Joint line obliquity after lateral closing-wedge high tibial osteotomy does not adversely affect clinical and radiological outcome: a 5-year follow-up study

Joint-line obliquity angle is significantly affected by hip abduction and adduction: A simulated analysis

PURPOSE

Different methods for quantifying joint-line obliquity (JLO) have been described, including joint-line obliquity angle (JLOA), Mikulicz joint-line angle (MJLA) and medial proximal tibial angle (MPTA). The goal of the present study was to quantify the variation of JLOA based on the position of the hip. The hypothesis of our study is that JLO is significantly influenced by the abduction/adduction of the limb, unlike MJLA.

METHODS

One hundred long-leg-weightbearing X-rays were used. At time 0 and after 30 days, two observers performed different measurements, including (1) distance between pubic symphysis and center of the femoral head, (2) distance between center of the femoral head and center of the ankle joint, (3) distance between center of the ankle and medial malleolus, (4) hip-knee-ankle angle, (5) MPTA, (6) lateral distal femoral angle, (7) joint-line congruency angle, (8) JLOA, (9) MJL and (10) angle between Mikulicz line and line perpendicular to the ground. The changes of the JLOA based on the position of the hip (abducted, neutral, bipedal stance adduction and monopodal stance adduction) were calculated with trigonometric formulas and with simulation on an orthopaedic planning digital software.

RESULTS

The JLOA change between adducted and abducted positions was on average 12.8° (SD 0.9 mm). The MJL did not vary significantly based on hip position.

CONCLUSIONS

The adduction/abduction of the lower limb has a considerable impact on JLOA. Methods like MJLA which are not affected by hip position should be preferred for JLO evaluation.

LEVEL OF EVIDENCE

Diagnostic study, level III.

Influence of Increased Joint Line Obliquity on Survivorship After Lateral Closing-Wedge High Tibial Osteotomy

BACKGROUND

Although high tibial osteotomy (HTO) has emerged as a powerful intervention for treating symptomatic medial osteoarthritis and varus malalignment, it can result in an increase in knee joint line obliquity (KJLO) in the frontal plane. Limited current evidence hinders understanding of the effect of increased KJLO on HTO survivorship.

PURPOSE

To investigate the influence of KJLO and other potential risk factors on the survivorship of lateral closing-wedge HTO.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients with symptomatic medial knee osteoarthritis and varus malalignment treated with lateral closing-wedge HTO at a single hospital were screened with a minimum follow-up of 5 years. HTO survival rate was assessed using Kaplan-Meier survival analysis. The influence of postoperative increased KJLO (medial proximal tibial angle ≥95°), age (≥55 years), sex (female), preoperative malalignment (hip-knee-ankle angle ≥10° of varus), postoperative untargeted alignment (hip-knee-ankle angle <2° or >6° of valgus), and preoperative osteoarthritis severity (Kellgren-Lawrence grade ≥3) on survivorship of HTO was evaluated using Cox regression analysis. A failure of HTO was defined as a conversion to total knee arthroplasty (TKA).

RESULTS

A total of 410 patients (463 knees) were included, with a mean follow-up of 13.0 years (range, 5.0-18.1 years) and a mean survival time of 11.2 years (range, 1.2-18.1 years) for patients who reached the endpoint of TKA. HTO survival rates at 5, 10, and 15 years postoperatively were 91%, 78%, and 60%, respectively. Multivariate Cox regression analysis showed no significant difference in survivorship between patients with increased KJLO and those with acceptable KJLO (178 vs 285 knees; hazard ratio [HR], 0.8; 95% CI, 0.6-1.1; P = .148), with no significant between-group difference observed in the mean follow-up length (12.9 ± 3.0 years vs 13.1 ± 3.3 years; P = .105). Female sex (HR, 2.0; P < .001) and postoperative untargeted alignment (HR, 1.6; P = .003) were risk factors for a conversion to TKA.

CONCLUSION

Increased postoperative KJLO (medial proximal tibial angle ≥95°) had no significant influence on the survivorship of lateral closing-wedge HTO. Men demonstrated superior survival outcomes compared with women, and it was important to achieve a targeted postoperative alignment (HKA 2°-6° of valgus) to ensure favorable HTO survivorship.

Around-the-knee osteotomies part 1: definitions, rationale and planning-state of the art

Knee osteotomies are essential orthopedic procedures with the ability to preserve the joint and correct ligament instabilities. Literature supports the correlation between lower limb malalignment and outcomes after knee ligament reconstruction and cartilage procedures. Concepts such as joint line obliquity, posterior tibial slope angle, and intra-articular deformity correction are integral components of both preoperative planning and postoperative evaluations. The concept of preserving and/or restoring joint line congruence during simultaneous correction of varus or valgus deformity can be achieved through several different approaches. With advancements in osteotomy research and surgical planning technology, the surgical decision-making has increased in complexity. Based upon a patient's specific deformity, decisions need to be made whether to perform a single-level (proximal tibia or distal femur) versus double-level (both proximal tibia and distal femur) osteotomy, and whether to correct deformity in a single plane (coronal or sagittal) or perform a biplanar osteotomy, correcting two of the malalignments in either coronal, sagittal, or axial planes. Osteotomy procedures prioritize safety, reproducibility, precision, and meticulous planning. Equally important is the proactive management of possible complications and the implementation of preventive strategies for complications such as hinge fractures and unintentional changes to alignment in other planes. This review navigates the intricate landscape of lower limb alignment, commencing with foundational definitions and rationale for performing osteotomies, progressing through the planning phase, and addressing the critical aspect of complication prevention, all while looking ahead to anticipate future advancements in this field. However, rotational osteotomies and tibial tubercle osteotomies in isolation or as an adjunct procedure are beyond the scope of this review.

Preoperative joint line obliquity, a newly identified factor for overcorrection, can be incorporated into a novel preoperative planning method to optimise alignment in high tibial osteotomy

PURPOSE

The aim of this study was to analyse the factors associated with additional postoperative alignment changes after accurate bony correction by selecting only patients with well-performed bony correction as planned and develop a method of incorporating significant factors into preoperative planning.

METHODS

Among 104 consecutive patients who underwent medial open wedge high tibial osteotomy (MOWHTO) between October 2019 and July 2022, 61 with well-performed bony corrections were retrospectively reviewed. The major criterion for well-performed bony correction was a difference of <1° between the simulated medial proximal tibial angle (MPTA) and the actual postoperative MPTA as measured in three dimensions. Radiographic parameters, such as the joint line convergence angle (JLCA) and joint line obliquity (JLO), were measured preoperatively and postoperatively, utilising standing and supine whole lower extremity anteroposterior, valgus and varus stress radiographs. Multiple linear regression analysis identified the factors affecting alignment changes, and a prediction model was developed. A method for applying this prediction model to preoperative planning was proposed.

RESULTS

Preoperative JLCA on standing (preJLCAstd ), preoperative JLCA on 0° valgus stress radiograph (vgJLCA0 ), and preoperative JLO (preJLO) were significantly correlated with JLCA change (∆JLCA) (p < 0.001, p < 0.001, p = 0.006). The prediction model was estimated as ∆JLCA = 0.493 × (vgJLCA0 ) - 0.727 × (preJLCAstd ) + 0.189 × (preJLO) - 1.587 in. (R = 0.815, modified R2  = 0.646, p < 0.001). The proposed method resulted in a reduced overcorrection rate (p = 0.003) and an improved proportion of acceptable alignments (p = 0.013).

CONCLUSION

PreJLCAstd , vgJLCA0  and preJLO can be used to estimate ∆JLCA. PreJLO was recently identified as a significant factor associated with additional alignment changes. Utilising the proposed preoperative planning and a prediction model with these factors shows promise in calibrating postoperative alignment after MOWHTO.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.