Coronal tibiofemoral subluxation is correlated to correction angle in medial opening wedge high tibial osteotomy

Increase in the Posterior Tibial Slope Provides Better Joint Awareness and Patient Satisfaction in Cruciate-Retaining Total Knee Arthroplasty

The effect of the posterior tibial slope (PTS) in cruciate-retaining total knee arthroplasty (CR-TKA) on clinical outcomes remains unclear. We aimed to investigate (1) the effect of alteration of the PTS on clinical outcomes, including patient satisfaction and joint awareness, and (2) the relationship between the patient-reported outcomes, the PTS, and compartment loading. Based on the alteration of the PTS after CR-TKA, 39 and 16 patients were stratified into increased and decreased PTS groups, respectively. Clinical evaluation was performed by the Knee Society Score (KSS) 2011 and the Forgotten Joint Score-12 (FJS-12). Compartment loading was intraoperatively assessed. KSS 2011 (symptoms, satisfaction, and total score) was significantly higher (p = 0.018, 0.023, and 0.040, respectively), and FJS ("climbing stairs?") was significantly lower (p = 0.025) in the increased PTS group compared with the decreased PTS group. The decrease in both medial and lateral compartment loading of Δ45°, Δ90°, and ΔFull was significantly greater in the increased PTS group than in the decreased PTS group (p< 0.01 for both comparisons). Medial compartment loading of Δ45°, Δ90°, and ΔFull significantly correlated with KSS 2011 for "symptom" (r = - 0.4042, -0.4164, and -0.4010, respectively; p = 0.0267, 0.0246, and 0.0311, respectively). ΔPTS significantly correlated with medial compartment loading differentials of Δ45°, Δ90°, and ΔFull (r = - 0.3288, -0.3792, and -0.4424, respectively; p = 0.0358, 0.01558, and 0.0043, respectively). Patients with increased PTS showed better symptoms and higher patient satisfaction compared with those with decreased PTS following CR-TKA, possibly due to a greater decrease in compartment loading during knee flexion.Level of evidence:level IV, therapeutic case series.

Restricted kinematically aligned total knee arthroplasty with an anatomically designed implant can restore constitutional coronal lower limb alignment

PURPOSE

Restricted kinematically aligned total knee arthroplasty (rKA-TKA) may not restore the constitutional varus alignment in most patients with knee osteoarthritis. This study aimed to investigate (1) the extent to which constitutional lower limb alignment can be restored by rKA-TKA using an anatomically designed implant and (2) which lower limb alignment parameters are associated with patient-reported outcome measures (PROMs).

METHODS

This study included 60 patients who underwent rKA-TKA using an anatomically designed implant. Radiographic alignment parameters, including mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), coronal hip-knee-ankle angle (HKA), coronal joint line obliquity (JLO), posterior tibial slope (PTS), single-leg standing knee flexion angle (KFA), sagittal JLO, and arithmetic HKA (aHKA), were evaluated preoperatively and postoperatively. The Western Ontario and McMaster Universities Arthritis Index (WOMAC) was used for clinical evaluation.

RESULTS

The mLDFA, MPTA, and aHKA showed no significant differences before and after surgery. Coronal HKA and PTS have significantly changed from 8.1 ± 8.7° and 9.9 ± 8.6° preoperatively to 3.5 ± 3.1° and 2.5 ± 2.0° postoperatively, respectively (p < 0.001 for each comparison). The postoperative WOMAC total score was significantly correlated with the KFA (r = 0.4063, p = 0.0034) and sagittal JLO (r = -0.3435, p = 0.0157). Postoperative KFA is a causal factor for the increased postoperative WOMAC total score (r = 1.416, 95% confidence interval: 0.491-2.342, p = 0.003).

CONCLUSION

rKA-TKA using an anatomically designed implant can restore constitutional coronal lower limb alignment, while postoperative KFA and sagittal JLO were associated with poor PROMs. Care should be taken for the postoperative KFA because it is a risk factor for poor PROMs.

LEVEL OF EVIDENCE

Level III, case-control study.

Clinical relevance of joint line obliquity after high tibial osteotomy for medial knee osteoarthritis remains controversial: a systematic review

PURPOSE

To systematically review the literature on the association between knee joint line obliquity (KJLO) and clinical outcome after high tibial osteotomy (HTO) for medial knee osteoarthritis and summarize the KJLO cut-off value used when studying this association.

METHODS

A systematic search was conducted in three databases (PubMed, Embase, and Web of Science) on September 2022, updated on February 2023. Eligible studies describing postoperative KJLO in relation to clinical outcome after HTO for medial knee osteoarthritis were included. Nonpatient studies and conference abstracts without full-text were excluded. Two independent reviewers assessed title, abstract and full-text based on the inclusion and exclusion criteria. The modified Downs and Black checklist was used to assess the methodological quality of each included study.

RESULTS

Of the seventeen studies included, three had good methodological quality, thirteen fair quality, and one had poor quality. Conflicting findings were shown on the associations between postoperative KJLO and patient-reported outcome, medial knee cartilage regeneration, and 10-year surgical survival in sixteen studies. Three good-quality studies found no significant differences in lateral knee cartilage degeneration between postoperative medial proximal tibial angle > 95° and < 95°. Joint line orientation angles by the tibial plateau of 4° and 6°, joint line orientation angle by the middle knee joint space of 5°, medial proximal tibial angles of 95° and 98°, and Mikulicz joint line angle of 94° were KJLO cut-off values used in the included studies.

CONCLUSION

Based on current evidence, the actual association between postoperative KJLO and clinical consequences after HTO for medial knee osteoarthritis cannot be ascertained. The clinical relevance of KJLO after HTO remains controversial.

LEVEL OF EVIDENCE

IV.

Incidence and risk factors for lateral hinge fractures in medial opening wedge high tibial osteotomy and medial opening wedge distal tibial tuberosity osteotomy

BACKGROUND

The aims of this study were (1) to compare the incidence of lateral hinge fractures (LHFs) in medial opening-wedge high tibial osteotomy (OWHTO) and medial opening-wedge distal tibial tuberosity osteotomy (DTO), and (2) to investigate the risk factors for LHFs. The incidence of LHFs was hypothesized to be higher in the DTO group than the OWHTO group. The DTO procedure is also a risk factor for LHFs.

METHODS

A total of 167 knees that underwent OWHTO (n = 65) and DTO (n = 102) were subjected to propensity score matching for the comparison of the groups. The matched variables were sex, preoperative hip-knee-ankle (HKA) angle, and preoperative medial proximal tibial angle. Forty-one matched pairs were enrolled for comparative analysis. Logistic regression analysis was performed to investigate risk factors for LHFs.

RESULTS

The incidence of LHFs was not significantly different between the groups (34.1% vs. 26.8%, respectively; p = 0.631). Logistic regression analysis showed that age (odds ratio: 1.074, 95% confidence interval (CI): 1.020-1.131, p = 0.007), BMI (odds ratio: 1.150, 95% CI: 1.049-1.260, p = 0.003), and preoperative HKA angle (odds ratio: 1.150, 95% CI: 1.049-1.260, p = 0.035) were significant risk factors for LHFs. The difference in surgical technique between OWHTO and DTO was not a risk factor for LHFs (p = 0.204).

CONCLUSIONS

The incidence of LHFs is similar in DTOs and OWHTOs, and the DTO procedure is not a risk factor for LHFs.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Coronal tibiofemoral subluxation under valgus stress force radiography is useful for evaluating postoperative coronal tibiofemoral subluxation in mobile-bearing UKA

PURPOSE

Coronal tibiofemoral subluxation (CTFS) is considered a controversial and potential contraindication to unicompartmental knee arthroplasty (UKA) but is less discussed. The study aims to observe the CTFS in a cohort of patients before and after mobile-bearing UKA and to investigate the relationship between preoperative variables (preoperative CTFS and preoperative CTFS under valgus stress) and postoperative CTFS after mobile-bearing UKA.

METHODS

The study retrospectively analyzed 181 patients (224 knees) undergoing mobile-bearing UKA from September 1 2019 to December 31 2021. By using hip-to-ankle anterior-posterior (AP) standing radiographs and valgus stress force radiographs, preoperative CTFS, preoperative CTFS under valgus stress, and postoperative CTFS were measured. CTFS was defined as the distance between the tangent line to the outermost joint edge of the lateral condyle of the femur and the tangent line of the lateral tibial plateau. All patients were divided into two groups based on postoperative CTFS, group A (postoperative CTFS ≤ 5 mm) and group B (postoperative CTFS > 5 mm). The Student's t-test, one-way ANOVA together with Tukey's post hoc test, the chi-square test, the Fisher's exact test, Pearson correlation analysis, simple and multiple linear regression, and univariate and multiple logistic regression were used in the analyses.

RESULTS

The means ± standard deviations (SD) of preoperative CTFS, preoperative CTFS under valgus stress, and postoperative CTFS were 4.96 ± 1.82 mm, 3.06 ± 1.37 mm, and 3.19 ± 1.27 mm. The difference between preoperative CTFS and postoperative CTFS was statistically significant (p < 0.001). The preoperative CTFS (6.35 ± 1.34 mm) in Group B (n = 22) was significantly higher than that (4.81 ± 1.82 mm) in Group A (n = 202) (p < 0.001), so was the variable-preoperative CTFS under valgus stress (5.41 ± 1.00 mm (Group B) > 2.80 ± 1.14 mm (Group A), p < 0.001). In Pearson correlation analysis, there was a correlation between preoperative CTFS and postoperative CTFS (r = 0.493, p < 0.001), while the correlation between preoperative CTFS under valgus stress and postoperative CTFS was stronger (r = 0.842, p < 0.001). In multiple linear regression analysis, preoperative CTFS under valgus stress (β = 0.798, 95% confidence interval (CI) = 0.714-0.883, p < 0.001) was significantly correlated with postoperative CTFS. In multiple logistic regression analysis, preoperative CTFS under valgus stress (OR = 12.412, 95% CI = 4.757-32.384, and p < 0.001) was expressed as the risk factor of postoperative CTFS (> 5 mm).

CONCLUSION

Preoperative CTFS can be improved significantly after mobile-bearing UKA. In addition, postoperative CTFS is correlated with preoperative CTFS under valgus stress and a higher preoperative CTFS under valgus stress will increase the risk of higher postoperative CTFS (> 5 mm).

LEVEL OF EVIDENCE

Level III.

Factors Associated With Unfavorable Radiological Outcomes After Opening-Wedge High Tibial Osteotomy for Varus Knees

BACKGROUND

Corrective osteotomy around the knee is based on deformity profiles of the femoral and tibial sides. Opening-wedge high tibial osteotomy (OWHTO) can be favored if the outcomes are not different, even if there is a certain degree of abnormal parameters after correction.

PURPOSE/HYPOTHESIS

The purpose of this study was to identify the factors associated with unfavorable radiological outcomes after OWHTO for varus knees. Our hypothesis was that there would be an optimal situation in which double-level osteotomy (DLO) has advantages over isolated OWHTO and an optimal cutoff value of structural parameters for which DLO should be considered in patients with severe varus knees.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The radiological and clinical outcomes of 337 patients who underwent OWHTO were retrospectively evaluated. A subgroup analysis was performed according to the weightbearing line ratio (WBLR) (group 1: <25th percentile; group 2: 25th-75th percentile; and group 3: >75th percentile) and factors associated with unfavorable radiological outcomes. For the assessment of cutoff values of the parameters favoring DLO, unfavorable radiological outcomes were categorized as follows: (1) medial proximal tibial angle (MPTA) >95°, (2) joint-line convergence angle (JLCA) >4° (insufficient medial release), (3) JLCA <0° (medial instability), (4) recurrence of a varus deformity, and (5) lateral hinge fracture.

RESULTS

The mean follow-up period was 66.2 ± 19.1 months. A low preoperative WBLR was related to a larger preoperative to postoperative change (Δ) in the WBLR, a larger reduction in coronal translation, a larger ΔMPTA, a wide preoperative lateral joint space, and a narrow preoperative medial joint space (P < .001, P < .001, P < .001, P = .016, and P = .003, respectively). However, only an MPTA >95° was significantly related to a low WBLR in the subgroup analysis according to unfavorable radiological outcomes (P = .038). The cutoff value of ΔWBLR causing an MPTA >95° was 46.5%, which showed a good area under the curve of 0.800, with a sensitivity of 74.4% and a specificity of 82.7%. The clinical outcomes significantly improved at the final follow-up compared with those preoperatively, with no significant differences between the WBLR groups.

CONCLUSION

A ΔWBLR ≥46.5% led to an MPTA >95°. However, clinical outcomes were not affected. DLO should be considered if the surgeon desires a postoperative MPTA ≤95°.

Coronal tibiofemoral subluxation in patients with osteoarthritis was corrected after total knee arthroplasty

The objective of this study was to investigate the effect of preoperative coronal tibiofemoral subluxation (CTFS) on postoperative mechanical alignment in patients undergoing total knee arthroplasty (TKA) for primary knee osteoarthritis (OA) and to investigate whether TKA can correct preoperative CTFS. We hypothesized that TKA would correct CTFS in patients with knee OA. A retrospective analysis of 102 patients with knee OA who underwent TKA was performed. The preoperative and postoperative CTFS and mechanical alignment were measured and compared. At the same time, the baseline values of CTFS and mechanical alignment in "normal" patients were measured and compared with those in the operation group. Eighty patients were eventually enrolled in the study. Mechanical alignment was corrected from 7.3 ± 5.2°, preoperatively, to 1.6 ± 2.3° postoperatively, while the tibiofemoral subluxation was corrected from 5.3 ± 2.6 mm, preoperatively, to 2.3 ± 2.7 mm postoperatively. There was no significant correlation between preoperative CTFS and gender (r = 0.03), BMI (r = -0.09), age (r = 0.05), or preoperative mechanical alignment (r = 0.09). In addition, there was no correlation between the degree of correction of CTFS and the degree of correction of overall mechanical alignment (r = 0.14). The difference between the value for CTFS in the "normal" patients and the preoperative value for arthritis cohorts were statistically significant (P = .004). However, no significant difference was appreciated between the value for CTFS in the "normal" patients and the postoperative value for TKA cohorts (P = .25). Preoperative CTFS does not affect postoperative mechanical alignment. Excellent TKA can correct preoperative CTFS in OA patients to reduce prosthesis wear and improve postoperative patient satisfaction.

Medial proximal tibial angle at the posterior tibial plateau represents the pre-arthritic constitutional medial proximal tibial angle in anterior cruciate ligament-intact, advanced osteoarthritis of the knee

PURPOSE

In kinematically aligned total knee arthroplasty (TKA), it is necessary to infer the pre-arthritic constitutional medial proximal tibial angle (MPTA) in advanced osteoarthritis (OA) of the knee with bone loss. The aim of this study was to investigate whether MPTA at the posterior tibial plateau represents the pre-arthritic constitutional MPTA in anterior cruciate ligament (ACL)-intact, advanced OA knees. It was hypothesized that MPTA at the posterior tibial plateau represents the pre-arthritic constitutional MPTA of ACL-intact, advanced knee OA.

METHODS

One hundred varus, anterior cruciate ligament (ACL)-intact, advanced OA knees were analysed. The hip-knee-ankle (HKA) angle and MPTA were assessed on computed radiography (CR) and MPTAs at the anterior, middle, and posterior part of the tibial plateau were assessed on computed tomography (CT) images. The association between these parameters was also analysed.

RESULTS

CR images showed an HKA angle of 172.4 ± 4.1° and MPTA of 84.3 ± 2.5°. CT images showed different MPTAs in the three regions, ranging from 83.9 ± 2.4° to 85.9 ± 2.8°. The middle MPTA was the lowest at 83.9 ± 2.4°. HKA angle correlated with the middle MPTA (r = 0.3355, 95% confidence interval [CI] 0.1489-0.4991, p = 0.0006) and ΔMPTA (Middle-Posterior) (r = 0.5128, 95% CI 0.3518-0.6443, p < 0.0001).

CONCLUSION

The MPTA at the posterior tibial plateau represents the pre-arthritic constitutional MPTA in ACL-intact, advanced OA knees.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Distal tibial tubercle osteotomy can lessen change in patellar height post medial opening wedge high tibial osteotomy? A systematic review and meta-analysis

Objective

Medial opening wedge high tibial osteotomy (MOWHTO) is a mainstream surgical method for treating early medial compartment knee osteoarthritis. Undesirable sequelae such as patella infera may happen following tuberosity osteotomy. We conducted this systematic review and meta-analysis to compare the change in patellar position after proximal tibial tubercle osteotomy (PTO) versus distal tibial tubercle osteotomy (DTO) intervention.

Methods

The 11 studies were acquired from PubMed, Medline, Embase and Cochrane Library. The data were extracted by two of the coauthors independently and were analyzed by RevMan5.3. Mean differences, odds ratios and 95% confidence intervals were calculated. Cochrane Collaboration’s Risk of Bias Tool and Newcastle–Ottawa Scale were used to assess risk of bias.

Results

Eleven observational studies were assessed. The methodological quality of the trials ranged from moderate to high. The pooled results of postoperative patellar height (Caton-Deschamps index and Blackburne-Peel index) and postoperative complications showed that the differences were statistically significant between PTO and DTO interventions. Patellar index ratios decreased significantly in the PTO groups, and 12 (9.2%) complications under DTO surgery and 2 (1.6%) complications under PTO surgery were reported. The differences of postoperative posterior tibial slope (angle) was not statistically significant, but postoperative posterior tibial slope of both groups increased. Sensitivity analysis proved the stability of the pooled results and the publication bias was not apparent.

Conclusions

DTO in MOWHTO maintained the postoperative patellar height, and clinically, for patients with serious patellofemoral osteoarthritis, DTO can be preferred. Postoperative complications are easily preventable with caution. In view of the heterogeneity and small sample size, whether these conclusions are applicable should be further determined in future studies.

Effect of bone morphology of the tibia plateau on joint line convergence angle in medial open wedge high tibial osteotomy

Background

Change in the joint line convergence angle (JLCA) of the knee after high tibial osteotomy (HTO) is difficult to predict accurately. Given that any change in JLCA is intra-articular, the shape of the articular surface, including the bone morphology of the proximal tibia, may affect the alignment of the knee joint postoperatively. The purpose of this study was to investigate the relationship between the shape of the tibial plateau and postoperative alignment of the knee joint by focusing on changes in JLCA.

Methods

One hundred and nine knees that underwent HTO were retrospectively reviewed. The shape of the tibial plateau was classified based on the slope of the medial and lateral articular surfaces as depressed, flat (within 3 degrees), or convex (pagoda-like). The relationship between the shape of the tibial plateau and radiological parameters was investigated.

Results

The shape of the tibial plateau was depressed in 38 knees, flat in 52 knees, and pagoda-like in 19 knees. There was a moderate correlation between the postoperative change in JLCA and the preoperative hip-knee-ankle angle for knees with a pagoda-shaped tibial plateau (r = 0.56) but not for the other two shapes.

Conclusions

These findings suggest that knees with marked varus deformity before HTO are likely to show more change in JLCA postoperatively if the tibial plateau is pagoda-shaped than if it has a depressed or flat shape. The advantage of focusing on the bone morphology of the proximal tibia is that surgeons can easily perform visual assessment using preoperative radiograph.

Excessively Increased Joint-Line Obliquity After Medial Opening-Wedge High Tibial Osteotomy Is Associated With Inferior Radiologic and Clinical Outcomes: What Is Permissible Joint-Line Obliquity

PURPOSE

This study aimed to evaluate the permissible joint-line obliquity (JLO) based on radiologic and clinical outcomes with midterm follow-up after medial open-wedge high tibial osteotomy (MOWHTO).

METHODS

Patients who had undergone MOWHTO from March 2014 to May 2016 were retrospectively evaluated. They were divided into 4 groups based on JLO as represented by postoperative medial proximal tibial angle (MPTA). Radiologic parameters including MPTA, joint-line orientation angle (JLOA), joint-line convergence angle (JLCA), posterior tibial slope, weightbearing line ratio (WBLR), and coronal translation were analyzed. Clinical outcomes were evaluated with American Knee Society Score (AKSS), Western Ontario and McMaster University Index, and short-form 36 health survey (SF-36). The changes between preoperation and final follow-up in JLOA and MPTA were defined as ΔJLOA and ΔMPTA.

RESULTS

A total of 135 knees were finally included (MPTA ≤90.32° as group I; 90.33° to 92.62° as group II; 92.74° to 95.22° as group III; and ≥95.23° as group IV). The last follow-up MPTA, JLOA, and JLCA values were different between the groups (P < .001, P < .001, and P = .015, respectively). WBLR and JLOA positively correlated with MPTA; however, WBLR showed an abrupt increase at MPTA >96.5°, and the JLOA distribution tended to be greater than the regression line at MPTA >96°. Moreover, ΔJLOA was not as large as ΔMPTA. The percentage of patients attaining a minimal clinically important difference was significantly lower in the AKSS-functional score and SF-36 physical component summary in group IV (P = .008 and 0.021, respectively).

CONCLUSION

The JLOA did not change as much as the MPTA, but an MPTA >95.2° abruptly increased the JLOA and valgus overcorrection after MOWHTO. Poor clinical outcomes were more evident in excessive MPTA (>95.2°) than in mildly undercorrected or properly corrected MPTA (<95.2°).

LEVEL OF EVIDENCE

III, retrospective cohort study.

Surgical planning of osteotomies around the knee differs between preoperative standing and supine radiographs in nearly half of cases

Background

To evaluate the difference in surgical planning of osteotomies around the knee between preoperative standing and supine radiographs and to identify risk factors for discrepancies in surgical planning.

Methods

This study included 117 knees of 100 patients who underwent osteotomies around the knee for knee osteoarthritis with genu varum. Surgical planning was performed so that the target point of the postoperative weight-bearing line (WBL) ratio was 62.5% in preoperative standing and supine radiographs. If the opening gap would be > 13 mm in open-wedge high tibial osteotomy (OWHTO), closed-wedge HTO (CWHTO) was planned. If the postoperative mMPTA would be > 95° in isolated HTO, double-level osteotomy (DLO) was planned. In DLO, lateral closed-wedge distal femoral osteotomy was performed so that the postoperative mechanical lateral distal femoral angle (mLDFA) was 85°, and any residual varus deformity was corrected with HTO.

Results

Surgical planning differed between standing and supine radiographs in 43.6% of cases. In all knees for which surgical planning differed between standing and supine radiographs, a more invasive type of osteotomy was suggested by standing radiographs than by supine radiographs. The risk factors for discrepancies in surgical planning were a lower WBL ratio in standing radiographs and a lower joint line convergence angle in supine radiographs.

Conclusions

Surgical planning of DLO, CWHTO and OWHTO, in standing radiographs differed from that in supine radiographs in nearly half of the cases. Surgical planning based on standing radiographs leads to more invasive surgical procedures compared to supine radiographs.

Fracture of the tibial tubercle does not affect clinical outcomes in medial opening wedge high tibial osteotomy with distal tibial tubercle osteotomy

PURPOSE

To investigate whether tibial tubercle fracture affected clinical outcomes and bony union in medial opening wedge high tibial osteotomy with distal tibial tubercle osteotomy (DTO) and to determine the anatomical risk factors for tibial tubercle fracture.

MATERIALS AND METHODS

All patients who underwent DTO were retrospectively reviewed, and 104 successive patients were included. The Knee Society Score and complications including tibial tubercle fracture were recorded. On radiographs and computed tomography scans, the length, thickness, width, height, and bony union of the osteotomized tibial tubercle and the posterior tibial slope were statistically analysed.

RESULTS

Fracture of the tibial tubercle occurred intraoperatively in 11 patients (10.6%) and in the postoperative period in 1 (1.0%). The case of postoperative fracture showed non-union. There was no significant difference in the Knee Society Score between the non-fracture and fracture groups. There were significant differences in the posterior tibial slope and the height of the tibial tubercle between the groups (p < 0.0001 for each comparison). The logistic regression analysis showed that the height of the tibial tubercle was associated with a higher risk of the fracture of the tibial tubercle (p < 0.01; OR, 1.548; 95% CI, 1.149-2.085). However, there were no significant differences in the bony union rate of the tibial tubercle at 6 months after surgery between the groups.

CONCLUSIONS

Tibial tubercle fracture did not affect the clinical outcome and bony union in spite of the relatively high occurrence rate. Anatomical risk factors for the fractures was a lower tibial tubercle position.

LEVEL OF EVIDENCE

Level IV.

Influence of preoperative coronal and sagittal tibiofemoral subluxation in knee osteoarthritis on the outcome of primary total knee arthroplasty

BACKGROUND

The effect of osteoarthritis (OA) with tibiofemoral (TF) subluxation on patients undergoing total knee arthroplasty (TKA) has been less studied, and there have been no studies on sagittal knee subluxation which is a component of a three-dimensional problem. We aim to analyze the influence of preoperative coronal and sagittal knee subluxation with OA on other radiological parameters and the functional outcome in patients undergoing TKA.

METHODS

We retrospectively reviewed the 179-consecutive primary TKA in 151 patients from January 2017 to June 2017. The radiological parameters analyzed were the mechanical tibiofemoral angle (HKA), joint line congruence angle (JLCA) and coronal tibiofemoral (CTF) subluxation in long leg films. In the lateral view, posterior tibial slope, the settlement area of the femur over the tibia and the sagittal tibiofemoral (STF) subluxation were calculated. Preoperative and postoperative knee society and knee society functional scores were documented. Multivariate regression analysis was done to determine the association of preoperative radiological parameters with coronal and sagittal TF subluxation.

RESULTS

The average follow-up was 31 months (2.6 years). 102 knees (57%) had CTF subluxation (< 5 mm) within normal range, and 77 knees (43%) had CTF subluxation. There was a direct correlation between the magnitude of CTF subluxation and poor preoperative functional scores compared with the non-subluxation group (p < 0.05). CTF subluxation was not associated with the magnitude of varus deformity as it is correlated more with mild deformity (odds ratio [OR] 10.07, 95% confidence interval [CI] 3.47-29.25) than with moderate and severe varus deformity. The degree of the joint line convergence angle was positively correlated with the amount of CTF subluxation (p = 0.003). STF subluxation had a significant correlation with the posterior slope (p < 0.001), but not with the magnitude of varus deformity (p = 0.26).

CONCLUSION

Coronal and sagittal tibiofemoral subluxation had a significant association with poor preoperative clinical scores. The degree of CTF subluxation reduces with the increasing magnitude of varus deformity and JLCA. STF subluxation was associated with the posterior tibial slope. Patients who underwent posterior stabilized TKA had excellent clinical outcomes irrespective of preoperative knee subluxation.

Geometrical Planning of the Medial Opening Wedge High Tibial Osteotomy—An Experimental Approach

This article presents an experimental approach to the geometrical planning of the medial opening wedge high tibial osteotomy surgery which, as it is known, is an efficient surgical strategy quite widely used in treating knee osteoarthritis. While most of the published papers focus on analyzing this surgery from a medical point of view, we suggest a postoperative experimental evaluation of the intervention from a biomechanical point of view. The geometrical planning and, more specifically, the determination of the point of intersection between the corrected mechanical axis and the medial-lateral articular line of the knee, is a problem quite often debated in literature. This paper aims to experimentally investigate the behavior of the tibia with an open wedge osteotomy fixed with a locking plate, TomoFix (DE Puy Synthes), taking into account two positions of the mechanical axis of the leg on the width of the tibial plateau, measured from medial to lateral at 50% and 62.5% (Fujisawa point), respectively. The variations of the force relative to the deformation, strains, and displacements resulting from the progressive loading of the tibial plateau are studied. The research results reveal that using the Fujisawa point is better for conducting the correction not only for medical reasons, but also from a mechanical point of view.

Short-term outcomes of Oxford unicompartmental knee arthroplasty with coronal subluxation of the knee: a retrospective case–control study

Background

The goal of this study was to assess short-term outcomes in single compartment osteoarthritis patients associated with the coronal tibiofemoral subluxation (CTFS) of the knee joint after Oxford unicompartmental knee arthroplasty (OUKA), and to establish the potential impact of the degree of CTFS on operative outcomes.

Methods

Data pertaining to 183 patients with medial compartment osteoarthritis that underwent OUKA treatment between February 2016 and June 2019 were retrospectively analyzed. The presence and degree of severity of CTFS were assessed using preoperative weight-bearing anteroposterior X-ray images of the knee. Patients were stratified into three subgroups based upon the observed degree of subluxation: a normal group, a mild subluxation group (CTFS < 0.5 cm), and a severe subluxation group (CTFS ≥ 0.5 cm). Anterior and posterior X-ray examination of the knee was conducted at the time of most recent follow-up for each patient to assess the degree of CTFS correction following OUKA. Clinical function was assessed using Oxford knee score (OKS) and Hospital for Special Surgery score (HSS) values, while pain was rated using visual-analog scale (VAS) scores. The mechanical femoral tibial angle (mFTA), range of motion (ROM), and complication rates in these three groups were additionally compared.

Results

The average follow-up duration for patients in this study was 24.1 months (range: 17–32 months). There were no significant differences in patient age, sex, body mass index (BMI), follow-up duration, mFTA, ROM, OKS, HSS, or VAS scores among these three groups (P > 0.05). After surgery, OKS and HSS scores declined significantly, but no differences in these scores were observed among groups (P > 0.05). Of these patients, 135 (73.8%) were satisfied with the operation, of whom 80 (43.7%) were very satisfied. There were no significant differences in ROM or VAS scores among groups (P > 0.05). The degree of CTFS for patients in the mild and severe subluxation groups was significantly improved following OUKA relative to preoperative values such that the degree of postoperative CTFS did not differ significantly among these groups (P > 0.05). Postoperative mFTA was also significantly improved in these three patient subgroups (P < 0.05). No patients experienced operative complications over the follow-up period.

Conclusions

OUKA can successfully improve clinical symptoms in patients with single compartmental osteoarthritis. Moreover, OUKA can effectively correct CTFS of the knee in these patients, and the degree of preoperative CTFS has no impact on surgical efficacy.

Level of evidence

III.

Does Transection of the Superficial MCL During HTO Result in Progressive Valgus Instability? [Formula: see text]

BACKGROUND

During high tibial osteotomy (HTO), the superficial medial collateral ligament (sMCL) is cut or released at any degree to expose the osteotomy site and achieve the targeted alignment correction according to the surgeon's preference. However, it is still unclear whether transection of sMCL increases valgus laxity.

PURPOSE

We aimed to assess the outcomes and safety of sMCL transection, especially focusing on iatrogenic valgus instability.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Seventy-two patients (89 knees) who underwent medial open wedge HTO (MOWHTO) with transection of the sMCL between October 2013 and September 2018 were retrospectively investigated. Clinical evaluations, including the International Knee Documentation Committee (IKDC) score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Tegner and Lysholm scores, were performed preoperatively and at 2 years postoperatively. The radiographic parameters hip-knee-ankle (HKA) angle, joint line convergence angle on standing radiographs (standing JLCA), and weightbearing line (WBL) ratio were assessed preoperatively and at 3 months, 6 months, 1 year, and 2 years postoperatively. To evaluate valgus laxity, we assessed the valgus JLCA and medial joint opening (MJO) at the aforementioned time points using valgus stress radiographs.

RESULTS

All clinical results at the 2-year follow-up were significantly improved compared with those obtained at the preoperative assessment (P < .001). The postoperative HKA angle significantly differed from the preoperative one, and no significant valgus progression was observed during follow-up (preoperative, 8.5°± 2.7°; 3 months, -3.5°± 2.0°; 6 months, -3.2°± 2.3°; 1 year, -3.1°± 2.3°; 2 years, -2.9°± 2.5°; P < .001) The mean WBL ratio was 62.5% ± 9.0% at 2 years postoperatively. The postoperative valgus JLCA at all follow-up points did not significantly change compared with the preoperative valgus JLCA (preoperative, -0.1°± 2.1°; 3 months, -0.2°± 2.4°; 6 months, -0.1°± 2.5°; 1 year, 0.1°± 2.5°; 2 years, 0.2°± 2.2°) The postoperative MJO at all follow-up points did not significantly change compared with the preoperative MJO (preoperative, 7.1 ± 1.7 mm; 3 months, 7.0 ± 1.7 mm; 6 months, 6.9 ± 1.9 mm; 1 year, 6.7 ± 1.8 mm; 2 years, 6.8 ± 1.8 mm).

CONCLUSION

Transection of the sMCL during MOWHTO does not increase valgus laxity and could yield desirable clinical and radiographic results.

Influence of Intraoperative Medial Collateral Ligament Bony Avulsion Injury on the Outcome of Primary Total Knee Arthroplasty

BACKGROUND

The purpose of this study is (1) to find the clinical and radiological outcome of intraoperative bony avulsion of medial collateral ligament (MCL) treated with screw and washer construct and (2) to predict the preoperative factors which may contribute to the avulsion-type MCL injury during primary total knee arthroplasty (TKA).

METHODS

Intraoperative MCL avulsion injury occurred in 46 (0.8%) of the 4916 consecutive primary TKA from January 2011 to December 2015. After exclusion, the 41 knees were matched 1:2 with controls without MCL injury and compared for the various clinical, radiological, and functional parameters. The clinical parameters analyzed were age, gender, body mass index, preoperative diagnosis like osteoarthritis or rheumatoid arthritis, range of motion, sagittal deformity, and vitamin D levels. The radiological parameters calculated were coronal deformity, proximal tibial varus angle, distal femur valgus angle, joint line congruence angle, posterior tibial slope, "cup and saucer" morphology, presence or absence of knee subluxation, tibia vara, and femoral bowing. The preoperative and postoperative Knee Society Score and Knee Society Functional Score were analyzed. Complications or revisions, if any, were noted during the follow-up. Multivariate logistic regression analysis was used to predict the preoperative risk factors for MCL avulsion injury.

RESULTS

At a mean follow-up of 58.4 ± 19.3 months, there were no radiological or physical examination findings of instability. Compared to the preoperative disability, there was a statistically significant improvement in clinical scores (Knee Society Score and Knee Society Functional Score) in the final follow-up (P < .001) in both cases and the control group. The mean preoperative coronal deformity was 170.6 ± 6.96 in the study group and 167.7 ± 4.3 in the control group (P = .021). The mean preoperative tibial slope was 10.5 ± 4.9 in the study group and 7.91 ± 4.15 in the control group (P = .003). The preoperative knee subluxation was present in 48.8% knees (P < .001) and "cup and saucer" morphology in 68.3 knees (P < .001) in the study group. The adjusted odds of MCL avulsion injury were greater for severe varus deformity (odds ratio [OR] 1.462, 95% confidence interval [CI] 1.15-1.86), knee subluxation (OR 39.78, 95% CI 3.78-418.86), and "cup and saucer" morphology (OR 33.11, 95% CI 5.69-192.66).

CONCLUSION

Intraoperative MCL bony avulsion injury can be managed successfully with screw and washer construct without the need for increased prosthetic constraint in primary TKA. The presence of severe varus deformity, knee subluxation, and "cup and saucer" morphology tend to have an increased chance of MCL avulsion injury.

Current Measurement Strategies of Coronal Tibiofemoral Subluxation: A Systematic Review of Literature

OBJECTIVE. Coronal tibiofemoral (TF) subluxation has generated interest in the last several years due to newfound clinical implications of its presence. However, controversy within the literature concerning how to measure and calculate coronal TF subluxation on radiographic imaging remains. The purpose of this study was to describe how coronal TF subluxation is being measured and calculated in the literature with the goal of describing a reproducible and validated technique for clinical adoption. MATERIALS AND METHODS. A PubMed literature search was performed in March 2020 according to PRISMA guidelines. The terms "tibiofemoral subluxation" and "tibial femoral subluxation" were included in the search. Criteria of interest included radiographic view and evaluation, anatomic landmarks used, and measurement validity. RESULTS. Review of relevant literature resulted in 744 articles, 16 of which met our inclusion criteria. A wide range of measuring techniques, anatomic landmarks, and radiographic views were used with varying validity. Full-limb radiographic views were the most common. Six studies measured the translation of the mechanical axes of the tibia and femur. Eight studies measured the translation of either femoral condyle in reference to the tibial plateau. Coordinate-based software with the iterative closest point algorithm was used in two studies. Whether coronal TF subluxation should be divided by tibial plateau width to account for knee size was controversial. CONCLUSION. A variety of approaches exist for diagnosing and quantifying coronal TF subluxation because of the lack of clear anatomic landmarks within the TF joint that can be used to measure coronal TF subluxation in the horizontal plane. Even when using the same anatomic landmarks, studies varied on how to measure coronal TF subluxation radiographically and whether knee size should be accounted for. Further studies are necessary to standardize (via inter- and intraobserver validation with a control group) an easy, reproducible, and minimally biased approach to measuring coronal TF subluxation on radiographic imaging. We believe our systematic review succinctly provides the necessary information to either develop such a tool or encourage future studies to compare existing techniques to find the most reliable and clinically useful approach for evaluating coronal TF subluxation.

Tibiofemoral subluxation in the coronal plane does not affect WOMAC and KOOS after total knee arthroplasty

PURPOSE

To investigate the effect of preoperative coronal tibiofemoral subluxation (CTFS) on functional outcome, prosthesis type, insert thickness and revision rates in patients who underwent total knee arthroplasty (TKA).

METHODS

A total of 224 knees of 186 patients were included. Patients were divided into two groups as either with (Group 1, 114 knees of 86 patients) or without (Group 2, 124 knees of 100 patients) coronal lateral tibiofemoral subluxation. The mean follow-up period was 71.3 ± 7.3 (range 60-84) months in group 1 and 69.4 ± 6.6 (range 61-79) months in group 2 (n.s.). Coronal tibiofemoral subluxation degree was measured in degrees on standing anteroposterior knee radiographs. Group 1 was divided into three subgroups according to amount of subluxation (< 5 mm, 6-10 mm and > 10 mm). Functional outcome was evaluated using the Western Ontario and McMaster Osteoarthritis Index (WOMAC) score and Knee Injury and Osteoarthritis Outcome Score (KOOS) preoperatively and at the last follow-up visit. Prosthesis type, insert thickness and revision rates were compared between the two groups.

RESULTS

There were no significant differences between the two groups regarding patient demographics, prosthesis type, and revision rates (n.s.). The insert thickness was found significantly higher in group 1 (p < 0.001). The preoperative and postoperative WOMAC and KOOS scores were found no significantly different between the two groups (n.s.). Among subluxation (+) subgroups, there was no significant difference in functional outcome scores and revision rates (n.s.). However, prosthesis type and insert thickness were significantly associated with the amount of subluxation (p = 0.009 and p = 0.001, respectively). There was no significant correlation between the degree of lower extremity deformity and coronal tibiofemoral amount of subluxation (n.s.).

CONCLUSION

Preoperative CTFS does not adversely affect the WOMAC score, KOOS and revision rates after TKA. In the clinical practice, surgeons should be aware of the need for a posterior cruciate stabilizing prosthesis and a thicker insert in the presence of CTFS, especially with subluxation greater than 10 mm and to consider a spared bony resection on the tibia in patients suffering from CTFS.

LEVEL OF EVIDENCE

IV.

The Functional Status of the ACL in Varus OA of the Knee: The Association With Varus Deformity and Coronal Tibiofemoral Subluxation

BACKGROUND

The present article analyzes the association of the functional anterior cruciate ligament (ACL) status and the overall varus deformity and coronal tibiofemoral subluxation (CTFS) in varus OA of the knee.

METHODS

One hundred consecutive knees with varus OA in 84 patients were prospectively included. Knees were divided into two groups, in accordance with the ACL status (functionally sufficient or insufficient). All included patients were potential candidates for unicompartmental knee arthroplasty with predominantly medial compartment OA. Knees with Kellgren/Lawrence ≥ grade 3 in the lateral compartment were excluded leaving 79 knees to be included in this study. Mechanical varus deformity and CTFS were evaluated on AP radiographs and valgus stress radiographs, and compared between the two groups.

RESULTS

Knees with a functionally insufficient ACL had significantly more varus deformity on hip-to-ankle AP standing radiographs (P = .001) and on valgus stress radiographs (P = .017). CTFS on AP standing radiographs was significantly higher (P = .045) in knees with a functionally insufficient ACL. Seventy-three percent (8/11) of the ACL-insufficient knees had a varus deformity of ≥10° and 64% (7/11) of ACL-insufficient knees had CTFS ≥ 6mm. By contrast, only one patient (2%, 1/41) with an insufficient ACL had< 10° varus deformity and a CTFS of < 6mm.

CONCLUSION

Functional ACL insufficiency in osteoarthritic varus knees is associated with greater varus deformity and more advanced CTFS. Seventy-three percent of ACL-insufficient knees had a varus deformity of ≥10° and 64% of ACL-insufficient knees a CTFS of ≥ 6mm. In the work-up for medial unicompartmental knee arthroplasty, functional ACL insufficiency is likely in knees with varus deformity of ≥10° and CTFS of ≥ 6mm.

Clinical course and outcomes of simultaneous-versus staged-bilateral medial opening wedge high tibial osteotomy

Background

Difference in the clinical course and outcomes between simultaneous- and staged-bilateral medial opening wedge high tibial osteotomies (OWHTOs) over time was unknown. The study hypothesis was that patients who underwent simultaneous-bilateral OWHTO (SMBO) have a more rapid improvement in knee function than those who underwent staged-bilateral OWHTO (STBO) due to difference in the change of lower limb alignment between SMBO and STBO.

Methods

The records of 56 knees in 28 patients who underwent either SMBO (n = 28) or STBO (n = 28) were retrospectively analysed. The time course data of weight-bearing line percentage (%WBL), joint line convergence angle (JLCA), and Knee Society Score were compared between the two procedures.

Results

Hospitalisation for SMBO was longer than that for STBO by 1 week. No significant difference was observed in %WBL between the two procedures. The JLCA was significantly lower with SMBO than with the first-stage surgery of STBO (P < 0.05), but it became equivalent in both groups at the last follow-up. The knee scores in both SMBO and the first-stage surgery of STBO significantly improved in approximately 1 year. The function scores in the first-stage surgery of STBO did not significantly improve until the completion of the second-stage surgery whereas those in SMBO significantly improved 1 year after surgery and become stable. The function score 1 year after surgery was significantly higher in SMBO than in the first-stage surgery of STBO (p < 0.001).

Conclusions

Although both SMBO and STBO achieved the desired therapeutic results, SMBO led to earlier functional improvement and decreased JLCA compared with STBO.

Large medial proximal tibial angles cause excessively medial tibiofemoral contact forces and abnormal knee kinematics following open-wedge high tibial osteotomy

BACKGROUND

Recurrent varus deformity and poor outcome sometimes occur following open-wedge high tibial osteotomy, but the mechanism remains unclear. The hypothesis of this study was that an excessively large medial proximal tibial angle with lateral joint surface inclination can worsen postoperative knee biomechanics.

METHODS

A computer-simulated knee model was validated based on a volunteer knee. Osteotomy models with medial proximal tibial angles ranging from 90° to 97° in 1° increments were developed. Varus alignment correction of the distal femur was performed in each model to maintain identical coronal alignment passing through a point 62.5% lateral to the tibial plateau. The peak tibiofemoral contact forces and knee kinematics were compared in each model during walking and squatting.

FINDINGS

All the osteotomy models demonstrated higher peak contact forces on the lateral tibiofemoral joints than on the medial tibiofemoral joints during walking. However, larger medial proximal tibial angles caused excessive increases in medial tibiofemoral contact forces, and the dominant tibiofemoral contact forces shifted to the medial side. Increased medial proximal tibial angles also caused progressive medial collateral ligament tension in knee flexion, but partial medial collateral ligament release effectively reduced medial tibiofemoral contact forces. Models with large medial proximal tibial angles showed nonphysiological roll-forward of the lateral femoral condyle during squatting and no screw-home movement around knee extension.

INTERPRETATION

Excessively large medial proximal tibial angles following open-wedge high tibial osteotomy resulted in increased medial tibiofemoral contact forces and abnormal knee kinematics during knee flexion due to medial joint line elevation and ligament imbalance.

Distal tibial tubercle osteotomy is superior to the proximal one for progression of patellofemoral osteoarthritis in medial opening wedge high tibial osteotomy

PURPOSE

To investigate the effect of proximal tibial tubercle osteotomy (PTO) and distal tibial tubercle osteotomy (DTO) in medial opening wedge high tibial osteotomy on patellofemoral alignment, patellofemoral osteoarthritis and clinical outcomes.

METHODS

PTO (n = 41) and DTO (n = 43) for the same surgical indications were included. Radiographic measurements of the Caton-Deschamps index, patellar tilt and shift, and arthroscopic cartilage evaluation at the patellofemoral joint were performed at osteotomy and plate removal. The Knee Society Score (KSS) was evaluated preoperatively and at the latest follow-up.

RESULTS

The follow-up period was longer in the PTO group (33.7 months; range 23-40 years) than in the DTO group (22.2 months; range 18-29 months) (p < 0.0001), whereas the period from osteotomy to plate removal was not different between the groups. The Caton-Deschamps index of the DTO group was unchanged from 0.9 (range 0.7-1.2) to 0.9 (range 0.6-1.4), whereas that of the PTO group changed from 0.9 (0.7-1.2) to 0.7 (0.5-1.0) (p < 0.0001). There were fewer deteriorated cases of cartilage status in the trochlear groove in the DTO group (20.9%) than in the PTO group (56.1%, p < 0.05). There were more improved cases in the DTO group (23.3%) than in the PTO group (4.9%, p < 0.05). Postoperative KSS was better in the DTO group than in the PTO group (p < 0.05).

CONCLUSION

DTO is associated not only with reduced deterioration but also with increased improvement of cartilage status in the trochlear groove and better KSS as compared with PTO.

LEVEL OF EVIDENCE

IV.

How does geometric change after open-wedge high tibial osteotomy affect anterior cruciate ligament status?

BACKGROUND

Open-wedge high tibial osteotomy (OWHTO) produces three- dimensional (3D) geometric changes. Among them, increased posterior tibial slope (PTS), and altered coronal inclination that induces unintended tibial translation may affect anterior cruciate ligament (ACL) status. The purpose of current study was to evaluate the geometric changes following OWHTO, such as increasing PTS and decreasing tibial subluxation, which may affect the status of ACL.

METHODS

From April 2014 to December 2015, a total of 72 knees in 64 patients that underwent OWHTO, second-look arthroscopy, and magnetic resonance imaging (MRI) assessment, were enrolled. Preoperative and postoperative coronal and sagittal translation, joint line orientation angle, the distance between medial femoral notch marginal line and medial tibial spine, and PTS were evaluated. ACL status was arthroscopically graded from grade 1 (best) to 4 (worst). The MRI signal of the graft in three portions (proximal, middle, and distal) was graded from grade 1 (best) to 4 (worst).

RESULTS

High grade (3: partial, and 4: complete rupture) was noted in 28 cases (38.9%) at the second-look arthroscopy compared with 10 cases (13.9%) at index arthroscopy. The MRI signal grade significantly increased at follow up MRI compared with preoperative MRI (P<0.01). An increased signal was commonly noted in the middle and distal portions of the graft.

CONCLUSIONS

Geometric changes after OWHTO were related to ACL deterioration. The ACL was commonly affected at the middle and distal portions and rarely at the proximal portion. There is a possibility of impingement because of the geometric changes.

LEVEL OF EVIDENCE

Level IV.

Tibial condylar valgus osteotomy - indications and technique

PURPOSE

To describe the indications for, and surgical technique of, tibial condylar valgus osteotomy (TCVO).

INDICATIONS

TCVO is commonly performed in patients with middle-to-end-stage medial unicompartmental osteoarthritis. Among the most important TCVO indication criteria are the types of tibial plateau shape. The convex-type (also called "pagoda-type"), with over a 5° joint line convergence angle on the standing X-ray, meets the indication criteria for TCVO.

SURGICAL TECHNIQUE

An L-shaped osteotomy is performed from the medial side of the proximal tibia to the lateral beak of the intercondylar eminence. The apex of the L-shaped osteotomy line is on the medial border of the patellar tendon insertion. Surgeons should note the direction of the chisel (during the osteotomy) to the intercondylar eminence following fluoroscopic guidance. The posterior cortical bone is cut under a lateral view observation, and the crossed-leg position is adopted to prevent injury to the popliteal blood vessels. The spreader should be positioned at the posterior cortical bone to avoid increasing the tibial slope. The locking plate reliably stabilizes the osteotomy and helps shorten the period of postoperative rehabilitation.

CONCLUSIONS

TCVO adjusts varus deformity alongside joint congruity. Accurate identification of indications and a detailed surgical plan would ensure effective correction and proper alignment. Additional osteotomies are recommended in case of under-correction of the varus limb deformity. TCVO is an effective intervention in patients with advanced knee osteoarthritis and lateral joint laxity with the pagoda-type tibial plateau shape.

Effect of increased posterior tibial slope on the anterior cruciate ligament status in medial open wedge high tibial osteotomy in an uninjured ACL population

PURPOSE

The purpose of this study was to clarify the relationship between posterior tibial slope angle (PTSA) and anterior cruciate ligament (ACL) status in medial open wedge high tibial osteotomy (OWHTO). Our hypothesis was that even though OWHTO may improve anteroposterior laxity of the knee, an increase in PTSA after OWHTO would be associated with ACL degeneration.

METHODS

Seventy-five patients treated with OWHTO were retrospectively analyzed. PTSA were evaluated radiographically pre- and postoperatively. The ACL was evaluated during the index arthroscopy at the time of OWHTO and a second-look arthroscopy during the plate removal, and scored from 1 (normal ACL) to 4 (complete tear). An anterior tibial translation (ATT) test was performed.

RESULTS

The mean time period from the index to second-look arthroscopy was 15.0±4.4months. PTSA significantly increased from 5.3±3.4° preoperatively to 7.5±4.0° postoperatively (p<0.001). The average ACL score significantly increased from 1.9±0.5 at the index arthroscopy to 2.2±0.5 at the second-look arthroscopy (p=0.0025). The average ATT on the operated side significantly decreased from 7.1±2.6mm preoperatively to 5.3±2.3mm at the second-look arthroscopy (p<0.0001). There was a significant positive correlation between the increase in PTSA and the change of ACL grade [correlation coefficient (r)=0.221, p<0.05].

CONCLUSION

Even though OWHTO reduces anteroposterior knee laxity, an increase in PTSA is associated with ACL degeneration. It is important for the surgeon to avoid an increase in PTSA during the intervention to prevent ACL degeneration after OWHTO.

LEVEL OF EVIDENCE

IV, therapeutic retrospective case series.

ACL degeneration after an excessive increase in the medial proximal tibial angle with medial open wedge high tibial osteotomy

PURPOSE

This study examined the influence of the mechanical medial proximal tibial angle (MPTA) on anterior cruciate ligament (ACL) degeneration following open wedge high tibial osteotomy (OWHTO). It was hypothesised that an excessive increase in MPTA would be associated with ACL degeneration following OWHTO.

METHODS

Seventy-four knees treated with OWHTO were retrospectively examined. Arthroscopic ACL grading [0 (intact) to 4 (complete rupture)], anterior tibial translation (ATT) test at the time of OWHTO with the index arthroscopy and at plate removal with the second-look arthroscopy, clinical assessments using the Knee Society Score (KSS), and radiographic evaluations of MPTA were performed. The relationship between MPTA and the ACL condition was analysed using Spearman's correlation.

RESULTS

The time from the index arthroscopy to the second-look arthroscopy was 15.0 ± 4.4 months; the total follow-up was 31.0 ± 6.5 months. ACL grade significantly increased from 0.6 ± 0.8 (index arthroscopy) to 1.1 ± 1.2 (second-look arthroscopy) (p < 0.0018). ATT on the operated side significantly decreased from 7.1 ± 2.6 mm preoperatively to 5.3 ± 2.3 mm at the time of plate removal (p < 0.001). No significant difference was observed in KSS for ACL grades in the steady and progression groups. Changes in MPTA from the preoperative to postoperative period were significantly higher in the progression group (p = 0.0155). Changes in ACL grades were significantly correlated with preoperative MPTA and changes in MPTA (r = - 0.365 and 0.343, respectively; p < 0.01).

CONCLUSIONS

Excessively increased MPTA led to ACL degeneration following OWHTO. ACL degeneration was not associated with short-term clinical outcomes. Excessive correction of MPTA should be avoided to prevent ACL degeneration following OWHTO.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.