Radiological, functional, and anatomical outcome in patients with osteoarthritic knee undergoing high tibial osteotomy

Compensatory mechanisms for proximal & distal joint alignment & gait in varus knee osteoarthritis treated with high tibial osteotomy: A systematic review

Background

Varus deformity is common in medial compartment knee osteoarthritis (OA). This coronal plane malalignment is compensated for by static and dynamic adjustments in the position of the adjacent joints, principally in the hindfoot & ankle. Varus knee OA can be treated in selected patients with high tibial osteotomy (HTO) and stabilised with a fixed angle plate or circular frame, which may reverse these compensatory adjustments. The aim of this systematic review is to determine the evidence available for static and dynamic compensations with the main objectives being to improve deformity planning and optimise patient outcomes.

Method

A systematic review with meta-analysis was designed using the PRISMA template to meet the research aims & objectives.

Results

A total of 1006 patients (1020 knees) with acombined mean age of 54.5 years, female:male ratio of 0.9:1 were extracted from 19 included studies. The methodologies of the majority of studies were at high risk of bias according to the Newcastle-Ottawa Scale demonstrating significant heterogeneity. The combined mean change in the HKA axis was 7.7°; MPTA 7.4°; TT, 0.21°; TI 4.56° & AJLO 4° valgus. Preoperative hindfoot valgus compensation reverts towards neutral post-HTO. There is limited evidence available for a direct relationship between static alignment and dynamic gait parameters.

Conclusions

An inverse relationship between ankle and hindfoot alignment in varus deformity of the knee forms the basis of this compensation theory. In cases with a stiff hindfoot which may not revert postoperatively, the reconstructive orthopaedic surgeon may consider angulation with translation HTO, in order to optimise joint alignment and minimise transference of symptoms to the foot and ankle.

Changes in sagittal and axial plane alignment in medial opening wedge high tibial osteotomy: a prospective observational study

PURPOSE

Deformity correction during high tibial osteotomy is generally based on coronal plane alignment. The aim of this study was to measure changes in sagittal and axial plane alignment following medial opening wedge high tibial osteotomy [mHTO], using pre- and postoperative computed tomography [CT] scans, and correlate them with changes in coronal plane. The secondary objective was to correlate changes in functional outcomes with changes in alignment in each plane. The null hypothesis was that sagittal and axial plane alignment does not change significantly following mHTO.

METHODS

This was a prospective, observational study including 30 patients of isolated medial compartment osteoarthritis of the knee joint, between 30 and 60 years of age. Preoperative and postoperative computed tomography scan of bilateral lower limbs from hip to ankle was performed. Varus angle, mechanical axis deviation [MAD] of the lower limb, medial proximal tibial angle [MPTA], tibial torsion and posterior proximal tibial angle [PPTA] were measured. Visual Analogue Scale [VAS 0-10 cm scale] was used for assessment of pain. Functional outcomes were evaluated using Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], 12 Item Short Form Survey [SF 12] and Tegner Lysholm knee scoring scale.

RESULTS

Mean age of patients was 44.59 ± 8.157 years. Mean preoperative varus deformity was 11.13 ± 1.5 degrees, which got corrected to a mean valgus alignment of 3.8 ± 0.93 degrees postoperatively. The mechanical axis deviation was 4.32 ± 1.76 mm lateral to the knee joint center postoperatively. Preoperatively, all knees had external tibial torsion [27.08 ± 2.18 degrees] which was corrected to a mean external tibial torsion of 19.80 ± 3.72 degree after the surgery [P < 0.001]. The overall decrease in sagittal alignment in the present study was 3.70 ± 3.14 degree, 3.97 ± 3.06 degree, 3.92 ± 2.33 degree, for medial, middle and lateral cuts, respectively. There was a significant correlation between change in varus/valgus angle and change in TT and PPTA. Significant positive correlation was seen between change in coronal alignment and functional outcome scores.

CONCLUSION

This study has shown that mHTO significantly changes torsional and sagittal alignment. This is the first study to establish relation between correction in coronal plane and associated changes in sagittal and torsional alignments.

Gait analysis and knee kinematics before, and 6 and 18 months after corrective valgus osteotomy

BACKGROUND

The study objective was to assess clinical outcomes and gait biomechanics in patients after 6 and 18 months after varus deformity (VD) surgical correction at knee joint (KJ).

METHOD

The study included 20 patients with medial osteoarthritis (OA) of the knee of grade 2-3 and a VD of >4°. A total of 21 surgeries were performed on the patients. Full length weight bearing (FLWB) X-ray and KJ assessments were done using the KSS, KOOS and VAS scoring systems were obtained from all the patients. Biomechanical gait parameters were captured using an inertial sensor system at timepoints before, and 6 and 18 months after surgery. Temporal and kinematic parameters of walking were analyzed.

RESULTS

The radiological parameters showed a stable VD correction. According to the KOOS, KS and VAS scores, there was a moderate dynamic improvement in the operated knee function during the study. The biomechanical parameters remained virtually unchanged throughout the entire follow-up period. In the following year, there were some subjective improvements but without any significant changes in gait biomechanics or knee kinematics.

CONCLUSIONS

Thus, the main changes in the joint clinical condition and function occur in the first 6 months after surgery. According to the study data-assessments by VAS, KOOS, and KSS-there was a moderate clinical improvement during the long-term follow-up period, however, the biomechanical changes were minor.