The Influence of Knee Osteoarthritis on Spinopelvic Alignment and Global Sagittal Balance

Impact of Knee Osteoarthritis and Arthroplasty on Full-body Sagittal Alignment in Adult Spinal Deformity Patients

STUDY DESIGN

Retrospective analysis of prospectively collected data.

OBJECTIVE

This study evaluates the impact of knee osteoarthritis (OA) and knee arthroplasty on alignments and patient-reported outcomes measures (PROMS) of patients undergoing adult spinal deformity (ASD) corrective surgery.

BACKGROUND

The relationship between knee OA and spinal alignment in patients with ASD is incompletely understood. It is also unknown how patients with knee arthroplasty and ASD compare to ASD patients with native knees.

METHODS

Baseline full-body radiographs were used, and hip and knee OA were graded by two independent reviewers using the KL classification. Spinopelvic parameters and PROMs were compared across the different knee OA groups and compared between patients with knee replacement and native knees.

RESULTS

One hundred ninety-nine patients with bilateral nonsevere OA (G1), 31 patients with unilateral severe knee OA (G2), and 60 patients with bilateral severe knee OA (G3). Patients with severe knee OA presented with worse spinopelvic parameters. However, after multivariable regression analysis controlling for age, frailty, PI, T1PA, knee OA was an independent predictor of knee flexion (G1: -0.02±7.3, G2: 7.8±9.4, G3: 4.5±8.7, P <0.001), and ankle dorsiflexion (G1: 2.3±4.0, G2: 6.6±4.5, G3: 5.1±4.1, P <0.001). There was no difference in PROMs ( P >0.05). Secondary analysis included 96 patients: 48 patients (50%) with nonsevere knee OA, and 48 patients (50%) with knee replacement. There was no difference in radiographic parameters or PROMs between the groups.

CONCLUSIONS

In this study of complex ASD patients, patients with worse spinal deformities were more likely to have concomitant knee OA. Knee OA was shown to be a predictor of knee flexion and ankle dorsiflexion angles, but was not associated with worse PROMs in this study population. Patients with knee arthroplasty, however, had comparable spinal alignment and PROMs relative to those with mild OA.

Impact of skeletal muscle mass of the trunk and extremities on standing spine parameters before and after surgery for adult spinal deformity with a minimum 2-year follow-up

PURPOSE

The effect of skeletal muscle mass of the trunk and extremities on sagittal imbalance of the spine before and after surgery for adult spinal deformity (ASD) has not been elucidated. The purpose of this study was to examine the correlation between reduced skeletal muscle mass of the trunk and extremities, as well as spinopelvic parameters, preoperatively, postoperatively and at least 2 years after surgery for ASD.

METHODS

This retrospective observational study included 140 consecutive patients who had undergone surgery for ASD and were followed-up for at least 2 years and whose skeletal muscle mass could be measured preoperatively using whole-body dual-energy X-ray absorptiometry. Correlations between skeletal muscle mass and spinopelvic parameters were assessed preoperatively, postoperatively, and after 2 years of follow-up.

RESULTS

All spinopelvic parameters were significantly improved postoperatively compared with preoperatively. Between the postoperative period and two years post-surgery, a significant loss of correction was observed in SVA and GT. Trunk muscles mass showed significant negative correlations with preoperative PT, SS, PI-LL, SVA, GT, and TPA, but there was no significant correlation with postoperative parameters. Through univariate and multivariate regression analysis, lower limb skeletal muscle mass showed a significant negative correlation with SVA at two years postoperatively and the loss of corrected SVA (ΔSVA) over two years.

CONCLUSION

This study revealed that lower extremity muscle mass was implicated in the loss of corrected SVA 2 years after surgery. This study is clinically meaningful as it suggests that strength training for the lower extremities, performed preoperatively and/or postoperatively, can improve sagittal imbalances of the spine in patients with severe ASD or maintain SVA after corrective surgery.

LEVEL OF EVIDENCE: 3

Changes in spino-pelvis-lower extremity alignment in patients with knee osteoarthritis: a prospective radiographic study

PURPOSE

Osteoarthritis (OA) is a prevalent, debilitating ailment among the elderly. Humans need a correct sagittal spino-pelvis-lower extremity alignment to stand upright. Pathology in trunk or lower extremity section might disrupt this harmony, causing compensatory alterations in other segments. The aim of the present study was to evaluate spino-pelvis-lower extremity alignment and association among the various spino-pelvic, knee, and ankle radiological angles in patients with knee osteoarthritis (OA).

MATERIALS AND METHODS

This prospective study enrolled 70 adults over 50 years of age of either sex who complained of knee pain and met the American College of Rheumatology criteria for symptomatic OA of at least one knee. The radiological assessment comprised anteroposterior and lateral lower extremity full-length scans, as well as the Kellgren-Lawrence radiographic classification of OA. We measured hip, knee, ankle, and spino-pelvic angles using Horos software. We calculated descriptive statistics and linear correlation between continuous variables.

RESULTS

There was a significant association (p < 0.05) between age and the majority of the spino-pelvic, knee, and ankle angles and between age and severity of OA. Significant variables linked with 'SFA' include HKAA (p = 0.008), mLDFA (p < 0.001), TJLA, FS-TS, Cond-Plateau, and femoral bowing (p = 0.007). We found significant associations between 'PFA' and mMPTA (p = 0.005), Cond-Plateau (p = 0.005), Tibial Bowing (p = 0.003), and 'LL' with HKAA, mLDFA, FS-TS, and Cond-Plate. SSA was significantly associated with mLDFA, mMPTA, TJLA, Cond-Plateau, and HKAA; while, FI' was significantly associated with FS-TS, femoral bowing, and tibial bowing (p < 0.001). The variables 'SS' was substantially linked with TTA (p = 0.008), TT (p = 0.004), PP (< 0.001), GP (p < 0.001), and GT (p = 0.010). 'PI' was substantially linked to TT (p = 0.001), GP (p = 0.005), and GT (p = 0.042), and 'PT' to TT (p < 0.001) and GT (p = 0.012). 'SFA' and 'PFA' only correlated with TT (p = 0.012 and 0.010). Lower limb angles were significantly associated with TT, PP, GP, GT, mLDFA, and mMPTA (p = 0.031, p = 0.026, p = 0.009, p = 0.009, TT, GP, GT, p < 0.001). GP was the sole significant association for 'TJLA' (p = 0.016). 'FS-TS' substantially correlated with PP (p = 0.015), GP (p < 0.001), and GT (p < 0.001). "Femoral Bowing" was significantly linked to PP (p = 0.017), GP (p = 0.007), and GT (p < 0.001), and "Cond-Plateau" was significantly linked to GP (p = 0.002) and GT. "Tibial Bowing" was significantly linked to TTA (p < 0.001), TAS (p = 0.003), LDTA (p = 0.002), TC (p < 0.001), GP (p = 0.007), and GT (p < 0.001). Age, gender, BMI, and the severity of knee OA significantly influenced the association among these various angles.

CONCLUSION

Osteoarthritis of the knee disrupts the harmonious alignment of the spine and pelvis with the lower limbs, resulting in compensatory changes in the ankle and spine. The severity of knee osteoarthritis and the patient's gender, age, and BMI impact compensatory adaptations.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

CTRI/2021/08/036088 [Registered on: 31/08/2021] - Trial Registered Prospectively.

The spinopelvic alignment in patients with prior knee or hip arthroplasty undergoing elective lumbar surgery

BACKGROUND CONTEXT

Concurrent degeneration of the lumbar spine, hip, and knee can cause significant disability and lower quality of life. Osteoarthritis in the lower extremities can lead to movement limitations, possibly requiring total knee arthroplasty (TKA) or total hip arthroplasty (THA). These procedures often impact spinal posture, causing alterations in spinopelvic alignment and lumbar spine degeneration. It is unclear if patients with a history of prior total joint arthroplasty (TJA) have different spinopelvic alignment compared to patients without.

PURPOSE

To assess the relationship between a history of previous THA or TKA, as well as combined THA and TKA, and the spinopelvic alignment in patients undergoing elective lumbar surgery for degenerative conditions.

STUDY DESIGN

A retrospective analysis was conducted on patients who underwent lumbar surgery for degenerative conditions. The patients were stratified based on a history of TKA, THA, or both TKA and THA.

PATIENT SAMPLE

A total of 632 patients (63% female) with an average age of 64±11 years and an average BMI of 30±6 kg/m2 were included.

OUTCOME MEASURES

Patients were stratified based on a history of THA, TKA, or combined THA and TKA. Spinopelvic parameters (lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI)) were assessed. The relationship between spinopelvic alignment and prior TKA, THA or TKA and THA was analyzed.

METHODS

The data was tested for normal distribution using the Shapiro-Wilk test. We analyzed the relationship between the spinopelvic parameters and the different arthroplasty groups. Differences in scores between groups were examined using ANOVA. Tukey's Honestly Significant Difference test was used for pairwise comparison for significant ANOVA test results. Multivariable linear regression was applied, adjusted for age, sex and BMI.

RESULTS

A total of 632 patients (63% female) were included in the study. Of these patients, 74 (12%) had a history of isolated TKA, 40 (6%) had prior isolated THA, and 15 (2%) had TKA and THA prior to lumbar surgery. Patients with prior arthroplasty were predominantly female (59%) and significantly older (68±7 years vs 63±12 years, p<.001) with a significantly higher BMI (31±6 kg/m2 vs 29±6 kg/m2, p<.001). The LL was significantly lower (45.0°±13 vs 50.9°±14 p=.011) in the arthroplasty group compared to the nonarthroplasty group. A history of isolated TKA was significantly associated with lower LL (Est=-3.8, 95% CI -7.3 to -0.3, p=.031) and SS (Est=-2.6, 95% CI -5.0 to -0.2, p=.012) compared to patients without TJA. Prior combined THA and TKA was found to be significantly associated with a higher PT compared to the nonarthroplasty group (Est=5.1, 95% CI 0.4-9.8, p=.034).

CONCLUSIONS

The spinopelvic alignment differs between patients with and without prior TJA who undergo elective lumbar surgery. The study shows that a history of TKA is significantly associated with a lower LL and SS. The combination of THA and TKA was associated with a significantly higher PT. These findings highlight the complex relationship between the hip, spine, and knee. Moreover, the results could aid in enhancing preoperative planning of lumbar surgery in patients with known TJA.

Changes in spinal sagittal balance after a new osteoporotic vertebral compression fracture

We conduct a longitudinal study to examine how new VCF alter spinal sagittal balance. New VCF increased SVA by an average of 2.8 cm. Sagittal balance deteriorates as a VCF develops in the lower lumbar spine. A new fracture below L1 increased the relative risk of a deterioration of sagittal balance 2.9-fold compared to one above Th12.

PURPOSE

Studies on the relationship between osteoporotic vertebral fractures and spinal sagittal balance have all been limited to cross-sectional studies. The aim of this study is to conduct a longitudinal study to examine how new vertebral compression fracture (VCF) alter spinal sagittal balance.

METHODS

Subjects were patients undergoing periodic examinations after treatment of a vertebral fracture or lumbar spinal canal stenosis. Forty patients who developed a new VCF were included in this study. Full-spine standing radiographs were compared before and after the fracture to examine changes in spinopelvic parameters and factors determining the changes in sagittal balance.

RESULTS

The mean age of the patients was 79.0 years. The mean interval between pre- and post-fracture radiographs was 22.7 months, and the mean time between development of a fracture and post-fracture radiographs was 4.6 months. After a fracture, sagittal vertical axis (SVA) increased an average of 2.78 cm and spino-sacral angle (SSA) decreased an average of 5.3°. Both ⊿SVA and ⊿SSA were not related to pre-fracture parameters. The wedge angle of the fractured vertebra was not related to changes in sagittal balance. ⊿SVA increased markedly in patients with a fracture of the lower lumbar vertebrae. receiver operating characteristic analysis revealed that the relative risk of a deterioration of sagittal balance was 2.9 times higher for a new fracture below L1 than for a fracture above Th12.

CONCLUSION

New VCF increased SVA by an average of 2.8 cm. Sagittal balance deteriorates as a new fracture develops in the lower lumbar spine. Early intervention in osteoporosis is vital for the elderly.

Contralateral knee osteoarthritis is a risk factor for ipsilateral knee osteoarthritis progressing: a case control study

BACKGROUND

Knee osteoarthritis (KOA) is a highly disabling disease, and studying its progression is crucial. However, it is still unclear whether the progression of ipsilateral knee osteoarthritis is influenced by contralateral knee osteoarthritis.

METHODS

Data were collected from the OAI database and divided into two study cohorts (right/left KOA cohort). Each cohort had a target knee (right/left knee) and was further divided into two groups (exposure/control group). The demographic data of both cohorts were balanced at baseline by propensity score matching (PSM), and the data included rating scale and radiographic and clinical data. After checking for balance in the matched variables, we then compared the differences between the two groups in each cohort. Our primary focus was on the minimum joint space width (mJSW) of the target knee, which was measured four years after baseline. The secondary outcome was the arthroplasty rate of the target knee within nine years.

RESULTS

In this study, a total of 678 participants were enrolled and matched. After 1:1 PSM of the baseline demographic data, 98 participants in the right KOA cohort (RKOAC) were successfully matched, and 117 participants in the left KOA cohort (LKOAC) were successfully matched. Furthermore, the standardized mean difference (SMD) of the matched variables in both cohorts was less than 0.25. After analyzing the outcome metrics, we found that the target knee had a significantly lower mJSW in the fourth year after baseline and a significantly greater arthroplasty rate within nine years in the exposed group than in the control group. RKOAC: mJSW (exposure: 2.6(1.1 ~ 3.6) vs. control: 3.3(2.0 ~ 4.2), P < 0.05), arthroplasty rate (exposure: 14(14.3%) vs. control: 4(4.1%), P < 0.05); LKOAC: mJSW (exposure: 3.1(2 ~ 3.9) vs. control: 3.4(2.6 ~ 4.2), P < 0.05), arthroplasty rate (exposure: 16(13.7%) vs. control: 7(6%), P < 0.05).

CONCLUSIONS

Patients with knee osteoarthritis experienced greater progression of osteoarthritis when the contralateral knee was also affected.

Comparison of the plantar pressure distribution and mechanical alignment in patients with varus knee osteoarthritis following high tibial osteotomy

PURPOSE

The changes in the lower limb alignment were vitally important after high tibial osteotomy (HTO). Therefore, the purpose of present study was to analyze the characteristics of plantar pressure distribution after HTO, and to investigate the effect of plantar pressure distribution on postoperative limb alignment.

METHODS

Between May 2020 and April 2021, varus knee patients undergoing HTO were evaluated in the present study. The peak pressure of plantar regions, medial-lateral pressure ratio (MLPR), foot progression angle (FTA), anteroposterior COP (AP-COP), lateral symmetry of COP (LS-COP), and the radiographic parameters were evaluated preoperatively and at the final follow-up. Compared among the slight valgus (SV), moderate valgus (MV) and large valgus (LV) groups at the final follow-up, the peak pressure of HM, HC and M5 regions, and the MLPR were compared; the Knee Injury and Osteoarthritis Outcome Score4 (KOOS4) including four subscales, and the American of orthopedic foot and ankle society (AOFAS) were evaluated.

RESULTS

The WBL%, HKA and TPI angle changed significantly after HTO (P < 0.001). The preoperative group exhibited a lower peak pressure in the HM region (P < 0.05) and higher peak pressure in the M5 region (P < 0.05); the pre- and postoperative groups exhibited a lower peak pressure in the HC region (P < 0.05); the rearfoot MLPR was significantly lower and LS-COP was significantly higher in the preoperative group (P = 0.017 in MLPR and 0.031 in LS-COP, respectively). Comparison among the SV, MV and LV groups, the SV group indicated a lower peak pressure in the HM region (P = 0.036), and a lower MLPR in the rearfoot (P = 0.033). The KOOS Sport/Re score in the MV and LV groups increased significantly compared with the SV group (P = 0.042).

CONCLUSION

Plantar pressure distribution during the stance phase in patients with varus knee OA following HTO exhibited a more medialized rearfoot plantar pressure distribution pattern than that before surgery. Compared with the small valgus alignment, a moderate to large valgus alignment allows patients to walk with a more even medial and lateral plantar pressure distribution, which is more similar to healthy adults.

From the Spinopelvic Parameters to Global Alignment and Proportion Scores in Adult Spinal Deformity

In the last 20 years, sagittal alignment and balance of the spine have become one of the most important issues in the field of spine surgery. Recent studies emphasize that sagittal balance and alignment are more important for health-related quality of life. The understanding of normal and abnormal sagittal alignment of the spine is necessary for the diagnosis and appropriate treatment of adult spinal deformity (ASD), and we will discuss the currently used classification of ASD, the parameters of sagittal alignment that are essential for the diagnosis of spinal deformity, compensatory actions to maintain sagittal balance, and the relationship between sagittal alignment and clinical symptoms. Furthermore, we will also discuss the recently introduced Global Alignment and Proportion scores. The Korean Spinal Deformity Society is publishing a series of review articles on spinal deformities to help spine surgeons better understand spinal deformities.

The significance of the pelvic incidence measurement as a possible predictor of TKA outcome

PURPOSE

To evaluate the association between the sagittal alignment of the pelvis and residual knee flexion contracture after total knee arthroplasty (TKA). This is important as a flexion contraction can be associated with the risk of poor outcomes and patient satisfaction after TKA.

METHODS

This was a retrospective, case-control, study of 200 osteoarthritic knees, contributed by 200 patients, over a mean follow-up of 2.4 years. The following factors were compared between patients 'with' (46 knees) and 'without' (154 knees) a residual flexion contracture ≥ 10° after TKA: age, sex, pelvic incidence (PI), anterior femoral bowing, femoral component flexion angle (FFA), and patient-reported outcomes. Logistic regression and receiver operating characteristic curve analyses were used to identify predictive factors.

RESULTS

The following factors were predictive of a residual flexion contracture ≥ 10°: a pelvic incidence ≥ 55° (odds ratio, 1.29; 95% confidence interval, 1.05-1.59; P = 0.031) and the FFA (odds ratio, 1.08; 95% confidence interval, 1.03-1.14; P = 0.044). A pelvic incidence cutoff of 55° yielded a significant between-group difference, with a sensitivity of 78.4% and specificity of 89.9% to differentiate a residual knee flexion contracture ≥ 10° (P = 0.001), patient satisfaction (P = 0.029), EuroQol 5-Dimension score (P = 0.028), anterior femoral curvature (P = 0.031), and Knee Injury and Osteoarthritis Outcome Score-Joint Replacement score (P = 0.046).

CONCLUSION

A pelvic incidence > 55° is associated with a residual knee flexion contracture ≥ 10° after TKA. The significance of the pelvic incidence measurement as a possible predictor of TKA outcome was highlighted, including its impact on patient satisfaction.

LEVEL OF EVIDENCE

III.