer to the osteotomy reduced guide deformation by 20% for bending and 11% for torsion.

Conclusion

The most effective methods to increase reduction guide stability are to increase the guide height and reduce the central K-wire distance to the osteotomy.

Clinical Relevance

When performing opening or closing wedge osteotomies, which mainly involve bending of the guide, a high-profile guide and longitudinally oriented K-wire slots should be used. When torque is expected as in rotational osteotomies, the K-wire holes in guides should be oriented transversely to reduce intraoperative deformation.

Accuracy of Combined High Tibial Slope Correction Osteotomy Using 3-Dimensional-Planned Patient-Specific Instrumentation

BACKGROUND

If an increased posterior tibial slope (PTS) and concomitant unicompartmental osteoarthritis are present, a simultaneous sagittal (slope) and coronal correcting high tibial osteotomy has been recommended. However, no study has investigated the accuracy of such combined high tibial slope correction osteotomies.

PURPOSE

(1) To report the accuracy of navigated high tibial slope correction osteotomies using patient-specific instruments (PSI) and (2) to analyze the influence of an open wedge osteotomy (OWO) versus a closed wedge osteotomy (CWO) and the hinge axis angle (HAA) on the accuracy of the PTS correction.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

All PSI PTS-reducing osteotomies performed at 1 institution between 2019 and 2022 were reviewed. Three-dimensional (3D) accuracy was defined as the mean absolute 3D angular difference between the planned and achieved surgical correction (in degrees) in 3D models of computed tomography data. The influence of OWO versus CWO and the HAA on the reported accuracy was analyzed and a cutoff defined using receiver operating characteristic curve analysis.

RESULTS

Eighteen patients who underwent a slope-reducing CWO (n = 9) or OWO (n = 9) were included. The 3D accuracy for PTS was 2.3°± 1.1° (mean ± SD), with CWO being more accurate than OWO (1.4°± 0.9° vs 3.1°± 0.6°; P < .01). Accuracy strongly correlated with the HAA (r = 0.788; P < .01). An HAA >38.9° predicted a PTS error >2° (odds ratio, 1.12 [95% CI, 1.04-1.20; P = .004]; area under the curve, 0.95 [95% CI, 0.89-1.00; P < .001]) corresponding to a coronal/sagittal correction of 0.8:1.

CONCLUSION

Slope-reducing osteotomy can accurately be achieved using PSI. CWO demonstrated an increased accuracy when compared with OWO, which strongly depended on the HAA. With an aim of combined PTS and coronal correction, CWO should be considered the primary choice for accurate slope reduction with a coronal/sagittal correction cutoff of 0.8:1 (HAA, 38.9°).

Learning curves for high tibial osteotomy using patient-specific instrumentation: a case control study

Objectives

Three-dimensional (3D) planning and Patient Specific Instrumentation (PSI) can help the surgeon to obtain more predictable results in Medial Opening Wedge High Tibial Osteotomy (mOW-HTO) than the conventional techniques. We compared the accuracy of the PSI and standard techniques and measured the learning curve for surgery time and number of fluoroscopic shots.

Methods

We included the first 12 consecutive cases of mOW-HTO performed with 3D planning and PSI cutting guides and the first 12 non-supervised mOW-HTO performed with the standard technique. We recorded surgery time and fluoroscopic time. We calculated the variation (Δ delta) between the planned target and the postoperative result for Hip Knee Ankle Angle (HKA), mechanical medial Proximal Tibia Angle (MPTA), Joint Line Convergence Angle (JLCA) and tibial slope (TS) and compared it both groups. We also recorded the complication rate. We then calculated the learning curves for surgery time, number of fluoroscopic shots, Δ from target in both groups. CUSUM analysis charts for learning curves were applied between the two groups.

Results

Mean surgical time and mean number of fluoroscopic shots were lower in PSI group (48.58±7.87 vs. 58.75±6.86 min; p=0.034 and 10.75±3.93 vs. 18.16±4.93 shots; p<0.001). The postoperative ΔHKA was 0.42±0.51° in PSI vs. 1.25±0.87° in conventional, p=0.005. ΔMPTA was 0.50±0.67° in PSI vs. 3.75±1.48° in conventional, p<0.001; ΔTS was 1.00±0.82° in PSI vs. 3.50±1.57° in conventional, p<0.001. ΔJLCA was 1.83±1.11° in PSI vs. 4±1.41° in conventional, p<0.001. The CUSUM analysis favoured PSI group regarding surgery time (p=0.034) and number of shots (p<0.001) with no learning curve effect for ΔHKA, ΔMPTA, ΔJLCA and ΔTS.

Conclusions

PSI cutting guides and 3D planning for HTO are effective in reducing the learning curves for operation time and number of fluoroscopic shots. Accuracy of the procedure has been elevated since the first cases.

Clinical outcomes of guider-assisted osteotomy compared to conventional pendulum-saw osteotomy in open wedge high tibial osteotomy: a propensity score-matched cohort study

PURPOSE

We developed a novel guider-assisted osteotomy (GAO) procedure to improve the safety of open wedge high tibial osteotomy (OWHTO) and aimed to compare its efficacy and complications with the conventional pendulum-saw osteotomy (PSO).

METHODS

This is a retrospective cohort study of patients undergoing either GAO or PSO procedure in the OWHTO to treat varus knee osteoarthritis, who had a minimum of 2 years of follow-up. Patients were propensity score matched (PSM) in a 1:1 ratio based on demographic and clinical data with a caliper width of 0.02. The outcomes assessed involved the hospital for special surgery (HSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, and the Intraoperative and postoperative complications.

RESULTS

199 patients were included in each group after PSM. The mean duration of follow-up was 38.3 ± 8.9 months. The GAO group had a shorter operation duration (104.5 ± 35.7 vs. 112.1 ± 36.0 min, p = 0.027) and fewer times of intraoperative fluoroscopy (4.2 ± 1.4 vs. 6.0 ± 1.4, p < 0.001). At the last follow-up, clinical scores for knee achieved significant improvements in both GAO and PSO groups: HSS (67.5 ± 10.5 vs. 90.2 ± 7.0, p < 0.001; 69.4 ± 8.2 vs. 91.7 ± 6.8, p < 0.001) and WOMAC (65.7 ± 11.6 vs. 25.2 ± 10.4, p < 0.001; 63.3 ± 12.2 vs. 23.8 ± 9.5, p < 0.001). However, no significant difference was observed between groups for any measures (p > 0.05). In addition, the intraoperative complications (0.5% vs. 3.5%, p = 0.068) and the postoperative bone delayed union and nonunion (1.0% vs. 4.5%, p = 0.032) were marginally or significantly reduced in the GAO versus PSO group.

CONCLUSION

GAO demonstrates improvements in intraoperative radiation exposure and complications, with comparable short-term efficacy to PSO, and could be considered a viable alternative in clinical practice.

Applications and accuracy of 3D-printed surgical guides in traumatology and orthopaedic surgery: A systematic review and meta-analysis

Background

Patient-Specific Surgical Guides (PSSGs) are advocated for reducing radiation exposure, operation time and enhancing precision in surgery. However, existing accuracy assessments are limited to specific surgeries, leaving uncertainties about variations in accuracy across different anatomical sites, three-dimensional (3D) printing technologies and manufacturers (traditional vs. printed at the point of care). This study aimed to evaluate PSSGs accuracy in traumatology and orthopaedic surgery, considering anatomical regions, printing methods and manufacturers.

Methods

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Studies were eligible if they (1) assessed the accuracy of PSSGs by comparing preoperative planning and postoperative results in at least two different planes (2) used either computer tomography or magnetic resonance imaging (3) covered the field of orthopaedic surgery or traumatology and (4) were available in English or German language. The 'Quality Assessment Tool for Quantitative Studies' was used for methodological quality assessment. Descriptive statistics, including mean, standard deviation, and ranges, are presented. A random effects meta-analysis was performed to determine the pooled mean absolute deviation between preoperative plan and postoperative result for each anatomic region (shoulder, hip, spine, and knee).

Results

Of 4212 initially eligible studies, 33 were included in the final analysis (8 for shoulder, 5 for hip, 5 for spine, 14 for knee and 1 for trauma). Pooled mean deviation (95% confidence interval) for total knee arthroplasty (TKA), total shoulder arthroplasty (TSA), total hip arthroplasty (THA) and spine surgery (pedicle screw placement during spondylodesis) were 1.82° (1.48, 2.15), 2.52° (1.9, 3.13), 3.49° (3.04, 3.93) and 2.67° (1.64, 3.69), respectively. Accuracy varied between TKA and THA and between TKA and TSA.

Conclusion

Accuracy of PSSGs depends on the type of surgery but averages around 2-3° deviation from the plan. The use of PSSGs might be considered for selected complex cases.

Level of Evidence

Level 3 (meta-analysis including Level 3 studies).

3D osteotomies-improved accuracy with patient-specific instruments (PSI)

PURPOSE

Three-dimensional (3D) printed patient-specific instruments (PSI) have been introduced to increase precision and simplify surgical procedures. Initial results in femoral and tibial osteotomies are promising, but validation studies on 3D planning, manufacturing of patient-specific cutting blocks and 3D evaluation of the attained results are lacking.

METHODS

In this study, patient-specific cutting blocks and spacers were designed, fabricated, and used to perform a high tibial osteotomy (HTO). After segmentation of CT data sets from 13 human tibiae, 3D digital planning of the HTO was performed with a medial opening of 8 mm. These 3D models were used to fabricate patient-specific cutting blocks and spacers. After the surgical procedure, accuracy was evaluated measuring 3D joint angles and surface deviations.

RESULTS

The lowest mean deviation was found to be 0.57° (SD ± 0.27) for the MPTA. Medial and lateral tibial slope deviated from the 3D planning by an average of 0.98° (SD ± 0.53) and 1.26° (SD ± 0.79), respectively, while tibial torsion deviated by an average of 5.74° (SD ± 3.24). Color analysis of surface deviations showed excellent and good agreement in 7 tibiae.

CONCLUSION

With 3D cutting blocks and spacers, the 3D planning of the HTO can be translated into reality with small deviations of the resulting joint angles. Within this study, the results of the individual steps are examined for errors and thus a critical evaluation of this new and promising method for performing patient-specific HTOs is presented.

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

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

Management of Anxiety for Ambulatory Hallux Valgus Surgery With a Virtual Reality Hypnosis Mask: Randomized Controlled Trial

BACKGROUND

The purpose of this study was to evaluate the impact of using virtual reality masks for the management of preoperative anxiety and its impact on postoperative and predischarge anxiety as well as postoperative analgesia during outpatient hallux valgus surgery.

METHODS

From June 2020 to September 2021, preoperative anxiety of patients scheduled for a percutaneous hallux valgus surgery were analyzed using the State Trait Anxiety Inventory (STAI) questionnaire completed during the consultation. All patients with major anxiety, defined as a STAI score above 40, were included in a randomized prospective comparative single-center study. Sixty patients were included in the study and randomized into 2 arms of 30 patients according to whether or not they underwent a preoperative hypnosis session with a virtual reality mask before surgery.

RESULTS

There was an improvement in the postoperative (42.5 vs 45.2, P < .04) and predischarge (25.3 vs 30.2 P < .03) anxiety scores in the group that used the mask before the procedure. There was a notable decrease in immediate higher-level postoperative analgesics such as morphine or ketamine (3.3% vs 26.6%, P < .03) in the arm using the mask.

CONCLUSION

In this study cohort undergoing percutaneous hallux valgus surgery, we found that use of a virtual reality hypnosis mask before surgery modestly reduced postoperative and predischarge anxiety as well as early postoperative consumption of higher-level analgesics in adults with significant preoperative anxiety.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Patient-specific instrumentation for medial opening wedge high tibial osteotomies in the management of medial compartment osteoarthritis yields high accuracy and low complication rates: A systematic review

IMPORTANCE

There has been growing interest in the use of patient-specific instrumentation (PSI) to maximise accuracy and minimise the risk of major complications for medial opening-wedge high tibial osteotomies (MOW-HTOs). Numerous studies have reported the efficacy and safety of implementing this technology into clinical practice, yet no systematic review summarising the clinical literature on PSI for MOW-HTOs has been performed to date.

AIM

The aim of this investigation was to perform a systematic review summarising the evidence surrounding the use of PSI for MOW-HTOs in the management of medial compartment osteoarthritis.

EVIDENCE REVIEW

PubMed, Scopus, and the Cochrane Library were queried in October 2021 for studies that used PSI for MOW-HTOs when managing medial compartment knee osteoarthritis. Primary outcomes included accuracy in coronal plane correction (mechanical medial proximal tibial angle), sagittal plane correction (posterior tibial slope), and mechanical axis correction (hip-knee-ankle angle [HKA], mechanical femorotibial angle, and weight-bearing line). Accuracy was defined as error between post-operative measurements relative to the planned pre-operative correction. A secondary outcome was the incidence of major complications.

FINDINGS

This review included eight different techniques among the 14 included studies. There was a weighted mean error of 0.5° (range: 0.1°-1.3°) for the mechanical medial proximal tibial angle, 0.6° (range: 0.3°-2.7°) for the posterior tibial slope, and 0.8° (range: 0.1°-1.0°) for the hip-knee-ankle angle. Four studies compared the correctional error of the mechanical axis between conventional techniques and PSI techniques. The comparative difference between the two techniques favoured the use of PSI for MOW-HTOs (standardised mean difference ​= ​0.52; 95% confidence interval, 0.16 to 0.87; p ​= ​0.004). Among the 14 studies evaluated, four studies explicitly reported no major complications, while five studies reported a non-zero incidence of major complications. Among these nine studies, the weighted mean major complication rate was 7.1% (range: 0.0-13.0%).

CONCLUSIONS AND RELEVANCE

The findings of this present systematic review suggest that the use of PSI for MOW-HTOs leads to high accuracy relative to the planned corrections in the coronal plane, sagittal plane, and mechanical axis. Furthermore, these findings would suggest there is a low risk of major complications when implementing PSI for MOW-HTOs.

LEVEL OF EVIDENCE

Systematic review; IV.

Automatic Assessment of Lower-Limb Alignment from Computed Tomography

BACKGROUND

Preoperative planning of lower-limb realignment surgical procedures necessitates the quantification of alignment parameters by using landmarks placed on medical scans. Conventionally, alignment measurements are performed on 2-dimensional (2D) standing radiographs. To enable fast and accurate 3-dimensional (3D) planning of orthopaedic surgery, automatic calculation of the lower-limb alignment from 3D bone models is required. The goal of this study was to develop, validate, and apply a method that automatically quantifies the parameters defining lower-limb alignment from computed tomographic (CT) scans.

METHODS

CT scans of the lower extremities of 50 subjects were both manually and automatically segmented. Thirty-two manual landmarks were positioned twice on the bone segmentations to assess intraobserver reliability in a subset of 20 subjects. The landmarks were also positioned automatically using a shape-fitting algorithm. The landmarks were then used to calculate 25 angles describing the lower-limb alignment for all 50 subjects.

RESULTS

The mean absolute difference (and standard deviation) between repeat measurements using the manual method was 2.01 ± 1.64 mm for the landmark positions and 1.05° ± 1.48° for the landmark angles, whereas the mean absolute difference between the manual and fully automatic methods was 2.17 ± 1.37 mm for the landmark positions and 1.10° ± 1.16° for the landmark angles. The manual method required approximately 60 minutes of manual interaction, compared with 12 minutes of computation time for the fully automatic method. The intraclass correlation coefficient showed good to excellent reliability between the manual and automatic assessments for 23 of 25 angles, and the same was true for the intraobserver reliability in the manual method. The mean for the 50 subjects was within the expected range for 18 of the 25 automatically calculated angles.

CONCLUSIONS

We developed a method that automatically calculated a comprehensive range of 25 measurements that defined lower-limb alignment in considerably less time, and with differences relative to the manual method that were comparable to the differences between repeated manual assessments. This method could thus be used as an efficient alternative to manual assessment of alignment.

LEVEL OF EVIDENCE

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

Patient Specific Instruments and Patient Individual Implants—A Narrative Review

Joint arthroplasties are one of the most frequently performed standard operations worldwide. Patient individual instruments and patient individual implants represent an innovation that must prove its usefulness in further studies. However, promising results are emerging. Those implants seem to be a benefit especially in revision situations. Most experience is available in the field of knee and hip arthroplasty. Patient-specific instruments for the shoulder and upper ankle are much less common. Patient individual implants combine individual cutting blocks and implants, while patient individual instruments solely use individual cutting blocks in combination with off-the-shelf implants. This review summarizes the current data regarding the implantation of individual implants and the use of individual instruments.

Double-level knee osteotomy accurately corrects lower limb deformity and provides satisfactory functional outcomes in bifocal (femur and tibia) valgus malaligned knees

PURPOSE

Double-level knee osteotomy (DLO) is a challenging procedure that requires precision in preoperative planning and intraoperative execution to achieve the desired correction. It is indicated in cases of severe varus or valgus deformities where a single-level osteotomy would yield significantly tilted joint line obliquity (JLO). This study aimed to evaluate the effectiveness of DLO in achieving accurate correction without compromising JLO, using patient-specific cutting guides (PSCGs), in cases of bifocal valgus maligned knees.

METHODS

A single-centre, retrospective analysis of prospectively collected data for a total of 26 patients, who underwent DLO by PSCGs for valgus malaligned knees, between 2015 and 2020. Post-operative alignment was evaluated and the delta for different lower limb0.05, not statistically significant (ns)). All KOOS subs alignment parameters was calculated; the hip-knee-ankle angle (ΔHKA), medial proximal tibial angle (ΔMPTA), and lateral distal femoral angle (ΔLDFA). At the two-year follow-up, changes in the KOOS sub-scores, UCLA scores, lower limb discrepancy (LLD), and mean time to return to work and sport were recorded. All intraoperative and postoperative complications were recorded. The Mann-Whitney U test with a 95% confidence interval (95% CI) was used to evaluate the differences between two variables; one-way ANOVA between more than two variables and the paired Student's t-test was used to estimate the evolution of functional outcomes.

RESULTS

The postoperative mean ΔHKA was 0.9 ± 0.9°, the mean ΔMPTA was 0.7 ± 0.7°, and the mean ΔLDFA was 0.7 ± 0.8° (all values with p > 0.05, not statistically significant (ns)). All KOOS subscore's mean values were improved to an extent two-fold superior to the reported minimal clinically important difference (MCID) (all with p < 0.0001). There was a significant increase in the UCLA score at the final follow-up (5.4 ± 1.5 preoperatively versus 7.7 ± 1.4, p < 0.01). The mean time to return to sport and work was 4.7 ± 1.1 and 4.3 ± 2.1 months, respectively. There was an improvement in Lower-limb discrepancy preoperative (LLD = 1.3 ± 2 cm) to postoperative measures (LLD = 0.3 ± 0.4 cm), ns. Complications were 2 femoral hinge fractures, 2 deep vein thromboses, 1 delayed tibial healing, and 1 hardware removal for hamstring irritation syndrome.

CONCLUSION

DLO is effective and safe in achieving accurate correction in bifocal valgus malaligned knees with maintained lower limb length and low complication rate with no compromise of JLO.

LEVEL OF EVIDENCE

III.

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.

Comparison of Clinical and Radiological Outcomes between Calibratable Patient-Specific Instrumentation and Conventional Operation for Medial Open-Wedge High Tibial Osteotomy: A Randomized Controlled Trial

BACKGROUND

High tibial osteotomy (HTO) is an effective surgery in treating medial compartment knee osteoarthritis (KOA) combined with varus deformity. An accurate orthopaedy is the key and challenge to the success of HTO. Therefore, we designed a calibratable patient-specific instrumentation (PSI) to assist surgery and evaluated its accuracy and clinical outcomes by comparing with conventional operation (CO).

MATERIALS AND METHODS

37 patients (39 knees) with medial compartment KOA were randomly divided into the PSI and CO groups and underwent medial open-wedge high tibial osteotomy (MOWHTO) from September 2020 to May 2021. The postoperative radiological outcomes were compared with the preoperative measurements or target values to evaluate the accuracy of correction in the two groups. The American Knee Society Score (AKSS), complication rate, number of intraoperative radiation exposures, blood loss volume, and operative duration were analysed to evaluate the clinical outcomes in the two groups.

RESULTS

The designed target values were better achieved in the PSI group than in the CO group. The mean absolute difference between the postoperative measurements and preoperative targets was significantly lower in the PSI group than in the CO group (weight-bearing line (WBL) ratio, 1.97 ± 1.83% vs.5.42 ± 4.41%, P = 0.002; hip-knee-ankle (HKA) angle, 1.12 ± 0.86° vs. 2.27 ± 1.97°, P = 0.018). The operative duration was significantly shorter (P = 0.014), and the number of radiation exposures (P < 0.001) and volume of intraoperative blood loss (P = 0.003) were significantly lower in the PSI group than in the CO group. The clinical AKSS score at 3 and 6 months postoperatively and the functional AKSS score at 3 months postoperatively were significantly higher in the PSI group than in the CO group (P = 0.042, 0.040, and 0.034, respectively).

CONCLUSION

For patients with medial compartment KOA, calibratable PSI can assist the surgeon in MOWHTO with superior accuracy and clinical efficacy. This study was conducted under Randomized Controlled Trial Details (RCT) with Registry Number ChiCTR2000038619.

Pre-surgery HKA angle and WBL percentage are nearly perfectly correlated to the Miniaci angle when planning open wedge high tibial osteotomies

PURPOSE

To investigate the conversion formulas between the Miniaci angle, pre-surgery parameters, and changes in pre-surgery parameters in open-wedge high tibial osteotomy (OWHTO), including hip-knee-ankle (HKA) angle, weight-bearing line (WBL) percentage, mechanical medial proximal tibial angle (mMPTA), ΔHKA angle, ΔWBL percentage, ΔmMPTA, and other parameters.

METHODS

From January 2012 to December 2019, 247 lower limbs of 144 patients with medial unicompartmental knee osteoarthritis combined with proximal tibia vara were enrolled. Inclusion criteria were adults, medial unicompartmental knee osteoarthritis, Kellgren-Lawrence classification grade ≤ Ⅲ, mMPTA ≤85° and mechanical lateral distal femoral angle (mLDFA) is normal (85°-90°), and patella facing anterior in the bipedal standing position. Exclusion criteria were history of fracture, trauma, or orthopaedic surgery; developmental dysplasia of the hip or femoral head necrosis; femoral bowing deformity; deformity of the tibial shaft; and leg length discrepancy. Using standing whole-leg radiographs (WLRs), an OWHTO simulation was performed to determine the Miniaci angle by delivering the WBL to the Fujisawa point. The relationship of the Miniaci angle, the pre-surgery parameters, and the changes in pre-surgery parameters were analysed by spearman's correlation and linear regression analyses. The relationship between the post-surgery HKA angle and pre-surgery parameters was analysed by multiple linear regression model.

RESULTS

The Miniaci angle showed a near perfect correlation with the pre-surgery HKA angle (y=-1.05x+192.10, r²=0.99), pre-surgery WBL percentage (y=-0.25x+15.14, r²=0.97), ΔHKA angle (y=1.04x-0.03, r²=1.00), ΔWBL percentage (y=0.25x-0.52, r²=0.97), and ΔmMPTA (y=1.04x-0.03, r²=1.00). The ΔHKA angle showed nearly perfect correlation with the ΔmMPTA (y=1.00x, r²=1.00), and ΔWBL percentage (y=0.24x-0.47, r²=0.97).

CONCLUSIONS

The pre-surgery HKA angle, pre-surgery WBL percentage, ΔHKA angle, ΔWBL, and ΔmMPTA percentage are nearly perfectly correlated to the Miniaci angle, while the ΔmMPTA and ΔWBL percentage are nearly perfectly correlated to the ΔHKA angle.

CLINICAL RELEVANCE

With the conversion formulas determined in the current study, surgeons can calculate the Miniaci angle based on the pre-surgery parameters without the assistance of digital software for complex surgical simulation. The Miniaci angle is closely related to the gap of the medial opening wedge. Based on the Miniaci angle and the depth of the osteotomy, surgeons can calculate the gap required prior to surgery using trigonometric functions and then simply measure the gap during surgery.

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.

Anterior Closing-Wedge High Tibial Osteotomy Using Patient-Specific Cutting Guide in Chronic Anterior Cruciate Ligament-Deficient Knees

An increased posterior tibial slope has been identified as an independent risk factor for anterior cruciate ligament (ACL) graft rupture, with a critical threshold of 12°. Surgical slope correction by anterior closing wedge (ACW)-high tibial osteotomy (HTO) can reduce ACL force and anterior tibial translation with good clinical outcomes when combined with revision ACL reconstruction. Performing ACW-HTO preserving the tibial tubercule can be challenging for inexperienced surgeons. Patient-specific cutting guides have been shown to be effective in facilitating the surgeon's learning curve in medial opening wedge-HTO by reducing operative time and the use of fluoroscopy as well as decreasing anxiety. The present technique describes a retro-tibial tubercule ACW-HTO using a patient-specific cutting guide.

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.

Global varus malalignment increase from double-leg to single-leg stance due to intra-articular changes

PURPOSE

Preoperatively planned correction for tibial osteotomy surgery is usually based on weightbearing long-leg Xrays, while the surgery is performed in a supine non-weightbearing position. The purpose of this study was to assess the differences in lower limb alignment in three different weightbearing conditions: supine position, double-leg (DL) stance and single-sleg (SL) stance prior to performing a medial opening wedge high tibial osteotomy (MOWHTO) for varus malalignment. The hypothesis of this study was that progressive limb-loading would lead to an increased preoperative varus deformity.

MATERIAL AND METHODS

This retrospective study included 89 patients (96 knees) with isolated medial knee osteoarthritis (Ahlbäck grade I or II) and significant metaphyseal tibial vara (> 6°). The differences between supine position, DL stance and SL stance were analysed for the hip-knee-ankle angle (HKA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), weight-bearing line ratio (WBL) and joint line convergence angle (JLCA).

RESULTS

From a supine position to DL stance, the HKA angle slightly increased from 175.5° ± 1.1° to 176.3° ± 1.1° and JLCA changed from 2.0° ± 0.3° to 1.8° ± 0.3° without a statistically significant difference. From DL to SL stances, the HKA angle decreased from 176.3° ± 1.1° to 174.4° ± 1.1° (p < 0.05) and the JLCA increased from 1.8° ± 0.3° to 2.6° ± 0.3° (p < 0.05). A significant correlation was found between ΔHKA and ΔJLCA between the DL and the SL stances (R² = 0.46; p = 0.01).

CONCLUSION

Varus malalignment increases with weight-bearing loading from double-leg to single-leg stances with an associated JLCA increase. Thus, single-leg stance radiographs may be useful to correct preoperative planning considering patient-specific changes in JLCA.

LEVEL OF CLINICAL EVIDENCE

III, retrospective comparative study.

CAS and PSI increase coronal alignment accuracy and reduce outliers when compared to traditional technique of medial open wedge high tibial osteotomy: a meta-analysis

PURPOSE

Medial open-wedge high tibial osteotomy (MOWHTO) is an accepted option in the treatment of medial compartment osteoarthritis of the knee in young and active patients. Functional results are closely correlated to the correction of the mechanical axis of the lower limb. Although several angular and geometrical methods and values have been proposed in the past, the ideal target is still debated. In addition, it is important to have a deep correlation between the planned correction and the achieved correction after surgery. The aim of the present systematic review was to identify the ideal coronal correction after MOWHTO and the most accurate method to achieve it.

METHODS

A systematic review of the literature was completed on July 3rd 2020 in the Pubmed, Medline, Cochrane Reviews, and Google Scholar databases using the Medical Subject Headings (MeSH) terms: "high tibial osteotomy" AND "accuracy" OR "planning".

RESULTS

28 studies were included; 18 were focused on computer-assisted surgery (CAS) and 10 on patient-specific instrumentation (PSI). There were 598 patients in the CAS group and 501 in the control group; the rate of outliers was 16% and 38.2% respectively (P = 0.04), while there was no significant difference between the two groups (SMD = - 0.10; 95% CI 1.31 to 1.12; P = n.s.) in terms of coronal accuracy. Likewise, there were 318 patients in the PSI group and 40 in the control group; the rate of outliers was 15% and 40% respectively (P = 0.98), while there was no significant difference between the two groups (SMD = 0.01; 95% CI 0.58 to 0.59; P = 0.98).

CONCLUSIONS

A statistically significant reduced outlier rate and a non-significant increased accuracy emerged with the use of CAS when compared to the traditional surgical technique, whereas the results of PSI were still inconclusive. In addition, it emerged clearly that no consensus still exists on the ideal correction target to be achieved after surgery.

LEVEL OF EVIDENCE

III.

The validity and accuracy of 3D-printed patient-specific instruments for high tibial osteotomy: a cadaveric study

Objective

High tibial osteotomy (HTO) has been used for the treatment of patients with knee osteoarthritis. However, the successful implementation of HTO requires precise intraoperative positioning, which places greater requirements on the surgeon. In this study, we aimed to design a new kind of 3D-printed patient-specific instrument (PSI) for HTO, including a positioning device and an angle bracing spacer, and verify its effectiveness using cadaveric specimens.

Methods

This study included ten fresh human lower-limb cadaveric specimens. Computed tomography (CT) and X-ray examinations were performed to make preoperative plans. PSI was designed and 3D-printed according to the preoperative plan. Then, the PSI was used to guide HTO. Finally, we performed X-ray and CT after the operation to verify its validity and accuracy.

Results

The PSI using process was adjusted according to the pre-experimental procedure in 1 case. Hinge fracture occurred in 1 case. According to X-rays of the remaining eight cadaveric specimens, no statistically significant difference was noted between the preoperative planning medial proximal tibial angle (MPTA) and postoperative MPTA (P > 0.05) or the preoperative and postoperative posterior slope angle (PSA) (P > 0.05). According to the CT of 10 cadaveric specimens, no statistically significant difference was noted between the design angle and actual angle, which was measured according to the angle between the osteotomized line and the cross section (P > 0.05). The gap between the designed osteotomy line and the actual osteotomy line was 2.09 (0.8 ~ 3.44) mm in the coronal plane and 1.58 (0.7 ~ 2.85) mm in the sagittal plane.

Conclusion

This 3D-printed PSI of HTO accurately achieves the angle and position of the preoperative plan without increasing the stripping area. However, its use still requires a certain degree of proficiency to avoid complications, such as hinge fracture.

Opening Wedge High Tibial Osteotomy with Combined Use of Patient-Specific 3D-Printed Plates and Taylor Spatial Frame for the Treatment of Knee Osteoarthritis

Background

High tibial osteotomy (HTO) is used to treat medial degeneration of the osteoarthritis (OA) knee. However, shortcomings still exist in the current procedure, like unprecise creation, inability to correct knee rotation, and internal fixed failure. Here, we reported a novel procedure: patient-specific 3D-printed plates for opening wedge high tibial osteotomy (OWHTO) combined with Taylor spatial frame (TSF). The detailed technique was described, and the clinical outcomes were evaluated.

Methods

We prospectively evaluate outcomes of patient-specific 3D-printed plates for OWHTO with use of TSF in 25 patients with knee OA and varus alignment. Postoperative efficacy was evaluated using the HSS knee score, pain visual simulation score (VAS), and knee joint motion (ROM), and lower limb alignment was evaluated by measuring femorotibial angle (FTA) and hip-knee-ankle (HKA). Results and Conclusion. All patients did not experience complications such as wound infection, nerve damage, or bone amputation. 25 patients were followed up for 6–18 months. The bony union at bone amputation was achieved in 3 months after surgery, and the pain symptoms were significantly alleviated or disappeared. The VAS score was significantly reduced in 6 months after surgery compared with preoperative; the HSSS score was significantly added in 6 months after surgery compared with preoperative. The ROM of knee joint increased significantly 6 months after operation compared with that before operation, and the difference was statically significant (P < 0.05). The FTA and HKA after operation were significantly superior to that before operation, and the difference was statically significant (P < 0.01).

Conclusions

Our study showed that patient-specific 3D-printed plates for HTO with the use of TSF have the advantages of small trauma, few complications, simple operation, and fast recovery in treating knee OA and varus alignment.

Role of high tibial osteotomy in medial compartment osteoarthritis of the knee: Indications, surgical technique and outcomes

Knee osteoarthritis (OA) is the most common joint disorder worldwide. In particular, primary knee OA often presents with a varus malalignment. This increases the loads going through the medial compartment resulting in cartilage degeneration and symptomatic arthritis. High tibial osteotomy (HTO) is the workhorse surgical procedure for treating medial knee OA. When performed precisely in the hands of an experienced surgeon, HTO can delay or avoid knee arthroplasty. Of note, outcomes of knee arthroplasty are at best unpredictable in patients of younger age. Hence, there is a growing need for joint preservation procedures for younger patients presenting with knee OA, of which HTO is one. Through this article, the authors of whom all are joint preservation surgeons with a special interest in osteotomy hope to share from their experience as well as the available literature on the indications, perioperative planning, surgical technique, outcomes as well as pearls and pitfalls of HTO.

Double level knee osteotomy using patient-specific cutting guides is accurate and provides satisfactory clinical results: a prospective analysis of a cohort of twenty-two continuous patients

PURPOSE

Double level osteotomy (DLO) (femoral and tibial) is a technically demanding procedure for which pre-operative planning accuracy and intraoperative correction are key factors. The aim of this study was to assess the accuracy of the achieved correction using patient-specific cutting guides (PSCGs) compared to the planned correction, its ability to maintain joint line obliquity (JLO), and to evaluate clinical outcomes and level of patient satisfaction at a follow-up of two years.

METHODS

A single-centre, prospective observational study including 22 patients who underwent DLO by PSCGs between 2014 and 2018 was performed. Post-operative alignment was evaluated and compared with the target angular values to define the accuracy of the correction for the hip-knee-ankle angle (ΔHKA), medial proximal tibial angle (ΔMPTA), lateral distal femoral angle (ΔLDFA), and posterior proximal tibial angle (ΔPPTA). Pre- and post-operative JLO was also evaluated. At two year follow-up, changes in the KOOS sub-scores and patient satisfaction were recorded. The Mann-Whitney U test with 95% confidence interval (95% CI) was used to evaluate the differences between two variables; the paired Student's t test was used to estimate evolution of functional outcomes.

RESULTS

The mean ΔHKA was 1.3 ± 0.5°; the mean ΔMPTA was 0.98 ± 0.3°; the mean ΔLDFA was 0.94 ± 0.2°; ΔPPTA was 0.45 ± 0.4°. The orientation of the joint line was preserved with a mean difference in the JLO of 0.4 ± 0.2. At last follow-up, it was recorded a significant improvement in all KOOS scores, and 19 patients were enthusiastic, two satisfied, and one moderately satisfied.

CONCLUSION

Performing a DLO using PSCGs produces an accurate correction, without modification of the joint line orientation and with good functional outcomes at two year follow-up.

[Clinical application of split three-dimensional printing patient-specific instrumentation in medial open-wedge high tibial osteotomy]

Objective

To investigate the accuracy of split three-dimensional (3D) printing patient-specific instrumentation (PSI) in medial open-wedge high tibial osteotomy (MOWHTO) and its effectiveness in treating medial knee osteoarthritis.

Methods

Clinical data of 14 patients with medial knee osteoarthritis and treated with split 3D printing PSI-assisted MOWHTO between August 2019 and August 2020 were retrospectively analyzed. There were 5 males and 9 females with an average age of 61 years (range, 43-68 years). The disease duration ranged from 1 to 16 years, with an average of 4.7 years. Preoperative Kellgren-Lawrence grading of knee osteoarthritis included grade Ⅰ in 2 cases, grade Ⅱ in 6 cases, and grade Ⅲ in 6 cases. The Hospital for Special Surgery (HSS) score was 59.1±4.9. The weight bearing line ratio (WBL), hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), posterior tibial slope angle (PTSA), and actual correction angle of the lower limbs were measured on postoperative imaging data, and compared with the preoperative measurements and the designed target values to evaluate the accuracy of the PSI-assisted surgery. The patients' knee function were evaluated with the HSS score at 3 and 6 months postoperatively, and at last follow-up.

Results

One patient suffered from an incision exudation at 2 weeks postoperatively, and the incision healed after symptomatic treatment. The incisions of other patients healed by first intention. All patients were followed up 7-19 months (mean, 14.8 months). There was no neural injuries, hinge fracture, plate or screw fractures, loosening, or other complications. The WBL was maintained at the postoperative level according to the X-ray examination during the follow-up period. The WBL, HKA, MPTA, and PTSA were all within a satisfactory range after operation. The WBL, HKA, and MPTA were significantly improved when compared with the preoperative measurements ( P<0.05). There was no significant difference between preoperative and postoperative PTSA ( P>0.05). The differences in postoperative WBL, HKA, MPTA, and correction angle compared with the preoperative designed target values were not significant ( P>0.05). The HSS scores were 69.2±4.7, 77.7±4.3, and 88.1±5.4 at 3 and 6 months postoperatively, and last follow-up, respectively. The differences between time points were significant ( P<0.05).

Conclusion

For patients with medial knee osteoarthritis, the split 3D printing PSI can assist the surgeon in MOWHTO with accurate osteotomy orthopedics and achieve favorable effectiveness.

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.

CT based PSI blocks for osteotomies around the knee provide accurate results when intraoperative imaging is used

Purpose

Correction osteotomies around the knee are common methods for the treatment of varus or valgus malalignment of the lower extremity. In recent years, patient specific instrumentation (PSI) guides were introduced in order to enhance the accuracy of these procedures. The purpose of this study was to determine the accuracy of CT based PSI guides for correction osteotomies around the knee of low volume osteotomy surgeons and to evaluate if CT based PSI blocks deliver a high degree of accuracy without using intraoperative fluoroscopy.

Methods

Two study arms with CT based PSI cutting blocks for osteotomies around the knee were conducted. Part one: A retrospective analysis of 19 osteotomies was made in order to evaluate the accuracy in the hands of a low volume surgeon on long-leg radiographs. Part two: A cadaveric study with 8 knees was performed for the purpose of analyzing the accuracy without using intraoperative fluoroscopy on pre- and postoperative CT scans. Hip-Knee-Ankle angle (HKA), lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were analyzed. The mean absolute delta (∂) between the planned and postoperative parameters were calculated. The accuracy of both study arms were compared.

Results

Part one: The mean MPTA ∂, LDFA ∂ and HKA ∂ was 0.9°, 1.9° and 1.5°, respectively. Part two: The mean MPTA ∂ and LDFA ∂ was 3.5° and 2.2°, respectively. The mean ∂ of MPTA is significantly different between clinical patients with fluoroscopic control and cadaveric specimens without fluoroscopic control (P < 0.001). All surgeries were performed without complications such as a hinge fracture.

Conclusion

The clinical use of PSI guides for osteotomies around the knee in the hands of low volume surgeons is a safe procedure. The PSI guides deliver a reliable accuracy under fluoroscopic control whereas their non-use of intraoperative fluoroscopy leads to a lack of accuracy. The use of fluoroscopic control during PSI guided correction osteotomies is highly recommended.

Level of evidence

IV – Retrospective and experimental Study

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.

In-House, Fast FDM Prototyping of a Custom Cutting Guide for a Lower-Risk Pediatric Femoral Osteotomy

Three-dimensional printed custom cutting guides (CCGs) are becoming more and more investigated in medical literature, as a patient-specific approach is often desired and very much needed in today’s surgical practice. Three-dimensional printing applications and computer-aided surgical simulations (CASS) allow for meticulous preoperatory planning and substantial reductions of operating time and risk of human error. However, several limitations seem to slow the large-scale adoption of 3D printed CCGs. CAD designing and 3D printing skills are inevitably needed to develop workflow and address the study; therefore, hospitals are pushed to include third-party collaboration, from highly specialized medical centers to industrial engineering companies, thus increasing the time and cost of labor. The aim of this study was to move towards the feasibility of an in-house, low-cost CCG 3D printing methodology for pediatric orthopedic (PO) surgery. The prototype of a femoral cutting guide was developed for its application at the IOR—Rizzoli Orthopedic Institute of Bologna. The element was printed with an entry-level 3D printer with a high-temperature PLA fiber, whose thermomechanical properties can withstand common steam heat sterilization without bending or losing the original geometry. This methodology allowed for extensive preoperatory planning that would likewise reduce the overall surgery time, whilst reducing the risks related to the intervention.

Evaluation of the "Minimal Clinically Important Difference" (MCID) of the KOOS, KSS and SF-12 scores after open-wedge high tibial osteotomy

PURPOSE

Defining a Minimal Clinically Important Difference (MCID) value for Patient-Reported Outcome Measures (PROMs) is crucial for determining the effectiveness of a procedure and calculating the sample size for trial planning. The purpose of this study was to determine the MCID of several PROMs (Knee injury and Osteoarthritis Outcome Score (KOOS), Knee Society Score (KSS) and the SF-12) in patients who underwent medial opening-wedge High-Tibial Osteotomy (owHTO) with Patient-Specific Cutting Guides (PSCGs), using anchor-based methods.

METHODS

Patients undergoing isolated medial owHTO with PSCGs between January 2013 and January 2017 were enrolled in this single-center, prospective, observational study. Three outcome scores were collected pre-operatively and at the 2 years follow-up evaluation: KOOS, KSS and SF-12. The MCIDs were calculated using anchor-based method: at 2 years postoperatively: "Compared with before surgery, how would you rate operated joint now?" The responses were recorded using a five-point scale. Patients who answered "about the same" or "somewhat worse" were classified into the no change group, while those who answered "somewhat better" were classified into the minimal change group. A receiver operating characteristic (ROC) curve was used to define the cutoff point that best discriminated between the minimal change and no change groups for each PROMs RESULTS: 196 patients were included, 75 (somewhat better) and 24 patients (about the same and somewhat worse) were, respectively, assigned to the "no change" and "minimal change" groups. There was no significant difference between the two groups in terms of baseline characteristics and postoperative complications. At 24 months follow-up all the PROMs (KOOS, KSS and SF-12) were significantly better for the "minimal change" group compared to the "no change" group. MCID was 15.4 for KOOS pain, 15.1 for KOOS symptoms, 17 for KOOS ADL, 11.2 for KOOS sports/recreation, 16.5 for KOOS QQL, 3 for KSS symptoms, 5.6 for KSS activity, 7.2 for SF-12 physical component and 6.3 for PCS mental component.

CONCLUSION

This study determined the MCIDs of common used PROMs in patients undergoing owHTO.

LEVEL OF EVIDENCE

Prospective Cohort Study, Level II.

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

INTRODUCTION

Preoperative planning in high tibial osteotomy (HTO) is a critical step for achieving the desired correction and a clinically satisfactory outcome. Conventional radiography, navigation assistance and patient-specific instrumentation (PSI) are the 3 means of planning, but no prospective studies have compared precision between the 3. The aims of the present study were: (1) to analyze and compare correction precision between the 3 planning approaches at 1 year's follow-up; (2) to compare results to those reported in the literature; and (3) to analyze factors influencing the achievement of planned correction.

HYPOTHESIS

The study hypothesis was that PSI provides more precise and reproducible planned correction than conventional methods or navigation.

MATERIAL AND METHOD

Between June 2017 and June 2018, a multicenter non-randomized prospective observational study was conducted in 11 centers. One hundred and twenty-six patients with Ahlbäck grade I, II or III idiopathic medial tibiofemoral osteoarthritis with stable knee were included and allocated to 3 preoperative planning groups: conventional (group 1), navigation (group 2) and PSI (group 3). Mean age at surgery was 51.2 years (range, 19-69 years; median, 53.2 years); 100 male, 26 female. Complete weight-bearing radiographic work-up was performed preoperatively and at 1 year's follow-up. The PSI group also underwent CT as part of guide production. Target angular correction and mechanical Hip-Knee-Ankle (HKA) axis were set preoperatively. The main endpoint was the difference between planned HKA and HKA at a minimum 12 months.

RESULTS

Mean HKA difference was 1.1±3 in group 1, 2.1±2.6 in group 2 and 0.3±3.1 in group 3. Precision was better with PSI, but not significantly when comparing all 3 groups together. On pairwise intergroup comparison, there was a significant difference only between groups 2 and 3, in favor of PSI (P=0.011).

DISCUSSION

None of the 3 techniques demonstrated superiority in achieving target correction at 1 year. The study hypothesis was thus not confirmed. All 3 techniques proved reliable and precise in HTO planning.

LEVEL OF EVIDENCE

III, prospective non-randomized comparative study.

A protective hinge wire, intersecting the osteotomy plane, can reduce the occurrence of perioperative hinge fractures in medial opening wedge osteotomy

PURPOSE

A recent study reported that positioning a K-wire to intersect the cutting plane at the theoretical lateral hinge location increases the lateral hinge's resistance to fracture during the opening of opening wedge high tibial osteotomy (OWHTO). The purpose of this study was to evaluate the clinical relevance of the use of this K-wire and its benefits in terms of lateral hinge protection during OWHTO in daily practice.

METHODS

A retrospective comparative study identified 206 patients who underwent OWHTO from January 2014 to December 2017. Among these patients, 71 had an additional K-wire (HK + group), whereas 135 did not (HK- group). The subjects meeting the inclusion criteria were included in a matched pairing process, which identified 60 patients in the HK + group and 60 patients in the HK- group. Mean follow-up time was 2.3 ± 1.0 years (range 2-4.2). Radiographic outcomes were evaluated with intraoperative and postoperative fluoroscopic imaging and with CT imaging at 6 weeks post OWHTO surgery. The knee osteoarthritis outcomes score (KOOS) was used and time needed to return to work and any kind of sports was collected.

RESULTS

Thirty six patients (30%) were found to have a LHF. Among these patients, 26 (72%) did not have an additional K-wire positioned at their theoretical lateral hinge location (HK- group) during the procedure. LHF rate for patients without additional K-wire group (HK-) was 43.3%, whereas it was 16.7% for the patients with an additional K-wire (HK +) [Odd ratio 3.8 95% CI 1.6-8.3; p = 0.005]. The mean time to return to work, return to any kind of sports, and bone union was significantly shorter for HK + group (p < 0.05).

CONCLUSION

This study demonstrated that during OWHTO, positioning a K-wire intersecting the cutting plane at the theoretical lateral hinge location reduced the number of intraoperative lateral hinge fractures.

LEVEL OF EVIDENCE

III retrospective case-control study.

Coronal Alignment Correction and Maintenance of Tibial Slope in Opening-Wedge Valgus High Tibial Osteotomy Using a 4-Reference Kirschner Wire Technique: A Cadaveric Study

Background

Opening-wedge valgus high tibial osteotomy (OWHTO) is a common surgical procedure used to treat symptomatic varus femorotibial malalignment in adults. Several intraoperative methods are available to determine the correct correction alignment, but achieving the desired alignment correction is difficult.

Purpose/Hypothesis

The aim of this study was to assess a 4-reference K-wire technique that is relatively easy to apply and can reliably assess actual alignment correction during surgery after determination of the desired corrective angle. We hypothesized that this technique would accurately determine the coronal correction and properly maintain the tibial slope intraoperatively during OWHTO.

Study Design

Descriptive laboratory study.

Methods

This study was conducted using 12 fresh-frozen cadavers; 12 randomly chosen knees were corrected 5° and 12 knees were corrected 10° by use of 2 coronal and 2 sagittal K-wires. The first and second coronal K-wires were drilled at 4 cm and 1 to 2 cm below the medial joint line toward the tibiofibular joint, respectively. The angles of these 2 coronal K-wires were measured before and after the gap was opened via a modified goniometer. The difference in the angle formed by these 2 coronal K-wires from before to after opening of the gap was the alignment correction angle. In addition, 2 sagittal K-wires were drilled parallel to each other before the gap opening above and below the osteotomy site. Ensuring that these 2 sagittal K-wires remained parallel after the gap opening confirmed that the tibial slope had been maintained. The paired t test was used to compare the desired alignment corrections and the different angles measured between the pre- and postoperative radiographic alignments.

Results

The mean ± SD differences in angles between the pre- and postoperative alignments of the 5° and 10° corrections were 5.04° ± 0.68° and 10.03° ± 0.68°, respectively, indicating no statistically significant differences between pre- and postoperative alignment in both groups. As well, no significant difference was noted between the pre- and postoperative medial tibial slope (P = .54).

Conclusion

The coronal alignment correction and maintenance of the tibial slope using the 4-reference K-wire technique was found to be highly accurate and reliable.

Clinical Relevance

Achieving the correct angle in OWHTO is difficult, and the 4-reference K-wire technique provides an easier and more reliable way to obtain the correct angle. This technique can be used in most hospital settings, with no need for expensive equipment.

Accuracy of 3D-planned patient specific instrumentation in high tibial open wedge valgisation osteotomy

Purpose

High tibial osteotomy (HTO) is an effective treatment option in early osteoarthritis. However, preoperative planning and surgical execution can be challenging. Computer assisted three-dimensional (3D) planning and patient-specific instruments (PSI) might be helpful tools in achieving successful outcomes. Goal of this study was to assess the accuracy of HTO using PSI.

Methods

All medial open wedge PSI-HTO between 2014 and 2016 were reviewed. Using pre- and postoperative radiographs, hip-knee-ankle angle (HKA) and posterior tibial slope (PTS) were determined two-dimensionally (2D) to calculate 2D accuracy. Using postoperative CT-data, 3D surface models of the tibias were reconstructed and superimposed with the planning to calculate 3D accuracy.

Results

Twenty-three patients could be included. A mean correction of HKA of 9.7° ± 2.6° was planned. Postoperative assessment of HKA correction showed a mean correction of 8.9° ± 3.2°, resulting in a 2D accuracy for HKA correction of 0.8° ± 1.5°. The postoperative PTS changed by 1.7° ± 2.2°. 3D accuracy showed average 3D rotational differences of − 0.1° ± 2.3° in coronal plane, − 0.2° ± 2.3° in transversal plane, and 1.3° ± 2.1° in sagittal plane, whereby 3D translational differences were calculated as 0.1 mm ± 1.3 mm in coronal plane, − 0.1 ± 0.6 mm in transversal plane, and − 0.1 ± 0.6 mm in sagittal plane.

Conclusion

The use of PSI in HTO results in accurate correction of mechanical leg axis. In contrast to the known problem of unintended PTS changes in conventional HTO, just slight changes of PTS could be observed using PSI. The use of PSI in HTO might be preferable to obtain desired correction of HKA and to maintain PTS.