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

Lateral knee laxity increases the risk of excessive joint line obliquity after medial opening-wedge high tibial osteotomy

BACKGROUND

Medial opening-wedge high tibial osteotomy (HTO) is a well-recognized treatment for patient with varus knee osteoarthritis. Joint line obliquity has recently been suggested to negatively impact clinical outcomes following HTO, but little is known about what factors lead to increased joint line obliquity. The purpose of the current study was (1) to evaluate whether increased preoperative lateral knee laxity, represented by the joint line convergence angle, results in increased joint line obliquity in a consecutive series of patients treated with HTO and (2) to determine the effect of advanced arthritic changes on joint line obliquity.

HYPOTHESIS

Increased joint line convergence angle would be associated with increased joint line obliquity.

PATIENTS AND METHODS

All HTOs performed at our center between 2010-2017 were retrospectively reviewed. Patients were excluded if pre- and postoperative standing alignment radiographs were not available. Varus-producing osteotomies were excluded. Patients were subdivided according to their preoperative joint line convergence angle (≤3° or >3°) and the degree of radiographic arthritic change. The primary outcome measure was the postoperative joint line obliquity. Categorical variables were compared using the paired samples t-test. Survival analysis was performed for failure and overall rate of reoperation.

RESULTS

During the study period, 90 HTO were performed, and 38 patients (42 knees; M/F: 32/6; mean age: 41.6; mean follow-up: 4.72 years) met the inclusion criteria. The most common surgical indications were varus knee osteoarthritis (n=27, 64.3%) and osteochondritis dissecans (n=7, 8.2%). Patients with a preoperative joint line convergence angle >3° demonstrated significantly greater joint line obliquity postoperatively as compared to those with a joint line convergence angle ≤3° (6.4°±4.6° vs. 2.5°±5.7°, respectively; p=0.02). Patients with advanced arthritic changes had significantly lower preoperative (-3°±3.4° vs. -5.6°±4.1°; p=0.03) and greater postoperative (5.8°±4° vs. 2.2°±6.4°; p=0.04) joint line obliquity as compared to those with minimal arthritic changes. There were 12 complications among the 42 procedures: one conversion to total knee replacement (TKR), one hardware failure (fixation revised), one infection, and 9 hardware removals. Overall survival using conversion to TKR was 96.23% (95% CI 0.92-1.0) at 10 years.

DISCUSSION

Lateral knee laxity, as defined by a preoperative joint line convergence angle >3°, and advanced arthritic changes are associated with increased postoperative joint line obliquity following medial opening-wedge high tibial osteotomy. Soft-tissue adaptation should be accounted for in order to avoid excessive joint line obliquity following high tibial osteotomy, and the planned correction should be reduced by 25% in patients with a preoperative joint line convergence angle >3° when templating using standing alignment radiographs.

LEVEL OF EVIDENCE

IV.

Normo-or slightly overcorrection show better results after medial closing wedge high tibial osteotomy

PURPOSE

The objectives of this study were to evaluate functional results, revision-free survival, and the influence of postoperative alignment on outcomes after MCWHTO.

METHODS

This retrospective study included 27 MCWHTO operated on from 2009 to 2021. Radiographic measurements were performed pre- and postoperatively. The HKA (Hip-Knee-Ankle angle), MPTA (Medial Proximal Tibial angle), LDFA (Lateral Distal Femoral Angle), JLO (Joint Line Obliquity), and JLCA (Joint Line Convergence Angle) were evaluated. The Knee injury and Osteoarthritis Outcome Score (KOOS), the International Knee Society (IKS) Function and Knee Score, and the Subjective Knee Value (SKV) as well as revision-free survival were evaluated. Postoperative alignment and its influence on clinical outcomes were also analysed.

RESULTS

The mean follow-up was 61.9 months ± 31.4 (13-124). The HKA, MPTA, and JLCA angles were decreased post-operatively (respectively, Δ = 5.9° ± 2.6, p < 0.001; Δ = 6.1° ± 3.2, p < 0.001 and Δ = 2.5° ± 1.9, p < 0.001). LDFA and JLO were unchanged, post-operatively (respectively, Δ = 0.1° ± 2.2, p = 0.93 and Δ = 1.2° ± 3.3, p = 0.23). Postoperative HKA correlated with knee IKS (R = - 0.15, p = 0.04) and function IKS (R = - 0.44, p = 0.03). Postoperative LDFA correlated with knee IKS(R = 0.8, p < 0.01). Patients with postoperative HKA ≤ 180° had better KOOS (Δ = 12.3, p = 0.04) and IKS function (Δ = 28.1, p < 0.01) than those with HKA > 180°.

CONCLUSION

Functional results and revision-free survival after MCWHTO are satisfactory when the deformity is located in the proximal tibia. The joint line obliquity is not significantly altered with small tibial correction and, obtaining an overall neutral or slightly varus alignment under the conditions of this study allowed an improvement in the postoperative clinical scores. The literature is still inconclusive on the ideal alignment for valgus deformities and larger series are needed to draw definitive conclusions.

LEVEL OF EVIDENCE

IV, case series.

The effect of weight-bearing positions on coronal lower limb alignment: A systematic review

BACKGROUND

The coronal alignment of the lower limb is generally accepted as a major determinant of surgical outcome in total knee arthroplasty (TKA). To achieve the ideal post-operative alignment, surgeons need to be aware of the influence that weight-bearing positions have on the final knee alignment. Therefore, this review aims to define the effect of varying weight-bearing positions on the coronal alignment of the lower limb. We hypothesized that a coronal alignment deformity increases with loading.

METHODS

The PubMed, Medline and google scholar databases were searched systematically in June 2022. Only studies which compared coronal alignment with a standardized radiographic protocol in the single leg, double leg and supine positions were included. To obtain pooled estimates of the effect of different weight-bearing positions, random-effect analysis were fitted using SAS.

RESULTS

Compared to the supine position, double leg weight-bearing positions were found to be associated with a more pronounced varus deformity (mean difference in HKA is 1,76° (95% CI 1,32: 2,21), p < 0.0001)). The mean difference in HKA between double leg and single leg weight-bearing conditions was 1.43° (95% CI (-0,042;2,90), p = 0.0528).

CONCLUSION

The overall knee alignment was found to be influenced by the weight-bearing position. An average difference of 1.76° in HKA-angle was found between a double leg-stance and supine position, tending to increased varus in the former weight-bearing position. It is therefore possible that the deformity could increase by 1.76° if knee surgeons only follow a pre-op planning based on double-leg stance full length radiographs.

Assessment of joint line obliquity and its related frontal deformity using long-standing radiographs

Purpose

To investigate how radiographic techniques and osteoarthritis grade influence measurements of knee joint line obliquity (KJLO) and KJLO-related frontal deformity, and to propose preferable KJLO measurement methods.

Methods

Forty patients with symptomatic medial knee osteoarthritis indicated for high tibial osteotomy were assessed. Measurements were compared between single-leg and double-leg standing radiographs for KJLO measurement methods including joint line orientation angle by femoral condyles (JLOAF), joint line orientation angle by middle knee joint space (JLOAM), joint line orientation angle by tibial plateau (JLOAT), Mikulicz joint line angle (MJLA) and medial proximal tibial angle (MPTA), as well as KJLO-related frontal deformity parameters including joint line convergence angle (JLCA), knee ankle joint angle (KAJA) and hip-knee-ankle angle (HKA). Influences of bipedal distance in double-leg standing and osteoarthritis grade on the above measurements were analysed. Measurement reliability was evaluated by intraclass correlation coefficient.

Results

From single-leg to double-leg standing radiographs MPTA and KAJA did not change significantly, whereas the other measurements showed significant changes: JLOAF, JLOAM and JLOAT decreased 0.88°, 1.24° and 1.77°, MJLA and JLCA decreased 0.63° and 0.85°, and HKA increased 1.11° (p < 0.05). Bipedal distance in double-leg standing radiographs moderately correlated with JLOAF, JLOAM and JLOAT (rp = -0.555, -0.574 and -0.549). Osteoarthritis grade moderately correlated with JLCA in single-leg and double-leg standing radiographs (rs = 0.518 and 0.471). All measurements had at least good reliability.

Conclusion

In long-standing radiographs, measurements of JLOAF, JLOAM, JLOAT, MJLA, JLCA and HKA are all influenced by single-leg/double-leg standing; JLOAF, JLOAM and JLOAT are also affected by bipedal distance in double-leg standing; and JLCA is affected by osteoarthritis grade. Knee joint obliquity as assessed by MPTA measurement is independent of single-leg/double-leg standing, bipedal distance or osteoarthritis grade, and has excellent measurement reliability. We therefore propose MPTA as the preferable KJLO measurement method for clinical practice and future research.

Level of evidence

III, cross-sectional study.

Can double-level osteotomy prevent patellofemoral osteoarthritis progression compared with open wedge high tibial osteotomy?

PURPOSE

To compare radiographic, clinical, and arthroscopic findings in patellofemoral (PF) osteoarthritis (OA) between open wedge high tibial osteotomy (OWHTO) and double-level osteotomy (DLO) with the same operative indication.

METHODS

After adjustment for patient age, and coronal alignment, 36 knees with OWHTO alone and 36 knees with DLO were compared. Radiographic, clinical, and arthroscopic findings were documented before osteotomy. Arthroscopic findings were observed 1 year after osteotomy, and clinical and radiographic findings were observed 2 years after osteotomy. Patellar height was evaluated using the Insall-Salvati (IS) ratio, Carton-Deschamps (CD) index, and Blackburne-Peel (BP) index. Lateral patellar tilt and patellar shift were measured. A power analysis was performed.

RESULTS

The postoperative CD and BP indices in the OWHTO group were lower than those in the DLO group (p < 0.001 and p = 0.001, respectively). The CD and BP indices in both groups significantly decreased postoperatively (all p < 0.001). Tilting angles in the OWHTO and DLO groups significantly decreased postoperatively (p < 0.001 and p = 0.002, respectively). There were no significant differences in American Knee Society scores, Kujala score, and the Knee Injury and Osteoarthritis Outcome Scores between both groups. The PF OA progression of the trochlear in the OWHTO group was higher than that in the DLO group (p = 0.002), and the PF OA progression of the patellar facet in the DLO group and anterior femoral condyle in both groups on the lateral side were higher than those on the medial side (p = 0.006, 0.032, and 0.041, respectively).

CONCLUSIONS

DLO decreased the rate of low patellar height compared with OWHTO. DLO decreased the rate of PF OA progression in the trochlea compared with OWHTO. There were no significant differences in clinical outcomes in both groups.

LEVEL OF EVIDENCE

Level III, case-control study.

Factor affecting the discrepancy in the coronal alignment of the lower limb between the standing and supine radiographs

BACKGROUND

Conflicting results have been reported regarding the factors that can predict the discrepancy in the coronal alignment of the lower limb between radiographs taken in the standing and supine positions. Therefore, this study aimed to investigate factors that can predict discrepancies in the coronal alignment of the lower limb between radiographs taken in the standing and supine positions.

METHODS

We retrospectively evaluated the medical records of patients who underwent full-length anteroposterior radiographs of the lower limb in both standing and supine positions between January 2019 and September 2021. The discrepancy in the coronal alignment of the lower limb between the standing and supine radiographs was defined as the absolute value of the difference in the hip-knee-ankle (HKA) angle between the two radiographs, which is presented as the ΔHKA angle. Correlation and regression analyses were performed to analyse the relationship among ΔHKA angle, demographic data, and several radiographic parameters.

RESULTS

In total, 147 limbs (94 patients) were included in this study. The mean ΔHKA angle was 1.3 ± 1.1° (range, 0-6.5°). The ΔHKA angle was significantly correlated with body mass index and several radiographic parameters, including the HKA angle, joint line convergence angle, and osteoarthritis grade. Subsequent multiple linear regression analysis was performed using the radiographic parameters measured on the supine radiographs with the two separate models from the two observers, which revealed that body mass index and advanced osteoarthritis (Kellgren-Lawrence grades 3 and 4) had a positive correlation with the ΔHKA angle.

CONCLUSIONS

Body mass index and advanced osteoarthritis affected the discrepancy in the coronal alignment of the lower limb between standing and supine radiographs. A discrepancy in the coronal alignment of the lower limb could be more prominent in patients with an increased body mass index and advanced osteoarthritis, corresponding to Kellgren-Lawrence grades 3 and 4.

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.