Correlation between varus knee malalignment and patellofemoral osteoarthritis

Femorotibial angle scan-rescan reproducibility: A high-precision calculation on a large cohort

PURPOSE

Femorotibial angle (FTA) is a convenient measure of coronal knee alignment that can be extracted from a short knee radiograph, avoiding the additional radiation exposure and specialist equipment required for full-leg radiographs. While intra- and inter-reader reproducibility from the same image has been reported, the full scan-rescan reproducibility across images, as calculated in this study, has not.

METHODS

In this study, 4589 FTA measurement pairs from 2586 subjects acquired a year apart were used to estimate FTA scan-rescan reproducibility using data from the Osteoarthritis Initiative. Subjects with radiographic progression of osteoarthritis or other conditions that may cause a change in coronal knee alignment were excluded. Measurement pairs were analysed using paired-samples t $t$ tests to detect differences and compared to symptomatic changes in Western Ontario and McMaster Universities Arthritis Index scores for joint pain, stiffness and physical function to detect correlations.

RESULTS

The 95% limit of agreement and the paired-samples correlation were calculated with high precision to be [-1.76°, +1.78°] and 0.938, considerably worse than the corresponding figures for intra- and inter-reader reproducibility, without relation to symptomatic or radiographic changes in knee condition. This error will weakly attenuateR 2 ${R}^{2}$ andr $r$ values from their true values in correlative studies involving FTA. The realistic maximum value forR 2 ${R}^{2}$ is 87% and for Pearson'sr $r$ is 93%.

CONCLUSION

The scan-rescan reproducibility in FTA is almost double the intra- and inter-reader reliability from a single scan. At almost ±2° accuracy, FTA is inappropriate for surgical use, but it is sufficiently reproducible to produce good correlations in studies predicting disease incidence and progression.

LEVEL OF EVIDENCE

Level II, retrospective study.

Associated patellofemoral osteoarthritis is not a contraindication for unicompartmental knee replacement. Report of one hundred ten prostheses with an average 6-year follow-up

INTRODUCTION

Associated patellofemoral joint osteoarthritis (APFJ-OA) has typically been considered a contraindication for unicompartmental knee arthroplasty (UKA) in the treatment of femorotibial joint osteoarthritis. However, this contraindication is being challenged. The aim of this study was to assess clinical and functional outcomes, complications, and implant survival in medial or lateral UKA, regardless of clinical symptoms or radiographic signs of APFJ-OA.

METHODS

This retrospective, comparative study included patients treated with medial or lateral UKA regardless of preoperative symptoms or signs of APFJ-OA, with a minimum 2-year follow-up. Intraoperatively, knees were subdivided based on APFJ-OA grade, according to the Outerbridge classification. Clinical and functional outcomes were analyzed using the 2011 Knee Society Score (KSS) at the last follow-up control. APFJ-OA was treated systematically, in a tailored, stepwise fashion according to its severity. Complications and implant survival rates were evaluated. Two-sided paired T-test, ANOVA, and Kruskal-Wallis tests were used with a significance level of 5%.

RESULTS

Finally, 110 UKAs were assessed 81 (73.6%) medial and 29 (26.4%) laterals. The average follow-up was 6 years (2-19.5). According to Outerbridge, 22 knees (20%) were in grade 2, 59 (53.6%) were in grade 3, and 29 (26.4%) were in grade 4. All three groups showed a statistically significant increase in KSS scores and range of motion. There were no significant differences in clinical KSS improvement and flexion contracture between Outerbridge groups (average 35.7 and -4.9, respectively). Group 3 showed statistically significant improvement in functional KSS when compared to group 2 (68.8 vs 61.2). In maximum flexion, groups 3 and 4 did significantly better than group 2 (20° vs 15°). Three prostheses (2.7%) needed revision after 7, 8.6, and 12 years due to aseptic tibial loosening. Implant survival was 100% at 5 (64 of 64), 97% at 7 (30 of 31), 93% at 9 (14 of 15), and 89% at 12 years, respectively (8 of 9).

CONCLUSION

Clinical and functional results, complications, and survival of medial or lateral UKA were not negatively affected by APFJ-OA assessed intraoperatively using the Outerbridge classification after an average follow-up of 6 years. We consider that APFJ-OA is not a contraindication for UKA when treated systematically according to its severity.

LEVEL OF EVIDENCE

IV.

The influence of varus and valgus deviation on the contact area of patellofemoral joint in healthy knees

OBJECT

Varus-valgus lower alignment is a risk factor for patellofemoral osteoarthritis, but malalignment alone affect not only the tibiofemoral joint but also the patellofemoral joint. The aim of the present study was to analyse the contact area of patellofemoral joint in varus alignment and valgus alignment of healthy subjects using magnetic resonance imaging.

METHODS

Twenty-six healthy subjects with valgus lower limb alignment (Group I, n = 26) and twenty-six volunteers with varus lower limb alignment (Group II, n = 26) was performed. An MRI scan was used to capture and measure the patellofemoral joint articular cartilage contact area at different degrees of knee flexion (20°, 40°,60°) in passive movement. All subjects were categorized on the basis of the global limb alignment and mechanical alignment of the femur and tibia. Varus alignment is hip-knee-ankle angle ≥ 3°; and valgus alignment is hip-knee-ankle angle ≥ - 3°. To obtain medial facet contact area and lateral facet contact area for each slice, the length of each respective line of contact was multiplied by the 5 mm slice thickness.

RESULTS

The overall joint contact area increased from 168.0 ± 20.5 mm2 at 20° knee flexion to 334.4 ± 30.5 mm2 at 60° knee flexion in group (I) The overall joint contact area increased from 178.0 ± 18.9 mm2 at 20° knee flexion to 328.9 ± 27.2 mm2 at 60° knee flexion in group (II) There was a significant difference in lateral facet contact area between group I and group II at 40° of knee flexion. There was significantly different in medial facet contact area between group I and group II at 20° and 40° of knee flexion.

CONCLUSIONS

Throughout the knee movement, the contact area on the lateral facet of the patellofemoral joint was greater in the valgus group. In the early phase of knee flexion, the contact area of the medial patellofemoral joint was larger in the varus group. Lower alignment is an important factor in patellofemoral joint degeneration.

Study on the correlation between the severity of patellofemoral arthritis and the morphology of the distal femur

PURPOSE

Distal femoral torsion is a key factor for poor alignment of patellofemoral joint. This study aims to evaluate the correlation between distal femoral torsion and the severity of patellofemoral arthritis, and to analyze the correlation between distal femoral torsion and the morphology of femoral condyle.

METHODS

A retrospective analysis was performed on 125 patients awaiting surgical treatment for knee osteoarthritis from January 2021 to March 2022(79 females, 46 males, average age: 65.78 years, SD 6.61). All patients underwent knee joint radiography, lower-limb digital radiography, and knee joint CT scans. The ratio of length of each distal femoral condyle, TT-TG, patellar tilt, DFL-PCL, DFL-TEA, TEA-PCL and TEA-ACL were measured. The Pearson correlation coefficient was used to evaluate the correlation between distal femoral torsion and ratio of distal femoral condyle, TT-TG and patellar tilt. Logistic regression was used to evaluate the correlation between each parameter and the severity of PFOA.

RESULTS

With the increased severity of PFOA, TT-TG, patellar tilt, DFL-PCL, DFL-TEA and PCA all tended to increase. Patellar tilt was correlated with DFL-PCL (r = 0.243) and TEA-PCL(r = 0.201), but TT-TG had no evident correlation with distal femoral torsion. Compared with Grade I patients of PFOA, DFL-PCL, DFL-TEA, and TEA-PCL were risk factors for increased severity of patellofemoral arthritis in Grade III patients of PFOA, but there was no significant statistic difference in Grade II patients of PFOA.

CONCLUSIONS

Distal femoral torsion correlates with the severity of patellofemoral arthritis. Variation of the femoral transepicondylar axis caused by the change of ratio of the femoral condyle is particularly important in the distal femoral torsion. In patients with severe PFOA, abnormal variation of the femoral condyle axis should be not ignored.

Femoral morphology affects postoperative alignment of the lower extremities in hybrid closed-wedge high tibial osteotomy

INTRODUCTION

This study aimed to determine correction error predictors of lower extremitiy alignment after hybrid closed-wedge high tibial osteotomy (HCWHTO).

MATERIALS AND METHODS

From 2011 to 2015, 102 knees in 75 patients with medial compartment knee osteoarthritis of the knee and varus knee deformities who underwent HCWHTO were evaluated in this retrospective study with a minimum 2-year follow-up. Preoperative radiological parameters including weight-bearing line ratio (WBL ratio), mechanical leg axis angle, mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), and JLCA under varus or valgus stress were measured. The knees were divided into the following three groups based on the WBL ratio on average 54 months after procedure: acceptable (WBL crossing the tibial plateau between 50 and 70%), under-correction (< 50%), and overcorrection (> 70%). A multiple regression analysis was performed to evaluate predictors that could influence postoperative WBL ratio and cut-off values of predictive preoperative factors was analysed.

RESULTS

Significant differences in pre- and postoperative WBL ratios and mechanical leg axis angles were found. Preoperative mLDFA in the under-correction group (89.4° ± 2.1°) was significantly higher than that in the overcorrection group (87.4° ± 2.2°) (p = 0.015), while other preoperative parameters revealed no significant differences. The postoperative MPTA in the under-correction group (92.1° ± 3.7°) was significantly lower than that in the other two groups (p = 0.005 and p = 0.0001, respectively), while there was no significant change between the acceptable (94.6° ± 3.4°) and the overcorrection (96.7° ± 3.2°) groups. Multiple regression analysis revealed that mLDFA (β =  - 0.316; p = 0.010) had a significant impact on postoperative WBLR. The cut-off value for under-correction of mLDFA was 89.5°and sensitivity and specificity were 53.6 and 71.6%, respectively (p = 0.014).

CONCLUSIONS

Preoperative mLDFA is significantly associated with postoperative alignment in HCWHTO. While postoperative MPTA is important, disregarding the preoperative mLDFA may bears a high risk of malcorrection. Varus alignment of the knee with larger mLDFA may be an indication for not only HCWHTO, but also for distal femoral osteotomy.

Tibial tubercle-Roman arch (TT-RA) distance is superior to tibial tubercle-trochlear groove (TT-TG) distance when evaluating coronal malalignment in patients with knee osteoarthritis

OBJECTIVES

To verify tibial tubercle-Roman arch (TT-RA) distance is superior to tibial tubercle-trochlear groove (TT-TG) distance in preoperative assessment of patellofemoral joints in patients with knee osteoarthritis.

METHODS

Patients with knee osteoarthritis from 2016 to 2020 were considered eligible for inclusion in this study. We divided the patients into valgus group and varus group and did 1:1 matching for the two groups. We measured the TT-TG distance, TT-RA distance, patellar height, patella tilt, hip-knee-ankle (HKA) angle, and Iwano's classification of patellofemoral osteoarthritis (PFOA) by computed tomography images or radiographs. The intraclass correlation coefficient (ICC) of each measurement, the correlations and differences among the parameters, and binary logistic regression analysis were conducted.

RESULTS

Each group in this study included 75 knees. The inter-observer and intra-observer reliability of the TT-TG distance decreased with the increasing degree of PFOA (ICC < 0.75). The reliability of the TT-RA distance showed excellent agreement in different stages of Iwano's classification. The HKA angle was poorly correlated with the TT-TG distance (r = 0.34, p = 0.003) and the TT-RA distance (r = 0.39, p = 0.001) in valgus knees. As the HKA angle increased by 1 degree, the TT-TG and TT-RA distance increased by nearly 0.45 mm and 0.61 mm, respectively. Valgus malalignment and severe PFOA revealed significant ORs of 3.26 (95% CI [1.06-10.03], p = 0.036) and 3.10 (95% CI [1.01-9.54], p = 0.048) with regard to pathological TT-RA distance, respectively.

CONCLUSION

The TT-RA distance was more reliable than the TT-TG distance in patients with knee osteoarthritis. Valgus malalignment and severe PFOA were risk factors for pathological TT-RA distance.

KEY POINTS

• The TT-RA distance is a reliable and repeatable alternative to the TT-TG distance in evaluating coronal malalignment, especially in patients with severe PFOA. • We validated the significant relationships between TT-TG distance or TT-RA distance and HKA angle in valgus knees, while the correlations among such parameters were not significant in varus knees. • Pathological lateralization of the tibial tubercle was prone to be traced in patients with valgus malalignment or severe PFOA, which could contribute to the patellofemoral malalignment.

Quadriceps muscle volume has no effect on patellofemoral cartilage lesions in patients with end-stage knee osteoarthritis

PURPOSE

The quadriceps muscle has a positive effect on anterior knee pain. However, its effect on the patellofemoral (PF) cartilage in patients with end-stage knee osteoarthritis is unknown. The present study aimed to evaluate whether the quadriceps muscle area had a positive effect on the PF cartilage and whether this muscle had a positive effect on the clinical scores.

MATERIALS AND METHODS

Patients with confirmed cartilage status and clinical scores who underwent total knee arthroplasty (TKA) were included. The PF cartilage status was evaluated during TKA. The thickness and the area of the quadriceps muscle were measured using a knee computed tomography scan obtained before the surgery. The Q-angle, hip-knee-ankle angle, alignment, and Insall-Salvati ratio were measured by radiography.

RESULTS

Altogether, 204 patients were included in the study. Logistic regression was performed including factors associated with PF cartilage lesions. The regression model was found to be statistically significant (Hosmer-Lemeshow test, χ² = 0.493). A smaller hip-knee-ankle (HKA) angle was associated with a higher incidence of PF cartilage lesions (p = 0.033) and only the alignment had an effect on the PF cartilage lesions. PF cartilage lesions did not correlate with the clinical scores. A thicker medial portion of the quadriceps muscle was associated with a significantly higher Knee Society Knee Score (KSKS) (p = 0.028).

CONCLUSIONS

Quadriceps muscle thickness and area, Q-angle, and patellar height were not associated with PF cartilage lesions, while a smaller HKA angle was associated with PF cartilage lesions. The presence of PF cartilage lesions did not affect the clinical symptoms. However, a thicker medial portion of the quadriceps muscle was associated with a higher KSKS.

Medial Open Wedge High tibial Osteotomy (MOWHTO) does not relevantly alter patellar kinematics: a cadaveric study

PURPOSE

The purpose of this study was to quantify the influence of medial open wedge high tibial osteotomy on patellar kinematics using optical computer navigation, as anterior knee pain infrequently occurs postoperatively and the reason is still being unknown.

METHODS

Ten medial open wedge high tibial osteotomies at supratuberosity level in 5 full body specimens were performed. The effect of the surgical procedure on patellar kinematics, measured at 5 and 10 degrees of leg alignment correction angle, was analyzed and compared to native patellar kinematics during passive motion-regarding patella shift, tilt, epicondylar distance and rotation. Linear mixed models were used for statistical analysis, a two-sided p value of ≤ 0.05 was considered statistically significant.

RESULTS

Tilt behavior, medial shift and epicondylar distance did not show a significant difference regarding natural patellar kinematics at both osteotomy levels. Both osteotomy correction angles showed a significant less external rotation of the patella (p < 0.001, respectively) compared to natural kinematics.

CONCLUSIONS

Except less external rotation of the patella, medial open wedge high tibial osteotomy does not seem to relevantly alter patellar alignment during passive motion. Future clinical studies have to prove the effect of MOWHTO on patellar kinematics measured in this experimental setup, especially regarding its influence on anterior knee pain.

Does arthroscopic patellar denervation with high tibial osteotomy improve anterior knee pain?

PURPOSE

Patellofemoral (PF) joint osteoarthritis (OA) is a major cause of anterior knee pain. Combined PF and medial tibiofemoral (TF) OA is common in older adults. We evaluated the effect of arthroscopic patellar denervation (PD) in patients with combined TF and PFOA after malalignment correction.

METHODS

Forty-five patients [females/males, 27/18; age, 30-59 years (45.5 ± 8.50); mean body mass index, 25.15 ± 3.04 kg/m²] were treated in our department from March 2017 to March 2019. The patients were randomised into 2 groups: group A included 22 patients who underwent open-wedge high tibial osteotomy (OWHTO) and arthroscopic PD and group B included 23 patients who underwent OWHTO without denervation. The effect of denervation was statistically and clinically evaluated using the Knee injury and Osteoarthritis Outcome Score (KOOS) and Kujala (anterior knee pain score) score.

RESULTS

After 24 months, 40 patients were available for the final follow-up. The final values of KOOS and the Kujala score were significantly different between the groups (p < 0.001). For group A, the average KOOS improved from 42.73 to 72.38 (p < 0.001) and the Kujala score improved from 42 to 74.1 (p < 0.001), whereas in group B, the average KOOS improved from 39.22 to 56.84 (p < 0.001) and the Kujala score improved from 39.7 to 56.4 (p < 0.001).

CONCLUSION

Adding arthroscopic PD to OWHTO relieves anterior knee pain in patients with combined TF and PFOA and improves knee joint function and quality of life.

LEVEL OF EVIDENCE

Level I prospective randomised control clinical trial.

Varus Knee Deformity Classification Based on Degree and Extra- or Intra-Articular Location of Coronal Deformity and Osteoarthritis Grade

BACKGROUND

Medial coronal plane malalignment, also known as varus alignment, is commonly reported in osteoarthritic knees. Although the degree of deformity provides some insight regarding the severity of the disease, it does not always reflect the potential complexity of the surgical treatment.

METHODS

This prospective observational study was conducted by analyzing the radiographs of 100 consecutive knees in patients undergoing total knee arthroplasty. For each knee, coronal alignment, expressed as the hip-knee-ankle angle, was measured on a full-leg standing radiograph and classified in 3 stages. The primary location of the varus deformity was identified as intra-articular and/or extra-articular. Additionally, knees were evaluated to assess for 10 radiographic features of varus deformity and then classified in 3 grades of osteoarthritis severity.

RESULTS

The mean (and standard deviation) preoperative varus deformity was 11° ± 6° of varus (hip-knee-ankle, 169°), as measured on standardized full-leg radiographs. Extra-articular varus deformity was observed in 14% of patients. A higher number of radiographic features of varus severity corresponded with higher degrees of deformity. Varus grade correlated strongly with stage of varus deformity. Twenty-three (100%) of 23 stage-III deformities had grade-C features; however, 13 (48%) of 27 stage-I patients also had grade-C disease.

CONCLUSIONS

One of every 7 osteoarthritis patients with varus deformity had an extra-articular deformity, and 1 of 2 of these patients had severe intra-articular disease (grade C) despite limited coronal deformity (stage I). These findings reconfirm the need for individual deformity analysis that accounts for the degree, location, and severity of the varus deformity. This insight may help to formulate an algorithmic treatment approach specific to the epiphyseal knee anatomy of the patient and according to the surgical preferences of the surgeon.

CLINICAL RELEVANCE

Knee surgeons tend to consider knees with higher degrees of coronal deformity as more technically difficult, but the present study shows that knees with less deformity can still present with severe grades of osteoarthritis inside the knee, leading to more challenging joint reconstruction.

Intraoperative repair for iatrogenic MCL tear due to medial pie-crusting in TKA yields satisfactory mid-term outcomes

PURPOSE

This study aimed to assess the rate of iatrogenic mid-substance superficial medial collateral ligament (sMCL) tear due to the medial pie-crusting technique during varus deformity total knee arthroplasty and compare the knee society score (KSS), range of motion (ROM), and instability rate of the repaired group to the control group with intact sMCL.

METHODS

For this retrospective series of prospectively collected data, the multiple needle puncturing technique was performed for 653 out of the 1768 knees during algorithmic medial soft-tissue release. Iatrogenic tear was observed in 35 knees (5%); hence, repair with running locking nonabsorbable braided suture was performed. Patients were visited and reviewed both clinically and radiographically at 6 weeks, 3 months, 6 months, 12 months, and annually thereafter. Chi-square, ANOVA, Mann-Whitney, independent and paired t test were used to analyze the variables. P value < 0.05 was considered statistically significant.

RESULTS

85% of the repaired sMCL had stable joints with a mean KSS of 88 ± 3 and a mean ROM of 103 ± 11 degrees (°). The other five patients (15%) with mean KSS of 40 ± 8 and mean ROM of 81° ± 5° had an instability and needed to undergo a revision surgery. The control group had a mean KSS of 86 ± 15 and mean ROM of 107° ± 8°; however, 7 knees had an instability and needed a revision surgery. No significant difference was observed in terms of KSS (P = 0.86) and ROM (P = 0.64) between the control and repaired groups.

CONCLUSION

The mid-substance sMCL tear is an important intraoperative complication of medial pie-crusting. Repairing this iatrogenic tear with nonabsorbable suture had satisfying clinical outcomes regarding the postoperative knee ROM and KSS in comparison to the control group. However, there is a chance of failure, which should be perceived by the surgeons.

LEVEL OF EVIDENCE

Therapeutic studies, investigating the results of treatment, Level III.

A quantitative MRI investigation of the association between iliotibial band syndrome and patellofemoral malalignment

Background

The iliotibial band (ITB) has a wide patellar insertion that provides lateral restraint to the patella and maintains the patellofemoral joint's stability. There has been limited investigation into the relationship between patellofemoral malalignment and iliotibial band syndrome (ITBS).

Methods

We retrospectively analyzed 47 knees with ITBS by retrieving magnetic resonance imaging (MRI) data collected over an approximately 6-year period from our database. The Insall-Salvati ratio, lateral patellofemoral angle (LPA), lateral patellar tilt (LPT), lateral trochlear length (LTL), angle of the non-weight-bearing facet of the lateral femoral condyle (nwb-LFCA), and the ITB-lateral femoral condyle (IT-LFC) distance were measured on MR images. The knees of 47 age- and gender-matched subjects were enrolled as the normal group.

Results

In the ITBS group, over one third (34%, 16/47) of knees had abnormal patellofemoral measurements, including 8 (17%, 8/47) knees with patellar alta, 11 (23.4%, 11/47) knees with an abnormally decreased LPA, and 5 (10.6%, 5/47) knees with an abnormally increased LPT indicating lateral patellar tilt. Moreover, 8 knees had simultaneous combinations of two or three abnormality parameters, and 8 (17%, 8/47) knees presented with superolateral Hoffa's fat pad edema. The Insall-Salvati ratio, LPT, and nwb-LFCA in the ITBS group were significantly higher than those in the normal group (P=0.001, P<0.001, and P<0.001, respectively); the LPA and IT-LFC distances in the ITBS group were significantly lower (P=0.003, P<0.001, respectively) than those in the normal group. There were mild to moderate correlations between the MRI parameters and ITBS (P=0.006, P<0.001, respectively).

Conclusions

This study confirmed that a higher position or lateral tilt of the patella and a steeper morphology of the anterior part of the lateral femoral condyle were associated with the development of ITBS, which is helpful in understanding and further exploring the mechanism of ITBS.

Medialization of the mechanical axis of the tibia is related to lateralization of the tibial tuberosity in knee osteoarthritis

PURPOSE

To determine whether medialization of the proximal tibia due to a varus deformity is related to lateralization of the tibial tuberosity in varus knee osteoarthritis (OA).

METHODS

A total of 120 knees that underwent osteotomies around the knee for varus knee OA were enrolled. Mechanical medial proximal tibial angle (mMPTA) was measured on radiographs. The angle between the mechanical and anatomical axes of the tibia (angle MA) and the distance between the centre of the tibial plateau and the anatomical axis (distance MA) were measured in the coronal plane on computed tomography images. The tibial tuberosity-posterior cruciate ligament (TT-PCL) distance, the distance between the midpoint of the tibial tuberosity and the centre of the tibial plateau (TT-centre distance), and the angle between the line through the midpoint of the tibial tuberosity and the centre of the tibial plateau and the anteroposterior axis (TT-centre angle) were measured in the axial plane. The correlations of these parameters were evaluated.

RESULTS

mMPTA correlated negatively with angle MA (r = -0.37, P < 0.01) and distance MA (r = -0.55, P < 0.01). Angle MA and distance MA correlated with TT-PCL distance (r = 0.39, P < 0.01, r = 0.42, P < 0.01), TT-centre distance (r = 0.35, P < 0.01, r = 0.38, P < 0.01) and TT-centre angle (r = 0.36, P < 0.01, r = 0.36, P < 0.01).

CONCLUSIONS

Medialization of the proximal tibia due to a varus deformity may induce lateralization of the tibial tuberosity.

Varus inclination of the tibia is related to patellofemoral osteoarthritis in Japanese female patients with moderate knee osteoarthritis

PURPOSE

The aim of this study was to investigate whether the tibial tuberosity-trochlear groove (TT-TG) distance and lateral patellar tilt, which induce patellofemoral osteoarthritis (OA), are related to the coronal deformity of the lower limb in varus knee OA. It was hypothesized that varus inclination of the tibia was negatively correlated with the TT-TG distance and lateral patellar tilt in Japanese female patients with moderate knee OA.

METHODS

A total of 104 female patients (139 knees) scheduled to undergo knee osteotomy for varus knee OA were enrolled. The coronal lower limb alignment was measured on anteroposterior whole-leg radiographs. The TT-TG distance, patellar tilt angle, and the patellofemoral joint space were measured both medially and laterally on computed tomography images. The correlations between coronal lower limb alignment and the TT-TG distance or patellar tilt angle, and the correlations between the TT-TG distance or patellar tilt angle and patellofemoral joint space were evaluated.

RESULTS

The medial proximal tibial angle was negatively correlated with the TT-TG distance (r =  - 0.383, P < 0.01) and patellar tilt angle (r =  - 0.34, P < 0.01). Lateral patellofemoral joint space was negatively correlated with the TT-TG distance (r =  - 0.256, P = 0.002) and patellar tilt angle (r =  - 0.205, P = 0.016).

CONCLUSIONS

Varus inclination of the proximal tibia may induce lateralization of the tibial tuberosity and lateral patellar tilt. The tibial tuberosity lateralization and lateral patellar tilt may induce lateral patellofemoral OA in patients with varus knee OA.

LEVEL OF EVIDENCE

III.

Association of subchondral bone marrow lesion localization with weight-bearing pain in people with knee osteoarthritis: data from the Osteoarthritis Initiative

Background

Subchondral bone marrow lesions (BMLs) detected on MRI in knee osteoarthritis (OA) are associated with knee pain. The prevalence and progression of subchondral BMLs are increased by mechanical knee load. However, associations of subchondral BML location with weight-bearing knee pain are currently unknown. In this study, we aim to demonstrate associations of subchondral BML location and size with weight-bearing knee pain in knee OA.

Methods

We analyzed 1412 and 582 varus knees from cross-sectional and longitudinal Osteoarthritis Initiative datasets, respectively. BML scores were semi-quantitatively analyzed with the MRI Osteoarthritis Knee Score for 4 subchondral regions (median and lateral femorotibial, medial and lateral patellofemoral) and subspinous region. Weight-bearing and non-weight-bearing pain scores were derived from WOMAC pain items. Correlation and negative binomial regression models were used for analysis of associations between the BML scores and pain at baseline and changes in the BML scores and changes in pain after 24-month follow-up.

Results

Greater BML scores at medial femorotibial and lateral patellofemoral compartments were associated with greater weight-bearing pain scores, and statistical significance was retained after adjusting for BML scores at the other 4 joint compartments and other OA features, as well as for non-weight-bearing pain, age, sex, and body mass index (BMI) (medial femorotibial; B = 0.08, p = 0.02. patellofemoral; B = 0.13, p = 0.01). Subanalysis revealed that greater medial femorotibial BML scores were associated with greater pain on walking and standing (B = 0.11, p = 0.01, and B = 0.10, p = 0.04, respectively). Lateral patellofemoral BML scores were associated with pain on climbing, respectively (B = 0.14, p = 0.02). Increases or decreases over 24 months in BML score in the medial femorotibial compartment were significantly associated with increases or decreases in weight-bearing pain severity after adjusting for non-weight-bearing pain, age, sex, baseline weight-bearing pain, BMI, and BML at the other 4 joint compartments (B = 0.10, p = 0.01).

Conclusions

Subchondral BML size at the medial femorotibial joint compartment was specifically associated with the severity and the change in weight-bearing pain, independent of non-weight-bearing pain, in knee OA. Specific associations of weight-bearing pain with subchondral BMLs in weight-bearing compartments of the knee indicate that BMLs in subchondral bone contribute to biomechanically induced OA pain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02422-0.

Preoperative flexion contracture is a predisposing factor for cartilage degeneration at the patellofemoral joint after open wedge high tibial osteotomy

Purpose

The purpose of the study was to determine the effect of cartilage degeneration at the patellofemoral joint on clinical outcomes after open wedge high tibial osteotomy and to investigate the predisposing factors for progressive patellofemoral cartilage degeneration.

Methods

Seventy-two knees were evaluated on second-look arthroscopy in patients who opted for plate and screw removal at an average of 20.1 months after osteotomy. Cartilage degeneration at the patellofemoral joint was evaluated using the International Cartilage Repair Society grading system, with cases divided into progression and nonprogression groups. Radiographic parameters of the patellofemoral anatomy, knee range of motion, and clinical outcomes were evaluated from the preoperative baseline to the final follow up, on average 50 months after osteotomy. A contracture > 5° was considered a flexion contracture.

Results

Cartilage degeneration progressed in 31 knees, and preoperative knee flexion contracture was significantly associated with progressive degeneration (P < 0.01). The Lysholm and Kujala scores were significantly lower in the progression group (87.9 and 85.3, respectively) than in the nonprogression group (91.6 and 93.6, respectively) (P < 0.05). The odds ratio of the flexion contracture resulting in progression of patellofemoral cartilage degeneration was 4.63 (95% confidence interval, 1.77–12.1). No association was detected between progressive degeneration and age, sex, body mass index, Kellgren-Lawrence grade, or radiographic parameters.

Conclusions

Flexion contracture may be associated with progression of cartilage degeneration at the patellofemoral joint and may negatively affect the clinical outcomes after open wedge, high tibial osteotomy.

Tibial tuberosity-tibial intercondylar midpoint distance measured on computed tomography scanner is not biased during knee rotation and could be clinically more relevant than current measurement systems

PURPOSE

The purpose of this retrospective cross-sectional case-control study was to evaluate an alternative imaging test for lateralization of the tibial tuberosity, unbiased towards knee rotation.

METHODS

On axial CT images of 129 knees, classified as cases (two or more patellar luxations) and controls (no patellar luxations), two raters gauged the standard tibial tuberosity-trochlear groove (TT-TG) distance, tibial tuberosity-femoral intercondylar midpoint (TT-FIM) distance, and new tibial tuberosity-tibial intercondylar midpoint (TT-TIM) distance singly, and knee longitudinal rotation angles (LRAs), and the presence of femoral trochlear dysplasia (FTD) jointly.

RESULTS

All imaging tests intercorrelated and discriminated between stability groups. TT-TIM had the lowest values with the highest precision. Though poorly, TT-TG and TT-FIM negatively correlated with age and LRAs regarding femur, but positively with presence of FTD, whereas TT-TIM was unbiased. The accuracy of TT-TG (> 20 mm), TT-FIM (> 20 mm), and TT-TIM (> 13 mm) was good with almost perfect reproducibility. Only TT-TIM was sex-biased (p = 0.009), with > 12 mm cut-off in females and (presumably) > 14 mm in males.

CONCLUSION

TT-TIM is an alternative imaging test for lateralization of the tibial tuberosity, unbiased towards knee rotation.

Criterion validity of ultrasound in the identification of calcium pyrophosphate crystal deposits at the knee: an OMERACT ultrasound study

OBJECTIVE

To evaluate the discriminatory ability of ultrasound in calcium pyrophosphate deposition disease (CPPD), using microscopic analysis of menisci and knee hyaline cartilage (HC) as reference standard.

METHODS

Consecutive patients scheduled for knee replacement surgery, due to osteoarthritis (OA), were enrolled. Each patient underwent ultrasound examination of the menisci and HC of the knee, scoring each site for presence/absence of CPPD. Ultrasound signs of inflammation (effusion, synovial proliferation and power Doppler) were assessed semiquantitatively (0-3). The menisci and condyles, retrieved during surgery, were examined microscopically by optical light microscopy and by compensated polarised microscopy. CPPs were scored as present/absent in six different samples from the surface and from the internal part of menisci and cartilage. Ultrasound and microscopic analysis were performed by different operators, blinded to each other's findings.

RESULTS

11 researchers from seven countries participated in the study. Of 101 enrolled patients, 68 were included in the analysis. In 38 patients, the surgical specimens were insufficient. The overall diagnostic accuracy of ultrasound for CPPD was of 75%-sensitivity of 91% (range 71%-87% in single sites) and specificity of 59% (range 68%-92%). The best sensitivity and specificity were obtained by assessing in combination by ultrasound the medial meniscus and the medial condyle HC (88% and 76%, respectively). No differences were found between patients with and without CPPD regarding ultrasound signs of inflammation.

CONCLUSION

Ultrasound demonstrated to be an accurate tool for discriminating CPPD. No differences were found between patents with OA alone and CPPD plus OA regarding inflammation.

Correlation of T2* relaxation times of the retropatellar cartilage with tibial tuberosity-trochlea groove distance in professional soccer players

The tibial tuberosity–trochlear groove (TT–TG) distance is a radiographic measurement that is used to quantify malalignment of the patellofemoral joint (PFJ) in cross-sectional imaging. There is an ongoing debate about the impact of the TT–TG-distance on lateral patellar instability and the initiating of cartilage degeneration. In this prospective study, the association of T2* relaxation times and TT–TG distances in professional soccer players was analyzed. 36 knees of 18 professional soccer players (age: 21 ± 2.8 years) were evaluated. Participants underwent knee MRI at 3 T. For qualitative image analysis, fat-saturated 2D PD-weighted Fast Spin Echo (FSE) and T1-weighted FSE sequences were used. For quantitative analysis, T2* measurements in 3D data acquisitions were performed. In a qualitative analysis there was no structural cartilage damage and no abnormalities of the patellar and trochlea shape. The highest T2* values (26.7 ± 5.9 ms) were observed in the central compartment of the patella. The mean TT–TG distance was 10 ± 4 mm (range 3–20 mm). There was no significant correlation between TT–TG distance and T2* relaxation times in all three compartments of the retropatellar cartilage. Our study shows that so long as patellar and trochlear morphology is normal, TT–TG distance alone does not affect the tissue structure of the retropatellar cartilage in professional soccer players.

Changes in patellar height and patellofemoral alignment following double level osteotomy performed for osteoarthritic knees with severe varus deformity

Purpose

To evaluate the effect of double level osteotomy (DLO), a combination of a lateral closed distal femoral osteotomy (LCWDFO) and medial opening wedge high tibial osteotomy (MOWHTO), on patellar height and patellofemoral alignment as compared to those of isolated MOWHTO.

Methods

Twenty-six consecutive knees in 26 patients who underwent DLO (DLO group) constituted the study population. For comparative purpose, a control cohort (N: 26) matched for age, sex, and body mass index with the study group were selected from the patients who underwent isolated MOWHTO with an opening gap of more than 10 mm during the same period (MOWHTO group). Patellar height and patellofemoral alignment were assessed on radiographs preoperatively and at 2 years after surgery. For the patellar height, following parameters were measured on a lateral radiograph: Modified Insall-Salvati Index (mISI), modified Caton–Deschamps Index (mCDI), and modified Blackburne-Peel Index (mBPI). In the assessment of patellofemoral alignment, lateral patellar tilt (LPT) and lateral patellar shift (LPS) were measured on a skyline view. The measured values were statistically compared using the Student’s t-test.

Results

In the DLO group, the patellar height measured by mCDI and mPBPI significantly decreased after surgery. As regards the patellofemoral alignment, LPT significantly decreased with no significant postoperative change detected for LPS. When the amounts of postoperative changes in radiological indices were compared between the DLO and isolated MOWHTO groups, no significant differences were detected for all parameters.

Conclusion

DLO induced reduction in patellar height and decreased lateral patellar tilt. Those changes in patellar position and orientation were similarly observed in isolated MOWHTO knees. Although DLO is specifically indicated for knees with severe varus deformity, the two surgical options for correction of varus knee deformity exerted similar influences on patellofemoral biomechanics.

Patellar Malalignment Is Associated With Patellofemoral Lesions and Cartilage Relaxation Times After Hamstring Autograft Anterior Cruciate Ligament Reconstruction

BACKGROUND

There is growing evidence suggesting a link between patellofemoral joint (PFJ) osteoarthritis in anterior cruciate ligament (ACL)-reconstructed knees and altered joint alignment.

PURPOSE

To determine whether patellar alignment differs between participants with and without ACL reconstruction (ACLR) and to identify possible associations between patellar alignment and PFJ osteoarthritis features over 3 years.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 37 participants with ACLR (sex, 23 male; mean ± SD age, 28.1 ± 7.4 years) and 20 healthy controls (13 male; 30.4 ± 4.8 years) participated. Patients underwent magnetic resonance imaging: (1) sagittal T2-weighted fat-saturated fast spin echo images to calculate patellar alignment, (2) sagittal 3-dimensional intermediate-weighted fast spin echo Cube sequence for clinical morphological grading (modified Whole-Organ Magnetic Resonance Imaging Score [WORMS]), and (3) sagittal combined T_1ρ/T₂ mapping sequence for performing voxel-based relaxometry. Patellar alignment of the ACLR knees were assessed at 6 months (baseline). One-way analysis of variance was used to compare patellar alignment among the ACLR (at 6 months), contralateral, and control knees. Within the ACLR group, a logistic regression model was used to identify if patellar alignment measures at baseline were risk factors for worsening of PFJ structural changes over 3 years. Statistical parametric mapping was used to evaluate the longitudinal associations between patellar alignment and cartilage relaxation times at 3 years.

RESULTS

When compared with control knees, ACLR knees exhibited a laterally and anteriorly displaced patella (P = .045 and P = .041), less flexion (P = .031), and less lateral spin (P = .012). Furthermore, excessive lateral displacement was a significant predictor of worsening of WORMS (P = .050). Lateral displacement was positively correlated with increased T_1ρ and T₂ in the patellar and trochlear cartilage at 3 years. Patellar lateral spin revealed similar negative findings.

CONCLUSION

Participants with ACLR exhibited a laterally and anteriorly displaced patella, less flexion, and less lateral spin when compared with healthy controls. Excessive patellar lateral displacement was the strongest predictor to the development of PFJ osteoarthritis features longitudinally.

Associations of trochlea morphology and patellofemoral alignment with prevalent radiographic patellofemoral osteoarthritis

OBJECTIVE

To investigate the relation of trochlea morphology and patellofemoral alignment to prevalent radiographic patellofemoral osteoarthritis (PFOA).

DESIGN

A within-person knee-matched case-control study was performed. Participants with unilateral radiographic PFOA were selected from the Multicenter Population-based Osteoarthritis Study (MPOA) in three towns in northern China that was approved by Peking University Health Science Center Ethics Committee (2018PHB166-01). Radiographic PFOA, radiographic tibiofemoral OA, sulcus angle, patellofemoral index and patella displacement were assessed using posterio-anterior and skyline views of the knee. We classified sulcus angle, patellofemoral index and patella displacement into quarters and investigated the relation of each of these measures to prevalent radiographic PFOA.

RESULTS

Among 451 participants (mean age: 65.2 years, women: 66.8%) with unilateral radiographic PFOA, a reverse J-shaped relationship was observed between sulcus angle and prevalent radiographic PFOA (P = 0.039 for quadratic term). Both higher patellofemoral index and patella displacement were associated with higher prevalent radiographic PFOA. Adjusted odds ratios (ORs) of prevalent radiographic PFOA in the highest quarter of patellofemoral index and patella displacement were 4.69 and 3.60 (P for trend <0.001), respectively, compared with the lowest quarter of each measurement. A similar relationship was observed between sulcus angle with either prevalent radiographic lateral or medial PFOA. Higher values of patellofemoral index and patella displacement were statistically significantly associated with higher prevalent radiographic lateral (ORs = 5.07 and 4.59, respectively), but not medial PFOA (ORs = 0.58 and 0.76, respectively).

CONCLUSION

Extreme sulcus angles as well as higher values of patellofemoral index and patella displacement were associated with higher prevalent radiographic PFOA.

High prevalence of patellofemoral osteoarthritis in China: a multi-center population-based osteoarthritis study

BACKGROUND

To describe the prevalence and risk factors of patellofemoral osteoarthritis (PFOA) among Chinese residents.

METHODS

A multi-center population-based osteoarthritis study was conducted in 2014. Residents aged ≥ 50 years old were recruited using a cluster sampling method. Subjects completed a home interview and physical examination and had skyline view of radiographs at patellofemoral (PF) joints. Radiographs were read by two trained musculoskeletal researchers, and discordance of a subject's PFOA status between two readers was adjudicated with a third musculoskeletal researcher present. Radiographic OA at PF joint was defined if osteophytes (OST) score was ≥ 2 or if joint space narrowing (JSN) score was ≥ 2 with concurrent grade 1 OST in the PF joint.

RESULTS

Of 3446 subjects (63.0% women) included in this analysis, the prevalence of radiographic PFOA was 23.9% (20.5% men vs. 25.8% women). Prevalence of lateral radiographic OA was higher than medial radiographic OA at PF joint. Grades of both osteophytes and joint space narrowing in the lateral patellofemoral compartment were higher than those in the medial patellofemoral compartment (all P values < 0.001). Women, older age, higher BMI, and fewer years of education were significantly associated with higher prevalence of radiographic PFOA, osteophytes, and joint space narrowing.

CONCLUSION

Prevalence of radiographic PFOA was high among Chinese population. Key Points • The multi-center population-based osteoarthritis study shows the prevalence of radiographic PFOA was high among Chinese population. • Older age, female gender, obesity, and few years of education were associated with a high risk of PFOA. • Prevalence of lateral radiographic OA was higher than medial radiographic OA at PF joint.

Three-dimensional finite-element analysis of aggravating medial meniscus tears on knee osteoarthritis

BACKGROUND

The biomechanical change during the medial meniscus damage in the process of knee osteoarthritis has not been explored. The purpose of this study was to determine the effect of aggravating medial meniscus degenerative tear on the progress of knee osteoarthritis through the finite-element simulation method.

METHODS

The three-dimensional digital model of a total-knee joint was obtained using a combination of magnetic resonance imaging and computed tomography images. Four types of medial meniscus tears were created to represent the aggravating degenerative meniscus lesions. Meniscectomy of each meniscal tear was also utilized in the simulation. The compression and shear stress of bony tissue, cartilage, and meniscus were evaluated, and meniscus extrusion of the healthy knee, postinjured knee, and postmeniscectomy knee were investigated under the posture of balanced standing.

RESULTS

Based on the results of finite-element simulation, the peak shear principal stress, peak compression principal stress, and meniscus extrusion increased gradually as the meniscus tears' region enlarged progressively (from 7.333 MPa to 15.14 MPa on medial femur and from 6 MPa to 20.94 MPa on medial tibia). The higher stress and larger meniscus extrusion displacement in all tests were observed in the flap and complex tears. The oblique tears also had a biomechanical variation of stress and meniscus extrusion in the knee joint, but their level was milder. Both the peak value of the stress and meniscus displacement increased after the meniscectomy.

CONCLUSION

In contrast to the damaged hemijoint, the stress applied on the healthy lateral hemijoint increased. The change of biomechanics was more obvious with the aggravation of meniscus injury. The advanced degenerative damage resulted in increasing stress that was more likely to cause symptomatic clinical manifestation in the knee joint and accelerate the progress of osteoarthritis. Moreover, we found that the meniscus injury caused higher stress concentration on the contralateral side of the joint. We also discovered that the meniscectomy can lead to more serious biomechanical changes, and although this technique can relieve pain over a period of time, it increased the risk of osteoarthritis (OA) occurrence.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

It is clear that the meniscal lesions can cause osteoarthritic knee, but the biomechanical change during the meniscus damage period has not been explored. We have evaluated the variation of stress during the aggravating medial degenerative meniscus tears and the relationship in the process of knee OA through finite-element simulation. This study does favour to obtain a better understanding on the symptoms and pathological changes of OA. It also may provide some potential directions for the prophylaxis and treatment of OA.

Does Preoperative tibial tuberosity: Trochlear groove distance effect on postoperative patellar instability in the patients with knee arthroplasty due to medium-advanced knee osteoarthritis?

Objectives: Determining tibial tubercle-trochlear groove distance range as measured before the operation in the patients to whom total knee prosthesis will be applied due to mid to advanced level of osteoarthritic and seeing the post-operative variations in tibial tubercle-trochlear groove distance and evaluating whether it has any impact on the patellofemoral instability that might develop after the operation. 46 knees planned to be applied total knee prosthesis due to mid-advanced level of osteoarthritic were examined. Methods: In the preoperative and postoperative magnetic resonance images MRI routinely taken, tibial tubercle-trochlear groove distance was measured. Later it was examined whether there was correlation between these preoperative and postoperative tibial tubercle-trochlear groove measurements and the data recorded before operation. Results: Preoperative tibial tubercle-trochlear groove distance was found to be 8.83 ± 3.54, postoperative tibial tubercle-trochlear groovedistance was found to be 8.30 ± 3.89 and preoperative-postoperative tibial tubercle-trochlear groove variation was found to be 0,52 ± 3,64 (p = 0,337). In the patients whose alignment was 10 degrees or less, Pre-Op tibial tubercle-trochlear groove distance was measured as 8.74 ± 3.18 and in the patients whose alignment was more than 10 degrees, it was measured as 8.89 ± 3,83 (p = 0.888). In the patients whose alignment was 10 degrees or less, Post-Op tibial tubercle-trochlear groove distance was measured as 8.00 ± 2.85 and in the patients whose alignment was more than 10 degrees, it was measured as 8.52 ± 4.52 (p = 0.661). In the patients whose alignment was 10 degrees or less, tibial tubercle-trochlear groove distance variation was measured as 0.74 ± 3.25 and in the patients whose alignment was more than 10 degrees, it was measured as 0.37 ± 3.95 (p = 0.741). Coclusion: As a result, although tibial tubercle-trochlear groove distance was observed with a great variation in the osteoarthritic knees at stage 3-4, it was nonetheless measured within normal limits and Post-Op variation was not meaningful. Since this is the first study in the literature on the measurement of tibial tubercle-trochlear groove distance in the total knee prosthesis applications, we hope that it would shed some light on similar studies to be conducted in the future.

Risk of patella baja after opening-wedge high tibial osteotomy

PURPOSE

Medial opening-wedge high tibial osteotomy (OWHTO) induces a lower patellar position, and the subsequent degree of patellar movement may not be predicted preoperatively. The purpose of this study was to clarify the relationship between preoperative and postoperative patellar height based on the correction angle of OWHTO and to create a formula to predict the appearance of patella baja following OWHTO.

MATERIALS AND METHODS

Seventy-five knees with varus knee osteoarthritis treated with OWHTO were included in this study. The Caton-Deschamps index was used to evaluate patellar height preoperatively and postoperatively, and the cut-off value for preoperative parameters was determined by a receiver operating characteristic curve to determine the risk ratio for postoperative patella baja.

RESULTS

The Caton-Deschamps index significantly decreased from 0.93 to 0.77 after OWHTO ( p < 0.01). The OWHTO correction angle negatively correlated with the delta Caton-Deschamps index ( r = -0.44, p < 0.01), and a 1.7% decrease in the Caton-Deschamps index was shown with a 1° correction angle. Receiver operating characteristic curve analysis revealed that a Caton-Deschamps index of 0.8 was the cutoff for OWHTO; knees with a preoperative Caton-Deschamps index of < 0.8 tended to develop patella baja after OWHTO, with a risk ratio of 9.5 (95% confidence interval [4.3-20.7]).

CONCLUSIONS

OWHTO can induce patella baja, and a 1.7% decrease in the Caton-Deschamps index was shown with a 1°-correction angle. A preoperative Caton-Deschamps index < 0.8 should be considered a risk factor for postoperative patella baja.

LEVEL OF EVIDENCE

Retrospective study, Level IV.

Hybrid closed wedge high tibial osteotomy improves patellofemoral joint congruity compared with open wedge high tibial osteotomy

PURPOSE

To evaluate clinical outcomes and radiographic changes in patellofemoral (PF) joint congruity between open wedge high tibial osteotomy (OWHTO) and hybrid closed wedge HTO (HCWHTO).

METHODS

From 2011 to 2013, 36 knees in 31 patients who underwent OWHTO and 21 knees in 17 patients who underwent HCWHTO were evaluated in this retrospective study with a minimum 5-year follow-up. Radiological outcomes including hip-knee-ankle angle (HKA), femoral patellar height index (FPHI), preoperative PF osteoarthritis (OA) grade, medial and lateral joint spaces of the PF joint, and congruence angle were measured. Clinical parameters including the Knee injury and Osteoarthritis Outcome Score (KOOS) and the Oxford Knee Score (OKS) were also evaluated. Preoperative and final follow-up values for each procedure were compared in outcome analyses.

RESULTS

Mean preoperative HKA and the degree of PF-OA were significantly more severe for patients treated with HCWHTO compared with those treated with OWHTO (p = 0.001, p = 0.0001). Mean postoperative FPHI was significantly decreased with proximalization of the patella in HCWHTO (p = 0.01) but showed no significant change in OWHTO (n.s.). Regarding PF joint congruity after HCWHTO, lateral joint space and congruence angle were significantly improved (p = 0.0001, p = 0.005), while medial joint space was not significantly changed (n.s.). After OWHTO, congruence angle showed no significant difference (n.s.), but medial and lateral joint spaces were significantly decreased (p = 0.0001, p = 0.018). There were no significant differences in KOOS and OKS between the groups (n.s., n.s.).

CONCLUSIONS

Although degrees of varus knee and PF-OA were more severe in HCWHTO than those in OWHTO, HCWHTO led to improved PF joint congruity, and its mid-term clinical outcomes were equivalent to those of OWHTO. Therefore, in patients with varus knee combined with PF-OA preoperatively, HCWHTO is a more effective treatment than OWHTO.

LEVEL OF EVIDENCE

Therapeutic level III.

Hybrid high tibial osteotomy is superior to medial opening high tibial osteotomy for the treatment of varus knee with patellofemoral osteoarthritis

PURPOSE

To evaluate patellofemoral congruity after opening wedge high tibial osteotomy (OWHTO) and hybrid HTO.

METHODS

Twenty-four knees with hybrid HTO and 24 with OWHTO were evaluated in this study. The Caton-Deschamps and modified Miura-Kawamura indices were used to evaluate pre- and post-operative patellar heights for both types of surgery. Tibial tuberosity-trochlear groove (TT-TG) distance, patellar tilt, and medial and lateral joint space at the patellofemoral joint were compared. Anterior knee pain was assessed using the Kujala anterior knee pain scale.

RESULTS

There was no significant difference between the correction angles of the hybrid HTO and OWHTO. Pre- and post-operative values for the Caton-Deschamps and modified Miura-Kawamura indices in patients who underwent hybrid HTO changed from 0.90 to 0.94 and from 0.95 to 1.03, respectively, with no significant differences noted. Following OWHTO, these values decreased significantly from 0.91 to 0.73 and from 1.06 to 0.84, respectively (p < 0.01). The post-operative patellar height after OWHTO was significantly lower than that after hybrid HTO (p < 0.01). After hybrid HTO, the TT-TG distance decreased significantly from 11.4 to 7.4 (p < 0.01), but it did not change significantly after OWHTO. Although pre- and post-operative patellar tilt were not altered significantly in either group, the medial joint space of the patellofemoral joint was significantly increased post-operatively following hybrid HTO (p = 0.035). The pre-operative Kujala scores were significantly lower in the hybrid HTO group, but post-operative scores improved in both groups.

CONCLUSIONS

Hybrid HTO provides a better post-operative patellofemoral joint than does OWHTO with regard to patellar position and reduction of the TT-TG distance, as well as improved clinical outcomes. Hybrid HTO, rather than OWHTO, is the preferred technique for the treatment of varus knees combined with patellofemoral osteoarthritis.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

The association of frontal plane alignment to MRI-defined worsening of patellofemoral osteoarthritis: the MOST study

OBJECTIVE

To determine the sex-specific relation of frontal plane alignment (FPA) to magnetic resonance imaging (MRI)-defined features of patellofemoral osteoarthritis, and also to tibiofemoral osteoarthritis and knee pain.

METHOD

The Multicenter Osteoarthritis Study is cohort study comprised of individuals with or at risk of knee osteoarthritis. We determined the sex-specific dose-response relation of baseline FPA to MRI-defined patellofemoral and tibiofemoral structural worsening, and incident knee pain, over 7 years.

RESULTS

In women only, greater varus alignment was associated with medial patellofemoral osteophytes (risk ratio [RR] 1.7 [95% CI 1.2, 2.6]) and valgus with lateral patellofemoral osteophytes (RR 1.9 [1.0, 3.6]). In men, greater varus increased risk for medial tibiofemoral cartilage worsening (RR 1.7 [1.1, 2.6]), and valgus for lateral tibiofemoral cartilage worsening (RR 1.8 [1.6, 2.2]). In women, findings were similar for tibiofemoral cartilage, but varus also increased risk for medial bone marrow lesions [BMLs] (RR 2.2 [1.6, 3.1]) and medial osteophytes (RR 1.8 [1.3, 2.5]), and valgus for lateral BMLs (RR 3.3 [2.2, 4.5]) and osteophytes (RR 2.0 [1.2, 3.2]). Varus increased risk of incident pain in men (RR 1.7 [1.4, 2.2]) and women (RR 1.3 [1.0, 1.6]), valgus did so in men only (RR 1.5 [1.1, 1.9]).

CONCLUSION

FPA was associated with patellofemoral osteophyte worsening in women, though overall was more strongly associated with tibiofemoral than patellofemoral osteoarthritis feature worsening. FPA in women was more consistently associated with structural worsening, yet men had higher associations with incident pain.

Tibiofemoral kinematics in the transverse and frontal planes influence the location and magnitude of peak patella cartilage stress: An investigation of runners with and without patellofemoral pain

BACKGROUND

To determine whether the location and magnitude of peak patella cartilage stress varies among runners with and without patellofemoral pain. To determine whether tibiofemoral kinematics in the frontal and transverse planes predict peak lateral and medial patella cartilage stress.

METHODS

Twelve recreational runners with patellofemoral pain and 10 pain-free controls participated. Peak patella cartilage stress was quantified using finite element models that incorporated subject-specific kinematic and kinetic data obtained during running. Chi-square analysis was used to determine whether the location of peak patella cartilage stress (medial or lateral) varied between groups. Student's t-tests were used to determine whether the magnitude of peak medial and lateral patella cartilage stress varied between groups. In addition, stepwise regression analysis was performed to determine if tibiofemoral kinematics were predictive of peak medial and lateral cartilage stress.

FINDINGS

Among all subjects, 64% exhibited peak cartilage stress on the lateral patella facet. No group differences were found for the location and magnitude of peak cartilage stress on the medial or lateral facets. Tibiofemoral rotation in the transverse plane was the best predictor of peak lateral stress (45% of the variance, r = 0.67). Tibiofemoral rotation in the transverse plane was the best predictor of peak medial stress (44% of the variance, r = -0.67), followed by tibiofemoral rotation in the frontal plane (26% of the variance, r = 0.57).

INTERPRETATIONS

The location and magnitude of peak patella cartilage stress was similar among runners with and without patellofemoral pain. Tibiofemoral kinematics in the frontal and transverse planes are predictive of cartilage stress on the medial and lateral patella facets.

Omega-3 Polyunsaturated Fatty Acids: Benefits and Endpoints in Sport

The influence of nutrition has the potential to substantially affect physical function and body metabolism. Particular attention has been focused on omega-3 polyunsaturated fatty acids (n-3 PUFAs), which can be found both in terrestrial features and in the marine world. They are responsible for numerous cellular functions, such as signaling, cell membrane fluidity, and structural maintenance. They also regulate the nervous system, blood pressure, hematic clotting, glucose tolerance, and inflammatory processes, which may be useful in all inflammatory conditions. Animal models and cell-based models show that n-3 PUFAs can influence skeletal muscle metabolism. Furthermore, recent human studies demonstrate that they can influence not only the exercise and the metabolic response of skeletal muscle, but also the functional response for a period of exercise training. In addition, their potential anti-inflammatory and antioxidant activity may provide health benefits and performance improvement especially in those who practice physical activity, due to their increased reactive oxygen production. This review highlights the importance of n-3 PUFAs in our diet, which focuses on their potential healthy effects in sport.

Prevalence of excessive lateral pressure syndrome in varus osteoarthritic candidates for high tibial osteotomy

BACKGROUND

This study aimed to determine the prevalence of excessive lateral pressure syndrome (ELPS) in potential candidates for high tibial osteotomy (HTO) using single-photon emission computed tomography-computed tomography (SPECT-CT). We also sought to identify risk factors related to the presence of ELPS.

METHODS

This retrospective study included 150 patients (216 knees) who were candidates for HTO from an initial screening of 3579 patients (7158 knees). There were 183 female and 33 male knees with a mean age of 58 years. The presence of ELPS was defined as a grade 3 uptake on the SPECT-CT at the lateral PF joint. To determine the risk factors related to the ELPS, multivariate regression analysis was performed with independent demographic and radiographic variables.

RESULTS

Increased uptake on the lateral side of the PF joints was detected in 120 knees (56% of total subjects). Of these, 34 (16%) knees presented with a grade 3 uptake, which indicated the presence of ELPS. No single risk factor had significant associations with the presence of ELPS.

CONCLUSIONS

A considerable number of the knees that were candidates for HTO had ELPS. Nonetheless, we did not find any risk factor related to the presence of ELPS. These results suggest that surgeons should be cautious when diagnosing concomitant ELPS despite acceptable radiographic findings from patellofemoral joints when performing HTO.

Influence of the severity of knee osteoarthritis on the association between leg muscle mass and quadriceps strength: the SPSS-OK study

Quadriceps strength is important for maintaining functional movement in patients with knee osteoarthritis (OA). We aimed to examine whether knee OA severity weakened the magnitude of the associations between leg muscle mass, quadriceps strength, and functional movement. Screening for People Suffering Sarcopenia in Orthopedic cohort of Kobe study (SPSS-OK) was a single-center cross-sectional study. We recruited 611 patients with knee OA. Leg muscle mass was determined by bioimpedance and used as a proxy for quadriceps muscle mass. Quadriceps strength and indices of functional movement (assessed by the functional activities category of the new Knee Society Score questionnaire [KSS] and the Timed Up and Go [TUG] test) were measured. Knee OA severity was determined by the Kellgren-Lawrence radiographic grade. A series of general linear models was fitted with adjustment for confounding variables. The increase in quadriceps strength per leg associated with a 1-kg increase in leg mass per leg was 7.29 Nm, 5.43 Nm, and 3.77 Nm among patients with knee OA grade 1/2, 3, and 4, respectively (P for interaction = 0.003). A 1-Nm increase in quadriceps strength per leg was associated with both a 0.14 point increase in KSS movement score and a 0.05 s decrease in TUG, regardless of knee OA severity (P for interaction 0.430 and 0.323). Severe knee OA may reduce efficiency in the exertion of quadriceps strength by leg muscle mass even when the amount of muscle mass remains unchanged.

Patellofemoral reconstruction for patellar instability with patella alta in middle-aged patients: Clinical outcomes

INTRODUCTION

Although several surgical treatments for patellar instability with patella alta have been reported, the clinical outcomes and optimal surgical procedures for patellar instability with patella alta in middle-aged patients are still controversial. We hypothesized that optimal surgical procedures for patellar instability with patella alta in middle-aged patients may induce good clinical outcomes with better patellofemoral geometry.

MATERIALS AND METHODS

Twelve middle-aged patients with a mean age of 44 years (range: 40-55 years), who presented with patellar instability and patella alta, were treated with a combination of several surgeries, such as medial patellofemoral ligament (MPFL) reconstruction, trochleoplasty, lateral release, and three-dimensional transfer of the tibial tuberosity, based on a surgical algorithm. Patellar position and clinical outcomes were evaluated postoperatively. The mean follow-up time was 41.5 months (range: 24-72 months).

RESULTS

Patellar position altered from 1.31 (1.21-1.53) preoperatively to 0.88 (0.69-1.06) postoperatively on the Caton-Deschamps Index (p<0.01). The tibial tuberosity-trochlear groove (TT-TG) distance altered from 21.8mm (20.1-25.8mm) to 10.3mm (5.1-14.7mm), and patellar tilt ranged from 28.1° (21-40°) to 14.6° (5-28°), respectively (p<0.01). Clinical outcomes on the Lysholm and Kujala scales improved from 43.1 and 38.4 to 86.7 and 78.3, respectively, at final follow-up (p<0.01). Surgical treatment that included trochleoplasty resulted in better outcomes than other surgical combinations without trochleoplasty (p<0.05). Sulcus angle and postoperative patellar tilt improved more in those who underwent trochleoplasty than in those who did not (p<0.05).

DISCUSSION

Surgical treatment for patellar instability with patella alta in middle-aged patients resulted in improved clinical outcomes. In particular, a combination surgery including trochleoplasty resulted in the greatest improvement in case of severe trochlear dysplasia.

LEVEL OF EVIDENCE

IV. Retrospective case series study.

Tibial Tuberosity-Trochlear Groove Distance Shows no Change in Patients with or Without Knee Osteoarthritis

Objective

The primary aim of this study is to compare tibial tuberosity-trochlear groove (TTTG) distance in patients with or without knee osteoarthritis. Additionally, the variability of tibial tubercle according to trochlear groove was evaluated.

Materials and Methods

In this retrospective cohort study, TTTG distance was measured with two different methods on magnetic resonance (MR) images. TTTG distance was measured by the familiar method on 173 MR images, and by the novel method on 157 MR images of 175 patients totally. The patients were divided into two groups as group 1 (Kellgren Lawrence osteoarthritis grade <2) and group 2 (Kellgren Lawrence osteoarthritis grade ≥2). TTTG values measured by both methods were compared between groups. The coefficient of variation for all patients in TTTG values were calculated. A p-value <0.05 was considered as significant.

Results

The mean age, sex distributions, and side ratios were different between groups. There was no statistical difference in TTTG values between group 1 and 2. There was no statistically significant difference between the two measurement methods. The coefficient of variation for all patients in TTTG values were high (43.95% for familiar method and 44.64% for novel method). There was excellent interrater reliability for two measurement methods in both groups.

Conclusion

The TTTG distance is similar in patients with/without knee osteoarthritis. The position of the tibial tubercle according to the trochlear groove is variable, so the tibial tubercle may not be a good reference point for rotational position of the tibial component in total knee arthroplasty.

Influence of age on clinical outcomes of three-dimensional transfer of the tibial tuberosity for patellar instability with patella alta

PURPOSE

To evaluate the clinical outcomes of three-dimensional (3D) transfer of the tibial tuberosity for patellar instability with patella alta, with a focus on the influence of age at initial surgery.

METHODS

Three-dimensional surgery was performed on 28 knees with a mean follow-up of 46 months. Patients were separated into three groups based on the age at initial surgery: group A, 10 knees and an average age of 16.3 ± 1.8 (14-19) years; group B, 10 knees and an average age of 22.1 ± 2.5 (20-28) years; and group C, eight knees and an average age of 44.0 ± 2.2 (40-46) years. Patellofemoral geometry improvement focused on patella alta by determining the Insall-Salvati ratio and Caton-Deschamps index, rotational malalignment by measuring the tibial tubercle-trochlear groove (TT-TG) distance, and lateral patellar subluxation by measuring the patellar tilt. Clinical outcomes were evaluated by the Lysholm and Kujala scores, which were compared before and after surgery. Cartilage degeneration was evaluated by the International Cartilage Repair Society grading system at initial arthroscopy.

RESULTS

The patellar height, TT-TG, and patellar tilt significantly improved in all groups postoperatively (p < 0.05). The Lysholm and Kujala scores also significantly improved postoperatively; however, both scores were lower in group C than in the other groups (p < 0.05). Particularly, pain scores were more severe in group C than in the other groups, and the severity of cartilage degeneration correlated with the pain scores (p < 0.05). Cartilage damage differed significantly between the groups at initial arthroscopy; particularly, group C included grades III and IV cartilage degeneration (p < 0.05).

CONCLUSIONS

Age at initial surgery may be the predicting factor for poor clinical outcomes of 3D transfer surgery. The clinical outcome may depend on the age at surgery, which correlated with cartilage damage; thus, surgeons should be given this information when patients are considered undergoing patella surgery.

LEVEL OF EVIDENCE

Therapeutic case series, Level IV.

Comparison of Lateral Closing-Wedge Versus Medial Opening-Wedge High Tibial Osteotomy on Knee Joint Alignment and Kinematics in the ACL-Deficient Knee

BACKGROUND

Lateral closing-wedge (LCW) and medial opening-wedge (MOW) high tibial osteotomies (HTOs) correct varus knee alignment and stabilize the anterior cruciate ligament (ACL)-deficient knee. Tibiofemoral and patellofemoral alignment and kinematics after HTO are not well quantified.

PURPOSE

To compare the effect of LCW and MOW HTO on tibiofemoral and patellofemoral alignment in the ACL-deficient knee.

STUDY DESIGN

Controlled laboratory study.

METHODS

Anterior drawer, Lachman, and pivot-shift tests were performed on cadaveric specimens (N = 16), and anterior tibial translation and tibial rotation were measured for the native and ACL-sectioned knee. The right and left knee of each cadaveric specimen underwent an LCW and MOW HTO, respectively, and stability testing was repeated. All cadavers underwent pre- and postosteotomy computerized tomography with 3-dimensional computer modeling to determine the effect of HTO on posterior tibial slope, as well as tibial and patellofemoral axial plane alignment (tibial axial rotation and patellar axial tilt).

RESULTS

Correction to neutral coronal alignment was obtained with both osteotomy techniques; however, larger posterior tibial slope neutralization was achieved with LCW compared with MOW (mean ± SD, 11° ± 3.8° vs 5° ± 5°). LCW demonstrated a greater decrease in anterior tibial translation (P < .05) during Lachman testing, with translation values approximating those of the native knee, especially for the lateral compartment. A similar decrease in anterior tibial translation with LCW was not found during anterior drawer testing. Anterior tibial translation did not improve for either the Lachman or the anterior drawer test after MOW. Osteotomy type did not affect tibial rotation with pivot shift. Relative to MOW, LCW resulted in greater tibial axial rotation and patellar axial tilt (7.7° ± 4° and 5.6° ± 3.9° [LCW], 2.8° ± 2.3° and 2.4° ± 0.9° [MOW], respectively; P < .05).

CONCLUSION/CLINICAL RELEVANCE

LCW shows more reproducible posterior tibial slope neutralization and decreased anterior tibial translation in ACL deficiency compared with MOW; however, LCW is associated with increased external tibial axial rotation and lateral patellar tilt, which may adversely affect the patellofemoral joint. More work is needed to understand the clinical and functional outcome of these biomechanical findings in the ACL-deficient knee.

Sport and early osteoarthritis: the role of sport in aetiology, progression and treatment of knee osteoarthritis

Sports activities are considered favourable for general health; nevertheless, a possible influence of sports practice on the development of early osteoarthritis (OA) is a cause for concern. A higher incidence of OA in knees and ankles of former high-impact sports players than in those of the normal population has been shown and it is still debatable whether the cause is either to be recognized generically in the higher number of injuries or in a joint overload. The possibility to address knee OA in its early phases may be strictly connected to the modification of specific extrinsic or intrinsic factors, related to the patient in order to save the joint from further disease progression; these include sport practice, equipment and load. Non-surgical therapies such as continuative muscles reinforce and training play a strong role in the care of athletes with early OA, particularly if professional. There is an overall agreement on the need of an early restoring of a proper meniscal, ligament and cartilage integrity in order to protect the knee and resume sports safely, whereas alignment is a point still strongly debatable especially for professional athletes. Remaining questions still to be answered are the risks of different sports in relation to one another, although an actual protective effect of low-impact sports, such as walking, swimming or cycling, has been recognized on the appearance or worsening of OA, the effect of continuing or ceasing to practice a sport on the natural history of early OA, and even following appropriate treatment is still unknown.