Early postoperative clinical recovery of robotic arm-assisted vs. image-based navigated Total hip Arthroplasty.

BACKGROUND: This study compared the early clinical recovery of total hip arthroplasty (THA) using computer navigation systems (nTHA) and robotic arm-assisted THA (rTHA). METHODS: Thirty prospective subjects who underwent rTHA were clinically compared to 30 subjects who underwent nTHA. Clinical data (surgical time, intraoperative blood loss, pain severity, number of days to independent walking, and Harris Hip Score (HHS) at discharge), and radiographic parameters (inclination and anteversion angles) were statistically compared between the two groups. RESULTS: Follow-up times were 24.3 ± 6.0 and 27.0 ± 7.0 days in the rTHA and nTHA groups, respectively. The surgical time (135.1 ± 13.9 min vs. 146.2 ± 12.8 min, p = 0.002), number of days to independent walking (7.2 ± 2.0 vs. 11.5 ± 3.0 days, p < 0.001), and postoperative pain using a numeric rating scale on postoperative days 7, 10,, and 14 (1.4 ± 0.9 vs. 2.2 ± 1.2, p = 0.005; 1.0 ± 0.8 vs. 1.8 ± 1.1, p = 0.002; 0.3 ± 0.5 vs. 1.1 ± 0.9, p < 0.001; respectively) were significantly reduced in the rTHA group compared to the nTHA group. The rTHA group showed a significantly higher postoperative HHS compared to the nTHA group (85.3 ± .3.2 vs. 81.0 ± 8.5, p = 0.014). No statistically significant difference was observed in radiographic parameters between the groups; however, the incidence of intraoperative target angle changes was significantly lower in the rTHA group than in the nTHA group (0/30 subjects [0%] vs. 11/30 subjects [36.7%], p < 0.001). CONCLUSION: The surgical time, postoperative pain, and number of days to independent walking were significantly shorter, and the HHS at discharge was significantly higher in the rTHA group than in the nTHA group. Thus, compared to the nTHA group, the rTHA group showed improved early clinical recovery.

Mid-flexion stability in the anteroposterior plane is achieved with a medial congruent insert in cruciate-retaining total knee arthroplasty for varus osteoarthritis.

PURPOSE: This study aimed to compare the intraoperative kinematics, especially for mid-flexion femorotibial anteroposterior (AP) stability, between newly developed medial congruent (MC) inserts and cruciate-retaining (CR) inserts in navigated cruciate-retaining total knee arthroplasty (CR-TKA). METHODS: Thirty consecutive patients with varus osteoarthritis undergoing CR-TKA using an image-free navigation system were enrolled. AP kinematics, the AP translation under manual maximum stress to the knee joint at 45° flexion, rotational kinematics, and varus-valgus laxity were evaluated using a navigation system and statistically compared between the MC and CR inserts. RESULTS: AP kinematic analysis showed that the femoral position with the CR insert was significantly anterior at a maximum extension to 45° flexion compared with the MC insert (p < 0.05). The amount of AP translation at 45° flexion with the MC insert was significantly smaller than that with the CR insert (p < 0.05). Rotational kinematics found that the tibial position at maximum extension was significantly externally rotated with the MC inserts than with the CR inserts. Varus-valgus laxity was comparable between the MC and CR inserts. CONCLUSION: The current results showed that greater mid-flexion AP stability was achieved with the MC inserts than with the CR inserts in CR-TKA. Intraoperative kinematics with the MC inserts more closely resembled those with preoperative conditions in CR-TKA. LEVEL OF EVIDENCE: III, prospective comparative study.

Intraoperative posterior movement of the tibia at 90° of flexion predicts worse postoperative flexion angles in cruciate-substituting total knee arthroplasty.

PURPOSE: To investigate the correlation between intraoperative tibiofemoral anteroposterior changes at 90° of flexion and postoperative maximum flexion angles in navigated cruciate-substituting TKA. The hypothesis of this study was that intraoperative tibiofemoral anteroposterior changes at 90° of flexion indirectly reflect posterior cruciate ligament (PCL) function and associate with postoperative maximum flexion angles. METHODS: Fifty-five consecutive patients with varus osteoarthritis treated with primary TKA were retrospectively analysed. All patients received the same type of implant, placed with an image-free navigation system. The PCL was retained, and cruciate-substituting inserts were used in all cases. The mean follow-up was 44 ± 8 months. The preoperative and postoperative kinematics were measured intraoperatively with a navigation system, and the preoperative and postoperative tibiofemoral anteroposterior positions at 90° of flexion were determined. The correlation between intraoperative anteroposterior position changes and postoperative maximum flexion angles was investigated. The correlation between the change of anteroposterior position and tibiofemoral rotational angles was also assessed. RESULTS: The intraoperative anteroposterior position change was -1.7 ± 3.4 mm (a positive value indicates tibial posterior shift). Flexion angle improvement was negatively correlated with intraoperative change of tibiofemoral anteroposterior position (R2 = 0.17, p < 0.005). Postoperative maximum flexion angles were also negatively correlated with intraoperative change of tibiofemoral anteroposterior position (R2 = 0.09, p < 0.05). The postoperative amount of tibial internal rotation was positively correlated with the preoperative amount (R2 = 0.60, p < 0.0001); however, the intraoperative anteroposterior position change was not correlated with the postoperative amount of tibial internal rotation (n.s.). CONCLUSION: A navigation system may be able to indirectly evaluate PCL function and predict the postoperative flexion angles in cruciate-substituting TKA. Intraoperative posterior movement of the tibia at 90° of flexion predicts worse postoperative flexion angles in cruciate-substituting TKA. LEVEL OF EVIDENCE: Level 3, retrospective comparative study.

Serum and nutrient deprivation increase autophagic flux in intervertebral disc annulus fibrosus cells: an in vitro experimental study.

PURPOSE: The loss of nutrient supply is a suspected contributor of intervertebral disc degeneration. However, the extent to which low nutrition affects disc annulus fibrosus (AF) cells is unknown as nutrient deprivation has mainly been investigated in disc nucleus pulposus cells. Hence, an experimental study was designed to clarify the effects of limited nutrients on disc AF cell fate, including autophagy, the process by which cells recycle their own damaged components. METHODS: Rabbit disc AF cells were cultured in different media with varying serum concentrations under 5% oxygen. Cellular responses to changes in serum and nutrient concentrations were determined by measuring proliferation and metabolic activity. Autophagic flux in AF cells was longitudinally monitored using imaging cytometry and Western blotting for LC3, HMGB1, and p62/SQSTM1. Apoptosis (TUNEL staining and cleaved caspase-3 immunodetection) and cellular senescence (senescence-associated ß-galactosidase assay and p16/INK4A immunodetection) were measured. RESULTS: Markers of apoptosis and senescence increased, while cell proliferation and metabolic activity decreased under the withdrawal of serum and of nutrients other than oxygen, confirming cellular stress. Time-dependent increases in autophagy markers, including LC3 puncta number per cell, LC3-II expression, and cytoplasmic HMGB1, were observed under conditions of reduced nutrition, while an autophagy substrate, p62/SQSTM1, decreased over time. Collectively, these findings suggest increased autophagic flux in disc AF cells under serum and nutrient deprivation. CONCLUSION: Disc AF cells exhibit distinct responses to serum and nutrient deprivation. Cellular responses include cell death and quiescence in addition to reduced proliferation and metabolic activity, as well as activation of autophagy under conditions of nutritional stress. These slides can be retrieved under Electronic Supplementary Material.

A vertical load applied towards the trunk unilaterally increases the bilateral abdominal muscle activities.

[Purpose] It is considered that evaluation of the vertical trunk function is important, because humans stand and move with two legs. To evaluate this, a novel method named Trunk Righting Test has been reported. The purpose of this study was to examine the trunk muscle activity during a TRT using electromyogram analysis. [Participants and Methods] This study included 7 healthy volunteer males. The TRT evaluated the supportability of the posture after moving 10 cm laterally from the sitting position using a hand-held dynamometer. The TRT measurements were analyzed separately at the measurement side (ipsilateral side) and at the non-measurement side (contralateral side). The measurements were obtained bilaterally, and the evaluated muscles included the rectus abdominis, internal oblique, external oblique, multifidus, and transversus abdominis. The measured value was expressed as a percentage after comparing with the value at the maximum voluntary contraction (% MVC) for standardization. The changes in the muscle activities in the sitting position and TRT were evaluated. [Results] All the muscle activities significantly increased during the TRT in contrast to that in the sitting posture. [Conclusion] The load support of the trunk on one side during the TRT was significant in all the muscles on both the sides, which increased the muscle activity, in contrast to that in the sitting position.

Stress distribution is deviated around the aperture of the femoral tunnel in the anatomic anterior cruciate ligament reconstruction.

PURPOSE: Final tunnel location in the anterior cruciate ligament (ACL) reconstruction is unpredictable due to tunnel widening and/or transposition. The mechanical stress around the tunnel aperture seems to be a major factor but is not fully investigated. The purpose of this study was to measure the stress from the ACL graft around the tunnel aperture when the ACL graft tension reaches its peak. METHODS: Six cadaveric knees were used. Single-bundle ACL reconstruction was performed using a hamstrings graft. Both femoral and tibial tunnels were created at the centre of the original ACL footprint. A 7-mm-internal-diameter aluminium cylinder with pressure sensors was placed in the femoral tunnel. Hamstrings graft with a microtension sensor was inserted. After fixation, passive extension-flexion was performed while monitoring the tunnel aperture pressure and the graft tension simultaneously. The pressure on the femoral tunnel aperture when the ACL graft tension reach its peak was compared between four directions. RESULTS: The ACL graft tension peaked (67 ± 49 N) at full extension (-5.8 ± 4.1°). Pressure at the femoral tunnel aperture was different between different directions (p < 0.01). Distal part had significantly larger pressure (1.7 ± 1.3 MPa) than the other directions (p < 0.01). Second largest pressure was carried in the anterior part (0.6 ± 0.5 MPa), followed by proximal and posterior parts (0.4 ± 0.3, 0.2 ± 0.2 MPa respectively). CONCLUSION: The stress distribution at the femoral tunnel aperture is not equal in different directions, while the distal part dominantly bears the stress from the ACL graft. Surgeons should pay close attention to the distal edge of the femoral tunnel which should be inside the anatomic ACL footprint eventually.

Tibiofemoral rotational alignment affects flexion angles in navigated posterior-stabilized total knee arthroplasty.

PURPOSE: To investigate the tibiofemoral rotational profiles during navigated posterior-stabilized (PS) total knee arthroplasty (TKA) and investigate the effect on post-operative maximum flexion angles. METHODS: Twenty-five subjects, treated with navigated PS TKA, were enrolled, and the effect of posterior cruciate ligament (PCL) resection and component implantation on tibiofemoral rotational kinematics was statistically evaluated. Then, the effect of rotational alignment changes on the post-operative maximum angles was retrospectively examined in 96 subjects using the multiple regression analysis. RESULTS: Tibial internal rotation was significantly increased in full extension (p < 0.01 and <0.001, respectively) and at 60° and 90° flexion (p < 0.05) after PCL resection, which further increased after implantation, compared with that before resection. The amount of tibial internal rotation from 90° flexion to maximum flexion was significantly decreased after PCL resection and implantation, compared with that before resection (p < 0.05). The internal changes in the rotational alignment were independent factors for the minimal improvement in the post-operative maximum flexion angles (R 2 = 0.078, p = 0.0067). CONCLUSION: PCL resection changed the tibial rotational alignment and decreased the amount of tibial internal rotation. The implantation of PS components further increased the internal rotational alignment and could not compensate for the tibiofemoral rotation. Finally, the internal changes in rotational alignment affected the improvement of the maximum flexion angles, suggesting that rotational alignment is an important factor for improving post-operative maximum flexion angles. LEVEL OF EVIDENCE: II.

Posterior Reference Position Affects Intraoperative Kinematic and Soft Tissue Balance in Navigated Posterior-Stabilized Total Knee Arthroplasty.

BACKGROUND: The importance of medial compartment stability is recognized in total knee arthroplasty (TKA). To manage the medial extension-flexion gap, the posterior reference position can be changed from conventional posterior center to posterior medial in measured resection techniques. This study aimed to compare the intraoperative soft tissue balance and rotational kinematics between the posterior medial and posterior center reference groups. METHODS: We enrolled 57 consecutive patients with varus osteoarthritis undergoing posterior-stabilized (PS) TKA using an image-free navigation system. The detailed surgical plan in both groups and intraoperative kinematics were recorded using navigation, and soft tissue balance measured with an offset-type tensor was statistically compared between groups. RESULTS: Patients were divided into the posterior center reference group (n = 32) and posterior medial reference group (n = 25). The posterior medial and posterior lateral condyles were significantly thicker in the posterior center reference group (P < .05). Although preoperative rotational kinematics were comparable between groups, the tibial rotational position was significantly more externally rotated in the posterior center reference group than in the posterior medial reference group at 45°, 60°, and 90° of flexion (P < .05). The varus angle and joint component gap were significantly smaller in the posterior medial reference group than in the posterior center reference group at 60° and 90° of flexion (P < .05). CONCLUSION: The posterior reference position affects intraoperative kinematics and soft tissue balance in navigated PS TKA. Posterior medial reference PS TKA decreases the excessive tibial external rotation during midflexion and increases the flexion stability compared with conventional posterior center reference PS TKA.

A prospective randomized comparative study to determine appropriate edoxaban administration period, to prevent deep vein thromboembolism in patients with total knee arthroplasty.

BACKGROUND: This study aimed to determine the appropriate administration duration of edoxaban 15 mg (a factor Xa inhibitor) for the prevention of deep vein thrombosis (DVT) after total knee arthroplasty (TKA). METHODS: Our study comprised 202 patients who underwent TKA (excluding bilateral TKA) at our institution between 2014 and 2015. The subjects received edoxaban 15 mg daily for 1 (n = 93) or 2 (n = 109) weeks; group assignment was random. B-mode ultrasonography was performed 7 and 14 days post-TKA for the detection of DVT. We compared the incidence of DVT between the groups and examined for side effects. RESULTS: The demographic data of the patients in the 1- and 2-week administration groups were similar at baseline. DVT incidence did not differ significantly between the groups at 1 week post-TKA. However, it was significantly lower in the 2-week administration group (n = 0) than in the 1-week administration group (n = 7; p = 0.004) at 2 weeks post-DVT. Neither group exhibited symptomatic DVT. A total of six patients withdrew during the study period because of hepatic dysfunction. CONCLUSIONS: Our results show that the administration of edoxaban 15 mg is more effective in preventing DVT after TKA when administered for 2 weeks than for 1 week.

Prothrombin time-international normalized ratio is a useful marker for edoxaban efficacy in preventing venous thromboembolism after total knee arthroplasty.

BACKGROUND: Deep vein thrombosis (DVT) is one of the main complications following total knee arthroplasty (TKA). In this study, oral administration of 15 mg edoxaban (a factor Xa inhibitor) once daily for 14 days efficiently prevented the incidence of DVT. Our hypothesis was that prothrombin time-international normalized ratio (PT-INR) on the third postoperative day could predict the incidence of DVT following TKA. METHODS: In this study, 286 subjects were enrolled and divided into two groups according to the presence or absence of DVT. Several variables [age, body mass index, postoperative D-dimer level, PT-INR, and functional recovery findings (standing)] were analysed to determine the predictors of DVT, and for DVT diagnosis, ultrasonography was performed for seven days after surgery. RESULTS: The PT-INR levels were significantly higher in the group that did not develop DVT (p = 0.01). Further analysis with logistic regression analysis and receiver operating characteristic curve was performed. The PT-INR on the third postoperative day was an independent factor of the incidence of DVT (odds ratio 0.210; p = 0.035). The cut-off PT-INR was calculated to be 1.425. CONCLUSION: PT-INR level is a useful marker in determining whether 15 mg edoxaban administration can prevent DVT after TKA. It is suggested that increment of edoxaban to control PT-INR over the cut-off point might prevent the incidence of DVT.

Factors associated with the status of meniscal tears following meniscal repair concomitant with anterior cruciate ligament reconstruction.

PURPOSE: Anterior cruciate ligament (ACL) injuries are often accompanied by meniscal tears. Meniscal repair is typically performed during ACL reconstruction. However, retear of the meniscus after repair is frequent. The purpose of this study was to analyze the factors associated with meniscal healing after meniscal repair concomitant with ACL reconstruction. MATERIALS AND METHODS: Eighty-seven meniscal repairs in 87 patients who received meniscal repair combined with ACL reconstruction and received second-look arthroscopy at a mean of postoperatively 15.7 months were examined retrospectively. The menisci were divided into three groups (complete heal, incomplete heal, and retear), and factors thought to affect the healing status of repaired menisci were analyzed using multivariate logistic regression analysis. RESULTS: Meniscal healing was judged to be complete in 49 knees (56%), incomplete in 19 knees, (22%), and retear in 19 knees (22%). There were no significant differences among the three groups in age, sex, time from injury to operation, mean Tegner activity scale, tear location, or mean postoperative anteroposterior tibial translation on KT-1000. The mean length of the tear was significantly higher in the retear group. Additionally, the proportion patients with complete tear and the proportion with postoperative positive pivot shift test were significantly higher in the retear group than in the other groups. Multivariate logistic regression analysis showed that complete tear and positive pivot shift test were associated with retear. CONCLUSIONS: These findings suggest that complete tears and residual instability are associated with retears after meniscal repair concomitant with ACL reconstruction.

Comparison Between Intra- and Extra-articular Tension of the Graft During Fixation in Anterior Cruciate Ligament Reconstruction.

PURPOSE: To evaluate the tension deprivation through the tunnels with and without preconditioning at the time of fixation, and the influences of cyclic loading and pretensioning on graft tension in anatomic single bundle anterior cruciate ligament (ACL) reconstruction using a hamstring tendon. METHODS: Nine fresh-frozen cadaveric knees underwent anatomic ACL reconstruction using hamstring grafts. Each specimen was examined to ensure that there was no severe osteoarthritic change, ligament insufficiency, or torn menisci by manual and arthroscopic evaluation. Applied graft tension was measured at the tibial tunnel outlet using a graft tensor with a load cell. Intra-articular graft tension was evaluated by using an originally developed microforce sensor, which was sutured into the graft. Both tensions were simultaneously measured just after initial tensioning under 3 different conditions: condition 1, just after initial tensioning of 20 N at 20° of knee flexion without preconditioning; condition 2, after the same initial tensioning following 5 rounds of passive cyclic flexion-extension movement; and condition 3, after the same initial tensioning following 5 minutes of static pretensioning of 20 N. RESULTS: The intra-articular tension was 12.7 ± 5.3 N in condition 1, 12.0 ± 4.8 N in condition 2, and 13.5 ± 4.8 N in condition 3. In these 3 conditions, intra-articular graft tension was significantly lower than the applied tension of around 20 N (no pretension: P = .009, cyclic pretension: P = .004, static pretension: P = .008), with no difference among the 3 conditions (P = .82). CONCLUSIONS: The intra-articular graft tension was significantly lower than the applied tension from the outside of the joint, even after cyclic loading and pretensioning. CLINICAL RELEVANCE: It is difficult to evaluate the intra-articular graft tension precisely on the basis of the extra-articular tension at time zero in ACL reconstruction.

Pseudoaneurysm of the articular branch of the descending genicular artery following double-bundle anterior cruciate ligament reconstruction.

This report describes a case of a pseudoaneurysm of the articular branch of the descending genicular artery following double-bundle anterior cruciate ligament (ACL) reconstruction. An 18-year-old male received double-bundle ACL reconstruction. During ACL reconstruction, a far anteromedial portal was created for femoral tunnel drilling. The patient presented with pulsatile swelling on the medial side of the knee on the second post-operative day. The pseudoaneurysm was diagnosed using contrast computed tomography and Doppler ultrasonography and was subsequently treated by embolization with a microcatheter. Although a vascular injury is a very rare complication of knee arthroscopy, it should be considered a possibility in patients who undergo such procedures. LEVEL OF EVIDENCE: V.

A new quantitative radiographic measurement of patella for patellar instability using the lateral plain radiograph: 'patellar width ratio'.

PURPOSE: Patellar width ratio, a new measurement of anterior-posterior patellar width, was developed using lateral radiographs. The hypothesis was that patellar width ratio would increase with increasing patellar tilt angle and that patients with patellar instability would have larger patellar width ratio compared to controls. METHODS: Fifty knees who underwent surgery for patellar instability were enrolled as Group P. The fifty knees without patellar instability were enrolled as controls (Group C). Patellar width ratio was measured using preoperative lateral radiographs. The width between proximal and distal apexes of patella was defined as A. The width between anterior and posterior margins of patella was defined as B. Patellar width ratio was defined as the ratio B/A. Patellar tilt angle was measured on preoperative computed tomography images. Values were compared between groups and their correlation examined, and a receiver operating characteristic (ROC) curve was generated to identify the threshold value. RESULTS: Mean patellar width ratio in Groups C and P was 0.54 ± 0.04 and 0.66 ± 0.11 (P < 0.01). Mean patellar tilt angle in Groups C and P was 12.8° ± 4.9° and 32.0° ± 10.3° (P < 0.01). Patellar width ratio was strongly correlated with patellar tilt angle (R = 0.83, P < 0.01). For patellar width ratio, the area under ROC curve was 0.86, and the cut-off value was 0.59 (sensitivity 76.0 %, specificity 90.0 %). CONCLUSION: Patellar width ratio in Group P was significantly larger than in Group C. Patellar width ratio would allow clinicians to evaluate patellar tilt on lateral radiographs. LEVEL OF EVIDENCE: III.

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.

Clinical outcomes and biomechanical analysis of posterolateral bundle augmentation in patients with partial anterior cruciate ligament tears.

PURPOSE: To examine the clinical and biomechanical results of posterolateral (PL) augmentation to reconstruct damaged PL bundle while preserving the less-damaged anteromedial bundle for partial anterior cruciate ligament (ACL) tears in comparison with double-bundle ACL reconstruction. METHODS: Sixteen patients who underwent PL augmentation for partial ACL tears (Group P) and 37 patients who underwent double-bundle ACL reconstructions for complete ACL tears were examined (Group D). Anterior tibial translation (ATT) was evaluated using the KT-1000 arthrometer. ATT during the Lachman test and acceleration of posterior tibial translation (APT) during the pivot shift test were evaluated using an electromagnetic measurement system (EMS). Clinical outcomes were evaluated using the Lysholm score. Second-look arthroscopy was performed 1 year after surgery. RESULTS: The mean postoperative Lysholm scores were 91.7 ± 12.2 and 94.6 ± 7.2 in Groups P and D, respectively, and there was no statistically significant difference between the two groups. The mean side-to-side difference of ATT on the KT-1000 was significantly improved in both Groups P and D. In the EMS analysis, the mean side-to-side difference of ATT and the mean APT were significantly improved in both Groups P and D. There was no significant difference in the second-look evaluation between the two groups. CONCLUSIONS: The clinical and biomechanical outcomes of PL augmentation were satisfactorily comparable to those of double-bundle ACL reconstruction. PL augmentation could be a useful treatment option for patients with partial ACL tears. LEVEL OF EVIDENCE: IV.

Factors affecting quadriceps strength recovery after anterior cruciate ligament reconstruction with hamstring autografts in athletes.

PURPOSE: Patients typically return to sports activities 6-12 months after anterior cruciate ligament (ACL) reconstruction, and quadriceps strength has been used as one of the criteria to return to sports activities. The purpose of this study is to identify the factors that affect quadriceps strength recovery after ACL reconstruction with a hamstring tendon autograft 6 months after surgery. METHODS: Isokinetic quadriceps strength at 60°/s was measured preoperatively and 6 months after surgery in 193 athletes who underwent ACL reconstruction with a hamstring tendon autograft. The quadriceps strength index was calculated by normalizing the peak torque of the involved leg with the uninvolved leg. The subjects were divided into two groups according to the quadriceps strength index 6 months after surgery: at least 85 % (n = 84) or less than 85 % (n = 109). Multivariate logistic regression analysis and a receiver operating curve analysis were performed. RESULTS: The preoperative quadriceps strength index [odds ratio (OR) 1.02; 95 % confidence interval (CI) 1.01-1.03], age (OR 0.92; 95 % CI 0.86-0.98), sex (OR 2.45; 95 % CI 1.19-5.18), and knee pain (OR 0.17; 95 % CI 0.04-0.52) were independently associated with quadriceps strength recovery. The cut-off value of the preoperative quadriceps strength index was 70.2 % to obtain at least 85 % quadriceps strength index 6 months after surgery. CONCLUSION: To achieve sufficient quadriceps strength recovery at the timing of return to sports activities following ACL reconstruction using a hamstring tendon autograft, preoperative quadriceps strength, age, sex, and knee pain should be considered. LEVEL OF EVIDENCE: III.

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.

Altered expression of SDF-1 and CXCR4 during fracture healing in diabetes mellitus.

PURPOSE: Diabetes mellitus (DM) is known to impair fracture healing. The purpose of this study was to elucidate and compare the gene expression patterns and localization of stromal cell-derived factor 1 (SDF-1) and CXC chemokine receptor 4 (CXCR4) during fracture healing of the femur in rats with and without DM. METHODS: Closed transverse fractures were created in the femurs of rats equally divided into a DM group and control group; DM was induced by streptozotocin. At post-fracture days five, seven, 11, 14, 21 and 28, total RNA was extracted from the fracture callus and mRNA expression levels of SDF-1 and CXCR4 were measured by real-time polymerase chain reaction. Localization of SDF-1 and CXCR4 proteins at the fracture site was determined by immunohistochemistry at days 21 and 28. RESULTS: SDF-1 expression was significantly lower in the DM group than in the healthy group on days 21 and 28, and showed a significant difference between days 14 and 21 in the healthy group. There was no significant difference in CXCR4 expression levels between the healthy and DM groups at any time point. On day 21 immunoreactivity of SDF-1 and CXCR4 was detected at the fracture site of the healthy group but no immunoreactivity was observed in the DM group. On day 28, immunoreactivity of SDF-1 and CXCR4 was detected at the fracture site in both groups. CONCLUSION: Gene expression and localization of SDF-1 and CXCR4 was altered during fracture healing, which may contribute to the impaired fracture healing in DM.

Relationship between trunk function evaluated using the trunk righting test and physical function in patients with knee osteoarthritis.

[Purpose] The present study was to validate the importance of the trunk function evaluated by trunk righting test (TRT) with motor function in patients with knee osteoarthritis (OA) and to show the clinical use of TRT. [Subjects and Methods] This study included 50 patients with knee osteoarthritis who underwent total knee arthroplasty in our hospital. Correlations between physical functional test, such as muscle strength, balance function, and performance and TRT were statistically evaluated. [Results] The independent factors for ipsilateral TRT were maximal isometric knee extensor strength test and ipsilateral step test. The operator and non-operator side TRT were significantly associated with TUG. [Conclusion] The results showed that the physical functions are correlated with the trunk function evaluated by TRT of patients with knee OA, suggesting that healthcare workers must take into consideration the trunk function, as well as lower extremity function to improve physical function.