Knee Osteotomy Decreases Joint Inflammation Based on Synovial Histology and Synovial Fluid Analysis.

PURPOSE: To examine the biological changes in the joints of patients with knee osteoarthritis (OA) before and after around-knee osteotomy (AKO), focusing on synovial fluid (SF) and synovial pathological changes. METHODS: Patients who underwent AKO for medial compartment knee OA between 2019 and 2021 were examined. SF and synovium were obtained at the time of AKO and plate removal after bone union (mean, 16.8 months [range: 11-38 months] postoperatively). SF volume and interleukin (IL)-6 concentrations in SF were assayed using enzyme-linked immunosorbent assay. Synovitis was assessed histologically using a semiquantitative scoring system. Macrophage infiltration was assessed by immunohistochemistry using a semiquantitative score for F4/80 expression. The M1/M2 ratio was calculated using percentage of cells positive for CD80 and CD163. The expression of proinflammatory cytokines was assessed by the percentage of IL-1ß- and IL-6-positive cells. The number of vascular endothelial growth factor-positive luminal structures was counted to assess angiogenesis. The change in each parameter was compared before and after AKO using the Wilcoxon matched-pairs signed-rank test. RESULTS: Twenty-four knees of 21 patients were included. SF volume and IL-6 concentration significantly decreased postoperatively (12.6 ± 2.1 mL vs 4.2 ± 0.6 mL; P < .0001 and 50.5 ± 8.6 pg/mL vs 20.7 ± 3.8 pg/mL; P = .0001, respectively). A significant reduction in synovitis score (P = .0001), macrophage infiltration (P < .0003), M1/M2 ratio (P < .0007), angiogenesis (P < .0001), and the percentage of IL-1ß- and IL-6-positive cells in the intima (P < .008 and P < .002, respectively) was found after AKO. CONCLUSIONS: SF volume and IL-6 concentrations in the SF decreased and inflammatory synovium pathology improved after AKO. In addition to biomechanical changes, the biological environment of the joint can be improved after AKO. LEVEL OF EVIDENCE: Level IV, retrospective therapeutic case series.

Symmetry in knee arthrokinematics in healthy collegiate athletes during fast running and drop jump revealed through dynamic biplane radiography.

OBJECTIVE: Changes in cartilage contact area and/or contact location after knee injury can initiate and exacerbate cartilage degeneration. Typically, the contralateral knee is used as a surrogate for native cartilage contact patterns on the injured knee. However, symmetry in cartilage contact patterns between healthy knees during high-impact activities is unknown. METHOD: Tibiofemoral kinematics were measured on 19 collegiate athletes during fast running and drop jump using dynamic biplane radiography and a validated registration process that matched computed tomography (CT)-based bone models to the biplane radiographs. Cartilage contact area and location were measured with participant-specific magnetic resonance imaging (MRI)-based cartilage models superimposed on the CT-based bone models. Symmetry in cartilage contact area and location was assessed by the absolute side-to-side differences (SSD) within participants. RESULTS: The SSD in contact area during running (7.7 ± 6.1% and 8.0 ± 4.6% in the medial and lateral compartments, respectively) was greater than during drop jump (4.2 ± 3.7% and 5.7 ± 2.6%, respectively) (95% CI of the difference: medial [2.4%, 6.6%], lateral [1.5%, 4.9%]). The average SSD in contact location was 3.5 mm or less in the anterior-posterior (AP) direction and 2.1 mm or less in the medial-lateral (ML) direction on the femur and tibia for both activities. The SSD in AP contact location on the femur was greater during running than during drop jump (95% CI of the difference: medial [1.6 mm, 3.6 mm], lateral [0.6 mm, 1.9 mm]). CONCLUSION: This study provides context for interpreting results from previous studies on tibiofemoral arthrokinematics. Previously reported differences between ligament-repaired and contralateral knee arthrokinematics fall within the range of typical SSDs observed in healthy athletes. Previously reported arthrokinematics differences that exceed SSDs found in these healthy athletes occur only in the presence of anterior cruciate ligament (ACL) deficiency or meniscectomy.

Development and Analysis of Mouse Medial Meniscus Posterior Root Tear Model.

Medial meniscus posterior root tears (MMPRT) are often associated with osteoarthritis (OA) progression and subchondral bone insufficiency fractures. This study aimed to develop the first MMPRT mouse model. The MMPRT model was created by sectioning the medial meniscus posterior root of 12-week-old CL57BL/6J male mice under stereomicroscopic observation. The sham operation and the destabilization of the medial meniscus (DMM) model groups were also created. OA progression and subchondral bone changes were evaluated histologically using the Osteoarthritis Research Society International (OARSI) subchondral bone scoring system at 2, 4, 8, and 12 weeks after surgery. Microcomputed tomography (µCT) was performed to evaluate the presence of insufficient fractures. OA progression and medial meniscus extrusion were observed in the MMPRT and DMM models 12 weeks after surgery. OA progressed in both models during the time course, without a significant difference in the OARSI score between the two groups. The subchondral bone score was significantly higher at 12 weeks than at 2 and 4 weeks in the MMPRT group, while no significant difference was found between the two groups. In the µCT analysis, destruction of the medial tibial plateau was observed in 4/40 knees, while none were observed in the DMM group. Of the four knees, destruction of the medial femoral condyle was also observed in three knees. Characteristic pathological changes were observed in the mouse MMPRT model. The mouse MMPRT model may be useful for investigating pathological changes after MMPRT.

Potential Interaction between Sodium Polystyrene Sulfonate and Prescription Drugs in Artificial Intestinal Juice.

This study evaluated the interaction between sodium polystyrene sulfonate (SPS) and several commonly used concomitant drugs, such as carvedilol, bisoprolol, imidapril, atorvastatin and azilsartan. The residual rate of adsorption 6 h after starting the experiment followed the order carvedilol (0.36%) < bisoprolol (19.7%) < imidapril (81.2%) < atorvastatin (86.5%) < azilsartan (87.9%) in artificial intestinal juice (pH 6.8). In addition, the pKa of carvedilol and bisoprolol was 8.0 and 9.6 and that of atorvastatin, azilsartan, and imidapril was 4.5, 6.1, and 2.4, respectively. These results indicate that the form (ionic or uncharged) of each drug is important to its reaction with SPS. Moreover, we demonstrated the effect of potassium ions (concentration of 1000 or 2000 mg/L) on the adsorption of concomitant drugs onto SPS in artificial intestinal juice. Our results show that the residual rate of adsorption of carvedilol and bisoprolol increases with increasing concentration of potassium ions whereas adsorption of potassium ions onto SPS was unaffected by carvedilol and bisoprolol under our experimental conditions. Finally, the obtained results revealed that interactions between SPS and carvedilol or bisoprolol readily occur in artificial intestinal juice.

Posterior tibial slope and meniscal slope correlate with in vivo tibial internal rotation during running and drop jump.

PURPOSE: The relationship between tibial bony and meniscus anatomy and knee kinematics during in vivo, high-impact activities remains unclear. This study aimed to determine if the posterior tibial slope (PTS) and meniscal slope (MS) are associated with in vivo anterior-posterior translation and internal tibia rotation during running and double-leg drop jumps in healthy knees. METHODS: Nineteen collegiate athletes performed fast running at 5.0 m/s on an instrumented treadmill and double-leg drop jump from a 60 cm platform while biplane radiographs of the knee were acquired at 150 Hz. Tibiofemoral kinematics were determined using a validated model-based tracking process. Medial and lateral PTS and MS were measured using magnetic resonance imaging (MRI). RESULTS: In fast running, more internal tibia rotation was associated with greater PTS (ρ = 0.336, P = 0.039) and MS (ρ = 0.405, P = 0.012) in the medial knee compartment. In the double-leg drop jump, more internal tibia rotation was associated with greater PTS (ρ = 0.431, P = 0.007) and MS (ρ = 0.323, P = 0.005) in the medial knee compartment, as well as a greater PTS in the lateral knee compartment (ρ = 0.445, P = 0.005). CONCLUSION: These findings suggest that the medial and lateral PTS and medial MS are associated with the amount of knee rotation during high-impact activities. These in vivo findings improve our understanding of ACL injury risk by linking bone and meniscus morphology to dynamic kinematics.

Combining age, sex, body mass index, sport level, and preoperative quadriceps strength improves the predictive ability of quadriceps strength recovery after anterior cruciate ligament reconstruction.

PURPOSE: This study compared the predictive ability of each independent predictor with that of a combination of predictors for quadriceps strength recovery one year after anterior cruciate ligament (ACL) reconstruction. METHODS: Patients who underwent primary ACL reconstruction using hamstring autografts were enrolled. Quadriceps strength, hamstring strength, and anterior tibial translation were measured, and the limb symmetry index (LSI) of the quadriceps and the hamstrings was calculated preoperatively and one year after surgery. Patients were classified into two groups according to the LSI of the quadriceps strength at one year postoperatively (≥ 80% or < 80%). Multivariate logistic regression analysis identified the independent predictors of quadriceps strength recovery, and the cut-off value was calculated using the receiver operating characteristic curve. A model assessing predictive ability of the combination of independent predictors was created, and the area under the curve (AUC) for each independent predictor was calculated by using the receiver-operating characteristic curves and the DeLong method. RESULTS: Of the 646 patients, 414 (64.1%) had an LSI of at least 80% for quadriceps strength one year after surgery, and 232 patients (35.9%) had an LSI of < 80%. Age, sex, body mass index (BMI), preinjury sport level, and LSI of preoperative quadriceps strength were independently associated with quadriceps strength recovery one year after ACL reconstruction. The cut-off values were age: 22.5 years; sex: female; BMI: 24.3 kg/m2; preinjury sport level: no sport; and LSI of preoperative quadriceps strength: 63.3%. The AUC of the model assessing the predictive ability of the combination of age, sex, BMI, preinjury sport level, and LSI of preoperative quadriceps strength was significantly higher (0.73) than that of similar factors of preoperative quadriceps strength (AUC: 0.63, 0.53, 0.56, 0.61, and 0.68, p < 0.01, respectively). CONCLUSION: The combination of age, sex, BMI, preinjury sport level, and LSI of preoperative quadriceps strength had a superior predictive ability for quadriceps strength recovery at one year after ACL reconstruction than these predictors alone. Multiple factors, including patient characteristics and preoperative quadriceps strength, should be considered when planning rehabilitation programs to improve quadriceps strength recovery after ACL reconstruction. LEVEL OF EVIDENCE: III.

Talar component subsidence correlates with periprosthetic osteolysis after total ankle arthroplasty.

PURPOSE: This study aimed to investigate the relationship between periprosthetic osteolysis around the talar component and the amount of talar component subsidence after total ankle arthroplasty (TAA). METHODS: This study included forty patients who underwent TAA with a mean follow-up of 67.5 ± 17.0 months. The patients were divided into two groups based on the amount of osteolysis around the talar component, as measured by computed tomography at the latest clinic visit: none to 2 mm (N group, n = 20) and greater than or equal to 2 mm (O group, n = 20). The average amount of talar component subsidence, clinical outcomes, and complications were compared between the two groups. In the O group, the correlation between osteolysis and talar component subsidence was evaluated. RESULTS: The average talar component subsidence was significantly different between the N (0.22 ± 0.94 mm) and O groups (2.12 ± 2.28 mm). Five out of 20 ankles in the O group required revision surgery owing to talar component subsidence. The Japanese Society for Surgery of the Foot scores in the N and O groups were significantly different: 93.5 ± 7.7 and 85.3 ± 15.4, respectively. In the O group, we found that osteolysis tended to develop on the lateral side, and the amount of osteolysis was positively correlated with the talar component subsidence (r = 0.59, P = .007). CONCLUSION: In the O group, a positive correlation between osteolysis and talar component subsidence was found, and five patients required revision surgery.

Fundamental Investigation of Adsorption Behavior onto Sodium Polystyrene Sulfonate to Potassium Ions and Its Concomitant Drugs in the Digestive Tract.

To verify the interaction between sodium polystyrene sulfonate (SPS) and its concomitant drugs, we elucidated the capability of potassium ions and concomitant drugs to adsorb onto SPS and the effect of their coexistence on the amount adsorbed. We identified 14 drugs used concomitantly with SPS from 2017-2019 in our investigation, and 5 drug preparations used in the clinical setting were used for the experiments. In the artificial intestinal juice, SPS adsorbed 39.05-69.77 mEq/g of potassium ions. Amlodipine besylate and nifedipine were well-adsorbed, while azosemide and febuxostat were did not adsorb well onto SPS. Our results and the results of a previous study suggest that additives in drug preparations affect the adsorption of drugs onto SPS. The adsorption kinetics onto SPS of drugs conformed to the pseudo-second order model. However, the adsorption of amlodipine besylate completely may not be fitted to the pseudo-second order model. The amount of amlodipine besylate adsorbed under the coexistence of potassium ions decreased compared to when potassium ions were absent. The amount of nifedipine and potassium ions adsorbed remained constant, regardless of whether potassium ions were present or not. These results might be due to the differences in their mechanisms of adsorption onto SPS and to the characteristics of the drugs. In a clinical setting, SPS is used concomitantly with various oral drugs. The interaction between SPS and its other concomitant drugs need to be elucidated more to obtain enough evidence for pharmacists to propose the appropriate prescription.

The effect of lateral extra-articular tenodesis on in vivo cartilage contact in combined anterior cruciate ligament reconstruction.

PURPOSE: Lateral extra-articular tenodesis (LET) may confer improved rotational stability after anterior cruciate ligament reconstruction (ACLR). Little is known about how LET affects in vivo cartilage contact after ACLR. The aim of this study was to investigate the effect of LET in combination with ACLR (ACLR + LET) on in vivo cartilage contact kinematics compared to isolated ACLR (ACLR) during downhill running. It was hypothesised that cartilage contact area in the lateral compartment would be larger in ACLR + LET compared with ACLR, and that the anterior-posterior (A-P) position of the contact center on the lateral tibia would be more anterior after ACLR + LET than after ACLR. METHODS: Twenty patients were randomly assigned into ACLR + LET or ACLR during surgery (ClinicalTrials.gov:NCT02913404). At 6 months and 12 months after surgery, participants were imaged during downhill running using biplane radiography. Tibiofemoral motion was tracked using a validated registration process. Patient-specific cartilage models, obtained from 3 T MRI, were registered to track bone models and used to calculate the dynamic cartilage contact area and center of cartilage contact in both the medial and lateral tibiofemoral compartments, respectively. The side-to-side differences (SSD) were compared between groups using a Mann-Whitney U test. RESULTS: At 6 months after surgery, the SSD in A-P cartilage contact center in ACLR + LET (3.9 ± 2.6 mm, 4.4 ± 3.1 mm) was larger than in ACLR (1.2 ± 1.6 mm, 1.5 ± 2.0 mm) at 10% and 20% of the gait cycle, respectively (p < 0.01, p < 0.05). There was no difference in the SSD in cartilage contact center at 12 months after surgery. There was no difference in SSD of cartilage contact area in the medial and lateral compartments at both 6 and 12 months after surgery. There were no adverse events during the trial. CONCLUSION: LET in combination with ACLR may affect the cartilage contact center during downhill running in the early post-operation phase, but this effect is lost in the longer term. This suggests that healing and neuromuscular adaptation occur over time and may also indicate a dampening of the effect of LET over time. (337 /350 words) LEVEL OF EVIDENCE: Level II.

Analysis of bone union after medial closing wedge distal femoral osteotomy using a new radiographic scoring system.

INTRODUCTION: To compare bone union after medial closing wedge distal femoral osteotomy (MCWDFO) with that after lateral closing wedge distal femoral osteotomy (LCWDFO) using a novel scoring system. MATERIALS AND METHODS: The data of 30 patients who received biplanar MCWDFO for valgus knees (MCWDFO group) were retrospectively examined and compared to that of 22 patients (25 knees) who underwent biplanar LCWDFO via a double-level osteotomy (DLO) for varus knees (LCWDFO group). The progression of bone union of the transverse osteotomy plane in the femur was assessed using a newly developed scoring system using radiographs taken immediately after surgery and 3 and 6 months postoperatively. The scoring system is based on a scale of zero to six points with higher scores indicating better bone union. The incidence of hinge fractures was assessed using CT images, and the rates of reoperation were evaluated using medical record data. RESULTS: The mean bone union score was significantly lower in the MCWDFO group than in the LCWDFO group 3 months (2.1 ± 1.9 vs. 3.7 ± 1.7, P < 0.01) and 6 months (3.8 ± 2.1 vs 4.9 ± 1.5, P < 0.05) postoperatively. The incidence ratio of hinge fractures was significantly higher in the MCWDFO group than in the LCWDFO group (70.0% vs. 32.0%, P < 0.01). Two patients in the MCWDFO group underwent reoperation for delayed bone union or non-union. CONCLUSION: Bone union progression was slower and hinge fractures were more frequently observed after MCWDFO than after LCWDFO via DLO. MCWDFO is technically challenging, and patients must be monitored closely during and after surgery.

Knee Osteoarthritis Progression Is Delayed in Silent Information Regulator 2 Ortholog 1 Knock-in Mice.

Overexpression of silent information regulator 2 ortholog 1 (SIRT1) is associated with beneficial roles in aging-related diseases; however, the effects of SIRT1 overexpression on osteoarthritis (OA) progression have not yet been studied. The aim of this study was to investigate OA progression in SIRT1-KI mice using a mouse OA model. OA was induced via destabilization of the medial meniscus using 12-week-old SIRT1-KI and wild type (control) mice. OA progression was evaluated histologically based on the Osteoarthritis Research Society International (OARSI) score at 4, 8, 12, and 16 weeks after surgery. The production of SIRT1, type II collagen, MMP-13, ADAMTS-5, cleaved caspase 3, Poly (ADP-ribose) polymerase (PARP) p85, acetylated NF-κB p65, interleukin 1 beta (IL-1ß), and IL-6 was examined via immunostaining. The OARSI scores were significantly lower in SIRT1-KI mice than those in control mice at 8, 12, and 16 weeks after surgery. The proportion of SIRT1 and type II collagen-positive-chondrocytes was significantly higher in SIRT1-KI mice than that in control mice. Moreover, the proportion of MMP-13-, ADAMTS-5-, cleaved caspase 3-, PARP p85-, acetylated NF-κB p65-, IL-1ß-, and IL-6-positive chondrocytes was significantly lower in SIRT1-KI mice than that in control mice. The mechanically induced OA progression was delayed in SIRT1-KI mice compared to that in control mice. Therefore, overexpression of SIRT1 may represent a mechanism for delaying OA progression.

The Influences of Chronicity and Meniscal Injuries on Pivot Shift in Anterior Cruciate Ligament-Deficient Knees: Quantitative Evaluation Using an Electromagnetic Measurement System.

PURPOSE: To investigate the influences of time from injury to surgery and meniscal injuries on knee rotational laxity in anterior cruciate ligament (ACL)-deficient knees using the electromagnetic system retrospectively. METHODS: Ninety-four unilateral ACL-injured patients (44 male and 50 female, mean age: 27.3 ± 11.8 years) were included. The pivot-shift test was performed before ACL reconstruction, as was a quantitative evaluation using the electromagnetic system to determine tibial acceleration. Patients were divided into 4 groups according to the chronicity: group 1, within 3 months (22 patients); group 2, between 3 and 6 months (29 patients); group 3, between 6 and 12 months (23 patients); and group 4, more than 12 months (20 patients). The presence of meniscal injuries was examined arthroscopically. RESULTS: The tibial acceleration was significantly greater in group 4. There was a positive correlation between tibial acceleration and the time from injury to surgery (r = 0.47, P = .02). In groups 1, 2 and 3, the tibial acceleration in patients with a lateral meniscal injury was significantly greater than in patients with a medial meniscal injury and without meniscal injury. When patients with lateral meniscal injury were excluded (leaving those with medial meniscus injury or without meniscal injury), group 4 had significantly greater accelerations than other groups. CONCLUSIONS: In ACL-deficient knees, rotational laxity increased with time and the increased rotational laxity was evident more than 1 year after injury whereas it increased with concomitant lateral meniscal injuries within 1 year after injury. LEVEL OF EVIDENCE: Ⅳ, diagnostic study of nonconsecutive patients.

MRI-determined anterolateral capsule injury did not affect the pivot-shift in anterior cruciate ligament-injured knees.

PURPOSE: The purpose of this study was to quantitatively compare the results of pivot-shift test between knees with anterior cruciate ligament (ACL) injury with and without anterolateral capsule (ALC) injury detected on MRI. ALC injury was hypothesized to worsen rotatory knee laxity. METHODS: 82 patients with unilateral ACL injury were enrolled in this study. The pivot-shift test was performed under anesthesia before ACL reconstruction. Two evaluations were conducted simultaneously: IKDC clinical grading and the quantitative evaluation using an electromagnetic measurement system that determined tibial acceleration (m/s2). Two examiners identified the ALC injury on magnetic resonance imaging (MRI) and stratified patients into two groups: ALC-injured (ALC+) and ALC-intact (ALC-). ALC injury was diagnosed if the signal intensity on coronal T2-weighted sequences is increased. After confirming the reliability of the MRI, the difference in the pivot-shift between two groups was assessed. RESULTS: Because of the poor agreement between examiners with respect to the ALC evaluations (κ coefficient of 0.25 and 58.5% concordance), the result from each examiner was analyzed separately. Examiner 1 found ALC injury in 42/82 knees (51%). The two groups had similar clinical grading (glide/clunk/gross: ALC+ group 21/18/3cases vs. ALC- group 21/16/3cases) (n.s.). Tibial acceleration during pivot-shift was also similar in the ALC+ (1.4 ± 1.2 m/s2) and ALC- (1.7 ± 1.3 m/s2) groups (n.s.). Examiner 2 found ALC injury in 28/82 knees (34%). Differences in clinical grading were not observed (glide/clunk/gross: ALC+ group 16/9/3 vs. ALC- group 26/25/3) (n.s.). However, the tibial acceleration in the ALC+ group (1.2 ± 0.8 m/s2) was significantly lower than that in the ALC- group (1.7 ± 1.3 m/s2, p = 0.03). CONCLUSION: Concomitant ALC injury in knees with ACL injury was not consistently detected on MRI and did not affect rotatory knee laxity. LEVEL OF EVIDENCE: Case-control study, level III.

The concomitant lateral meniscus injury increased the pivot shift in the anterior cruciate ligament-injured knee.

PURPOSE: Concomitant meniscus injuries in the anterior cruciate ligament (ACL) have been suggested to exacerbate rotational laxity. However, the effect is supposed to be so small, if any, that some quantitative pivot-shift measurement is needed. The purpose of this prospective study was to determine the effect of meniscus tear on rotational laxity in ACL-deficient knees by an quantitative measurement. It was hypothesized that a concomitant meniscus tear, especially a lateral one, would induce greater pivot shift. METHODS: Fifty-seven unilateral ACL-injured patients (26 men and 31 women, mean age: 24 ± 10 years) were included. The pivot-shift test was performed prior to ACL reconstruction, while a quantitative evaluation using an electromagnetic system to determine tibial acceleration and a clinical grading according to the IKDC were performed. Meniscus injuries were diagnosed arthroscopically, and concomitant meniscus tear was confirmed in 32 knees. RESULTS: The clinical grade was not different between the ACL-injured knees of patients with and without meniscus tear (n.s.). Tibial acceleration did not show a statistical significant difference (meniscus-injured knees: 1.6 ± 1.1 m/s2 versus meniscus-intact knees: 1.2 ± 0.7 m/s2, n.s.). However, the subgroup analysis demonstrated that there was increased tibial acceleration in ACL-deficient knees with lateral meniscus tear (2.1 ± 1.1 m/s2, n = 13) compared with meniscus-intact knees (p < 0.05), whereas rotational laxity did not increase in the medial meniscus-injured and bilateral-injured knees (1.2 ± 0.9 m/s2, n = 12, n.s. and 1.4 ± 1.1 m/s2, n = 7, n.s., respectively). CONCLUSION: A concomitant meniscus tear, especially a lateral meniscus tear, has a significant impact on rotational laxity in ACL-injured knees. When a large pivot shift is observed in the ACL-injured knee, a concomitant meniscus tear should be suspected and an aggressive treatment would be considered. Meniscus injuries should be inspected carefully when substantial pivot shift is encountered in ACL-injured knees. LEVEL OF EVIDENCE: Diagnostic study, Level III.

Deterioration of patellofemoral cartilage status after medial open-wedge high tibial osteotomy.

PURPOSE: To identify parameters associated with deterioration of patellofemoral (PF) cartilage after open-wedge high tibial osteotomy (OWHTO) and determine predictive values. It was hypothesized that cartilage injuries in PF joints would progress after OWHTO in patients who need a large alignment correction. METHODS: Fifty-two knees in 47 patients who underwent bi-planer OWHTO for the treatment of medial compartment osteoarthritis from 2012 to 2017 and received a second-look arthroscopy at the time of plate removal (mean 14 months post-OWHTO) were assessed. Clinical outcomes were evaluated by the Knee Society Scores. Cartilage status in PF joints were evaluated arthroscopically using the International Cartilage Repair Society (ICRS) grading system. Patients were divided into two groups and patients who had progressed PF cartilage injury (progressed group) were compared with those who did not have progressed PF cartilage injuries (non-progressed group) using various parameters. The relationships between medial opening gap or change in the medial proximal tibial angle (ΔmPTA) and progression of PF cartilage injuries were examined by receiver operating characteristic (ROC) curve analysis. RESULTS: The mean Knee Society Scores were significantly improved after surgery (P < 0.01). The grades for the patella and trochlea progressed in 12 (23.0%) and 16 knees (30.8%), respectively. The mean preoperative hip-knee-ankle (HKA) angle, mechanical axis, and mPTA in the progressed group were significantly smaller than those in the non-progressed group (P < 0.01). The mean medial opening gap and ΔmPTA in the progressed group were significantly larger than those in the non-progressed group (P < 0.01). ROC curve analysis showed that the cut-off values of the medial opening gap and ΔmPTA for progression of PF cartilage injuries were 13 mm and 9°, respectively. Progression of PF cartilage injuries was more frequently observed in knees with a medial opening gap ≥ 13 mm (P = 0.019, odds ratio = 4.60) or a ΔmPTA ≥ 9° (P = 0.003, odds ratio 6.93) than knees with those of < 13 mm or 9°, respectively. CONCLUSIONS: Cartilage injuries in PF joints tended to progress after OWHTO in patients with medial opening gap ≥ 13 mm or ΔmPTA ≥ 9°. If medial opening gap is ≥ 13 mm or ΔmPTA is ≥ 9° in planning for OWHTO, other type of surgery may need to be considered to avoid early progression of PF cartilage injuries. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Influence of limb alignment and prosthetic orientation on patient-reported clinical outcomes in total knee arthroplasty.

BACKGROUND: The relationship between postoperative limb alignment and clinical outcomes in primary total knee arthroplasty (TKA) is well reported, but the instruments used to evaluate clinical outcomes of TKA are mainly scoring systems from the physician's viewpoint, not patient-reported outcomes. The purpose of this study was to investigate retrospectively the relationship between postoperative limb alignment and patient-reported clinical outcomes using the 2011 Knee Society Knee Scoring System (2011 KSS). METHODS: The present study included 155 knees of patients (median age, 74 years) who underwent primary TKA for varus osteoarthritis, with a mean follow-up period of 46 months. The subjects were divided into three groups based on postoperative limb alignment and femoral and tibial component positioning angle (varus, neutral, and valgus). The 2011 KSS scores were compared among the groups. RESULTS: For limb alignment, the postoperative objective knee indicator score was significantly lower in the valgus group than in the varus and neutral groups, whereas no significant differences were observed in any subjective categories of the 2011 KSS. However, for the femoral component angle, functional activity scores were significantly lower in the valgus group than in the varus and neutral groups. CONCLUSIONS: The subjective patient-reported score was not affected by the postoperative limb alignment. However, the valgus femoral component angle resulted in lower subjective functional scores. For clinical relevance, postoperative valgus positioning of femoral component should be avoided from patient-reported functional aspects during TKA.

The diagnostic reliability of the quantitative pivot-shift evaluation using an electromagnetic measurement system for anterior cruciate ligament deficiency was superior to those of the accelerometer and iPad image analysis.

PURPOSE: Several non-invasive devices have been developed to obtain quantitative assessment of the pivot-shift test in clinical setting using similar but diverse measurement parameters. However, the clinical usability of those measurements has yet to be closely investigated and compared. The purpose of this study was to compare the diagnostic accuracy of three non-invasive measurement devices for the pivot-shift test. METHODS: Thirty patients with unilateral anterior cruciate ligament (ACL) injury were enrolled. The pivot-shift test was performed under general anaesthesia. Three devices, an accelerometer system (KiRA), an image analysis iPad application (iPad), and electromagnetic measurement system (EMS), were used simultaneously to provide two parameters, namely tibial acceleration monitored using KiRA and EMS, and tibial translation recorded using iPad and EMS. Side-to-side differences in each parameter and correlation between the measurements were tested, and a receiver-operating characteristic (ROC) curve analysis was conducted to compare their measurement accuracy. RESULTS: Significant side-to-side differences were successfully detected using any of the measurements (all p < 0.01). KiRA demonstrated moderate correlation with the EMS for tibial acceleration (r = 0.54; p < 0.01), while poor correlation was observed between iPad and the EMS for the translation (r = 0.28; p < 0.01). The ROC curve analysis demonstrated better accuracy for the detection of ACL insufficiency in the EMS than KiRA and iPad for tibial acceleration and translation, respectively. CONCLUSIONS: Although all three measurements were similarly capable of detecting ACL deficiency, the EMS has the advantage of comprehensive evaluation of the pivot-shift test by evaluating both tibial acceleration and translation with higher accuracy than those of KiRA and iPad. It could be suggested that any of those measurement tools might improve the clinical diagnosis of ACL insufficiency. LEVEL OF EVIDENCE: Diagnostic study of consecutive patients with a universally applied gold standard, Level Ib.

Remaining mild varus limb alignment leads to better clinical outcome in total knee arthroplasty for varus osteoarthritis.

PURPOSE: Postoperative neutral limb alignment [femorotibial mechanical axis (FTMA) 180° ± 3°] is generally considered to be one of the prerequisites for successful total knee arthroplasty (TKA). However, the influence of residual malalignment on clinical and functional outcomes after TKA is unknown. Therefore, the purpose of this study was to investigate the relationship between postoperative limb alignment and clinical outcomes in Asian patients who underwent primary TKA. METHODS: The study included 220 knees with a mean age of 73.5 years who underwent primary TKA for varus-type osteoarthritis; the mean follow-up period was 3.6 years. Patients were divided into four groups based on postoperative FTMA: severe varus (FTMA < 174°, n = 15), mild varus (FTMA >177°and ≤174°, n = 61), neutral (FTMA 180° ± 3°, n = 128), and valgus (FTMA > 183°, n = 16). Knee Society Knee Score (KSKS) and Knee Society Functional Score (KSFS) were compared among the 4 groups. RESULTS: KSKS and KSFS showed significant improvement in all groups. There were no statistically significant differences for postoperative KSKS among the four groups. For KSFS, however, the severe varus and valgus groups exhibited significantly lower values compared with the mild varus and neutral groups. CONCLUSION: Postoperative mild varus alignment as well as neutral mechanical alignment of the lower limb led to excellent functional outcomes. For the clinical relevance, postoperative mild varus alignment of the lower limb is acceptable following TKA for varus-type osteoarthritis. LEVEL OF EVIDENCE: IV.

The contribution of intraoperative medial compartment stability to post-operative knee flexion angle in unicompartmental knee arthroplasty.

PURPOSE: Given the knee kinematics and soft tissue balance in unicompartmental knee arthroplasty (UKA), it was hypothesised that intraoperative medial compartment stability will result in good functional outcome. The purpose of this study was to test the influence of soft tissue balance on post-operative knee flexion in UKA. METHODS: The influence of soft tissue balance on post-operative knee flexion in UKA was first examined retrospectively by using a newly developed tensor device in 30 consecutive patients diagnosed with either isolated medial compartmental osteoarthritis or idiopathic necrosis. The intraoperative component gap of the medial compartment was measured by using the tensor while applying a 20-lb joint distraction force at 0°, 10°, 30°, 45°, 60°, 90°, 120°, and 135° of knee flexion, with calculation of the joint looseness. Correlations between the soft tissue parameters and post-operative knee flexion angles were analysed 1 year after surgery. RESULTS: The post-operative knee flexion angle was negatively correlated with the component gap at 45°, 60°, and 90° of flexion (R = -0.41, P < 0.05; R = -0.44, P < 0.05; and R = -0.44, P < 0.05, respectively). Furthermore, the post-operative knee flexion angle was negatively correlated with joint looseness at 45°, 60°, and 90° of flexion (R = -0.40, P < 0.05; R = -0.41, P < 0.05; and R = -0.36, P < 0.05, respectively). CONCLUSIONS: The intraoperative medial compartment stability of knee flexion in midrange resulted in increasing post-operative knee flexion angle in UKA. Medial soft tissue release should be minimised, and assessment of soft tissue balance using a tensor can be performed to predict the post-operative knee flexion angle during surgery for UKA. LEVEL OF EVIDENCE: III.

Patient-based outcomes after medial patellofemoral ligament reconstruction.

PURPOSE: The purpose of this study was to evaluate subjective outcomes after medial patellofemoral ligament (MPFL) reconstructions. METHODS: Fifty-four knees of 46 patients who received MPFL reconstruction for recurrent patellar dislocations were examined with a minimum follow-up of two years. To assess patient-based outcomes, the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Kujala score were assessed. RESULTS: The mean Kujala score was significantly improved from 64.6 ± 22.1 pre-operatively to 84.7 ± 11.8 post-operatively (P < 0.001). The mean KOOS was also significantly improved post-operatively in all five subscales. Further, the mean scores of 41 out of the 42 questions for the KOOS were significantly improved after surgery, except those of the question about "grinding and clicking". When the KOOS was assessed individually, the scores on one or more subscales out of the five were worsened post-operatively in eight patients, and seven of the eight patients had decreased post-operative pain subscale scores. Furthermore, those eight patients (worse group) were compared with patients without any worsened scores on any of the subscales (better group). The mean pre-operative pain and sports/recreation function subscale scores were significantly higher in the worse group whereas the mean post-operative pain and symptoms subscale scores were significantly lower in the worse group than in the better group. CONCLUSIONS: Overall, satisfactory patient-based outcomes were obtained after MPFL reconstruction in most of the patients. However, patients who only have mild pain pre-operatively tend to have worse subjective outcomes, and a caution may be needed when performing MPFL reconstruction on these patients.