Lateral posterior tibial slope does not affect femoral but does affect tibial tunnel widening following anatomic anterior cruciate ligament reconstruction using a Bone-Patellar Tendon-Bone graft.

Background: Tunnel widening (TW) after anterior cruciate ligament (ACL) reconstruction has been a research area of interest in ACL reconstruction. In recent years, it has been noted that posterior tibial slope (PTS) affects several types of outcomes after ACL reconstruction including TW. However, the relationships between femoral and tibial TW and between PTS and TW following anatomical ACL reconstruction using a bone-patellar tendon-bone (BTB) graft are often not understood. Therefore, the purpose of this study was to retrospectively clarify the magnitude of femoral and tibial TW and the effect of PTS on TW following anatomical ACL reconstruction using a BTB graft. Methods: A total of 111 patients who underwent isolated ACL reconstructions using BTB grafts were included in this study. Femoral and tibial tunnel aperture areas were measured using three-dimensional computed tomography (3D CT) at 1 week and 1 year postoperatively, and femoral and tibial TW (%) was calculated. Lateral and medial PTS was also measured using 3D CT. Results: As compared with 1 week postoperatively, the mean tibial tunnel aperture areas increased by 30.6% ± 28.5%, and the mean femoral tunnel aperture areas increased by 28.3% ± 27.9% when measured at 1 year postoperatively. Although no significant difference was observed between femoral and tibial TW, a significant positive correlation was noted between femoral and tibial TW (r = 0.240, p = 0.011). A significant correlation was observed only between lateral PTS and tibial TW (r = 0.354, p < 0.001). There was no significant correlation between medial PTS and tibial TW, lateral PTS and femoral TW, or medial PTS and femoral TW. Conclusion: Significant positive correlation was observed between femoral and tibial TW. Steeper lateral PTS correlated with greater tibial TW; on the other hand, medial PTS did not correlate with tibial TW. Although lateral PTS affected tibial TW, it did not affect femoral TW.

Divergence in chondrogenic potential between in vitro and in vivo of adipose- and synovial-stem cells from mouse and human.

BACKGROUND: Somatic stem cell transplantation has been performed for cartilage injury, but the reparative mechanisms are still conflicting. The chondrogenic potential of stem cells are thought as promising features for cartilage therapy; however, the correlation between their potential for chondrogenesis in vitro and in vivo remains undefined. The purpose of this study was to investigate the intrinsic chondrogenic condition depends on cell types and explore an indicator to select useful stem cells for cartilage regeneration. METHODS: The chondrogenic potential of two different stem cell types derived from adipose tissue (ASCs) and synovium (SSCs) of mice and humans was assessed using bone morphogenic protein-2 (BMP2) and transforming growth factor-ß1 (TGFß1). Their in vivo chondrogenic potential was validated through transplantation into a mouse osteochondral defect model. RESULTS: All cell types showed apparent chondrogenesis under the combination of BMP2 and TGFß1 in vitro, as assessed by the formation of proteoglycan- and type 2 collagen (COL2)-rich tissues. However, our results vastly differed with those observed following single stimulation among species and cell types; apparent chondrogenesis of mouse SSCs was observed with supplementation of BMP2 or TGFß1, whereas chondrogenesis of mouse ASCs and human SSCs was observed with supplementation of BMP2 not TGFß1. Human ASCs showed no obvious chondrogenesis following single stimulation. Mouse SSCs showed the formation of hyaline-like cartilage which had less fibrous components (COL1/3) with supplementation of TGFß1. However, human cells developed COL1/3+ tissues with all treatments. Transcriptomic analysis for TGFß receptors and ligands of cells prior to chondrogenic induction did not indicate their distinct reactivity to the TGFß1 or BMP2. In the transplanted site in vivo, mouse SSCs formed hyaline-like cartilage (proteoglycan+/COL2+/COL1-/COL3-) but other cell types mainly formed COL1/3-positive fibrous tissues in line with in vitro reactivity to TGFß1. CONCLUSION: Optimal chondrogenic factors driving chondrogenesis from somatic stem cells are intrinsically distinct among cell types and species. Among them, the response to TGFß1 may possibly represent the fate of stem cells when locally transplanted into cartilage defects.

Lateral posterior tibial slope and length of the tendon within the tibial tunnel are independent factors to predict tibial tunnel widening following anatomic anterior cruciate ligament reconstruction.

PURPOSE: This study aimed to conduct a multivariate analysis to identify independent factors that predict tibial tunnel widening (TW) after anatomical anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BPTB) grafts. METHODS: In total, 103 patients who underwent ACL reconstructions using BPTB grafts were included. Tunnel aperture area was measured using three-dimensional computed tomography 1 week and 1 year postoperatively, and the tibial TW was calculated. The patients were divided into group S comprising 58 patients who had tibial TW < 30% and group L comprising 45 patients who had tibial TW > 30%, retrospectively. Using univariate analyses, age, gender, body mass index, Tegner activity scale, the time between injury and surgery, tibial tunnel location, tibial tunnel angle, medial posterior tibial slope, lateral posterior tibial slope, and length of the tendon in the tibial tunnel were compared between two groups. Multivariate regression analysis was conducted to reveal the independent risk factors for the tibial TW among preoperative demographic factors and radiographic parameters that correlated with the tibial TW in the univariate analyses. RESULTS: Compared with those at 1 week postoperatively, mean tibial tunnel aperture areas were increased by 30.3% ± 26.8% when measured at 1 year postoperatively. The lateral posterior tibial slope was significantly larger (p < 0.001), and the length of the tendon within the tibial tunnel was significantly longer in group L than that in group S (p = 0.03) in the univariate analyses. Multivariate regression analysis showed that the increase in lateral posterior tibial slope (p = 0.001) and the length of the tendon within the tibial tunnel (p = 0.03) were predictors of the tibial TW. CONCLUSIONS: This study showed that increased lateral posterior tibial slope and a longer tendinous portion within the tibial tunnel were independent factors that predicted the tibial TW following anatomical ACL reconstruction with a BPTB graft. LEVEL OF EVIDENCE: III.

Appropriate Timing for Evaluation of the Short-Term Effectiveness of Unicompartmental Knee Arthroplasty.

Satisfactory results have been achieved with unicompartmental knee arthroplasty (UKA) for the treatment of isolated unicompartmental knee disease. However, UKA is associated with a significantly higher rate of revision. There is a tendency toward early revision of UKA for persistent pain because surgeons are not aware that outcomes can spontaneously improve with time. The aim of this study was to identify the time period that patients achieved the highest clinical outcomes following UKA. In total, we examined 72 knees that underwent Oxford UKA. We evaluated the range of motion and clinical results including Knee Society Knee Score, Knee Society Function Score (KSFS), and patient-reported scores using the Knee injury and Osteoarthritis Outcome Score (KOOS) at 1, 2, and 3 years postoperatively. The extension angle showed significant recovery from 1 to 2 years postoperatively, but no significant recovery was observed between 2 and 3 years. The flexion angle at 2 years is larger than at 1 year. The KSFS at 3 years is significantly lower than that at 1 year. The KOOS subscale of activities of daily living showed no significant differences among three periods after operation. The subscales of pain, symptom, sports, and quality of life showed significant recovery from 1 to 2 years postoperatively, but no significant recovery was observed from 2 to 3 years. To evaluate the effectiveness of Oxford UKA, surgeons should obtain clinical outcomes 2 years after the operation.

Chronological Changes in Anterior Knee Stability after Anatomical Anterior Cruciate Ligament Reconstruction Using Bone-Patellar Tendon-Bone and Hamstring Grafts.

The clinical outcomes of anterior cruciate ligament (ACL) reconstruction are typically evaluated at specific time points only. This study aimed to characterize the chronological changes in anterior knee stability after anatomical ACL reconstruction and to compare the anterior knee stability achieved with bone-patellar tendon-bone (BPTB) and hamstring tendon (HT) grafts. A total of 59 patients underwent anatomical rectangular tunnel ACL reconstruction using the BPTB graft and 23 patients underwent anatomical double-bundle ACL reconstruction using the HT graft. Anterior knee stability was quantitatively assessed using the KneeLax 3 arthrometer at 6 months, 1 year, and 2 years after surgery using side-to-side differences. The values for anterior knee stability using the BPTB graft were 0.3 mm after 6 months, 0.2 mm after 1 year, and 0.2 mm after 2 years, and no significant differences were observed during the postoperative study period. Meanwhile, the values for anterior knee stability using the HT graft were -0.3 mm after 6 months, 0.5 mm after 1 year, and 1.2 mm after 2 years, and anterior knee stability decreased chronologically from 6 months up to 2 years. Regarding anterior stability, the HT graft showed significant laxity compared with the BPTB graft only after 2 years. No chronological changes in anterior stability were observed from 6 months up to 2 years after ACL reconstruction using the BPTB graft, whereas anterior laxity developed during the same period after ACL reconstruction using the HT graft. This is a Level IV, therapeutic case series study.

Iliotibial band friction syndrome after knee arthroplasty.

Iliotibial band (ITB) friction syndrome is known to be one of the main causes of lateral knee pain related to an overuse injury. In the field of knee arthroplasty, ITB traction syndrome has been reported following guided motion total knee arthroplasty, due to posterior femoral translation and internal tibial rotation during knee flexion. However, ITB friction syndrome following conventional knee arthroplasty has not been reported. This paper reports four cases of this syndrome following conventional knee arthroplasty, mainly caused by an obstruction just under the ITB. Cases 1 and 2 presented extruded cement at the femoral component's lateral side after total knee arthroplasty. Case 3 presented a highly sharp-edged bearing at the lateral compartment after bicompartmental knee arthroplasty. Case 4 presented an osteophyte at the femoral component's lateral side after total knee arthroplasty. Although none of the cases responded well to conservative treatment, ITB friction syndrome was completely relieved just after excising the obstruction. Excision of an obstruction should be considered for ITB friction syndrome caused by obstruction just under the ITB following knee arthroplasty.

Length of the Tendon within the Tibial Tunnel Affects Tibial Tunnel Widening following Anatomic Anterior Cruciate Ligament Reconstruction Using a Bone-Patellar Tendon-Bone Graft.

The purpose of this study was to retrospectively investigate the effects of variations in the length of the tendon within the tibial tunnel on tunnel widening (TW) following anatomical anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BTB) graft. In total, 68 patients who underwent isolated ACL reconstructions using BTB grafts were included in this study. The patients were divided into two groups according to the length of the tendon within the tibial tunnel: group S (n = 30; tendon length, < 10 mm) and group L (n = 38; tendon length, ≥ 10 mm). Tunnel aperture area was measured using three-dimensional computed tomography (3D CT) at 1 week and 1 year postoperatively, and tibial TW (%) was calculated. The correlation coefficient between the length of the tendon within the tibial tunnel and tibial TW was also calculated. Clinical assessment was performed 1 year postoperatively, corresponding to the period of CT assessment, which involved the evaluation of the Lysholm's score, measurement of anterior knee stability using a KneeLax3 arthrometer, and the pivot-shift test. A weak positive correlation was observed between the length of the tendon within the tibial tunnel and tibial TW (r = 0.270, p = 0.026). Mean tibial tunnel aperture area increased by 19.3 ± 17.4% and 35.8 ± 25.4% in the groups S and L, respectively. TW in the group L was significantly greater than that in the group S (p = 0.004). No significant difference was observed between the two groups in any clinical outcomes. In conclusion, a longer tendinous portion within the tibial tunnel resulted in a greater tibial TW following anatomical ACL reconstructions using a BTB graft.

Necessary Factors to Achieve Deep Flexion for Asian Populations after Oxford Unicompartmental Knee Arthroplasty.

There have been many reports on the clinical outcomes of Oxford unicompartmental knee arthroplasty (UKA); however, none have investigated the influence of flexion angle after UKA on clinical outcomes. The objective of this study was to clarify the relationship between outcomes and the postoperative maximum flexion angle and reveal the necessary factors for maximum flexion angle ≥ 140 degrees which is considered necessary for Asian populations. We categorized 212 UKA patients into the following three groups based on the postoperative maximum flexion angle: group 1 had flexion angle ≥ 140 degrees in 80 patients (38%), group 2 had 130 degrees ≤ flexion angle < 140 degrees in 80 patients (38%), and group 3 had flexion angle < 130 degrees in 52 patients (24%). Furthermore, we compared the postoperative clinical outcomes between the three groups and conducted multivariable regression analyses to assess parameters affecting the flexion angle. Postoperative Knee Society function scores for group 1 was significantly higher than for group 3. Group 1 had higher mean knee injury and osteoarthritis outcome scores (KOOS) in all subscales and significantly higher KOOS scores in the sports and quality of life subscales compared with group 2 and in all subscales compared with group 3. Multivariable logistic regression showed that preoperative flexion angle and tibial component posterior slope were associated with maximum flexion angle ≥ 140 degrees. Maximum flexion angle ≥ 140 degrees after Oxford UKA improved the clinical results, particularly for patient-reported outcomes. Furthermore, the tibial posterior slope was an important factor in achieving maximum flexion angle ≥ 140 degrees in UKA patients.

Intraoperative Tibial Anteroposterior Axis Could Not Be Replicated After Tibial Osteotomy in Total Knee Arthroplasty.

BACKGROUND: We evaluated the effect of the anteroposterior (AP) axis of the proximal tibia defined at the cutting surface using an image-free navigation system in total knee arthroplasty. METHODS: This prospective study included 68 patients (79 knees) who underwent total knee arthroplasty. The tibial AP axis was registered in the navigation system with reference to Akagi's line, connecting the middle of the posterior cruciate ligament to the medial border of the patellar tendon attachment at the tibial joint surface. After proximal tibial osteotomy, the AP axis was replicated as the AP(O) axis. We measured the difference between the AP axis defined at the joint surface and the AP(O) axis defined at the osteotomy surface. RESULTS: The AP(O) axis at the osteotomy surface internally rotated 2.0° to the AP axis at the joint surface, and the AP(O) axis outlier (difference to AP axis: >3°) occurred in 54% (43 knees). In the >3° malrotation group, internal malrotation occurred in 37% (30 knees) and external malrotation occurred in 17% (13 knees). In the outlier analysis, the left knees were significantly found in the internal outlier group. CONCLUSION: The tibial AP axis, connecting the middle of the posterior cruciate ligament to the medial border of the patellar tendon attachment defined at the tibial joint surface, could not be replicated at the tibial osteotomy surface. If the tibial components were set depending only on the AP axis defined at the osteotomy surface, the tibial components could internally rotate and have more outliers, especially in the left knees.

Intraoperative mobile-bearing movement in Oxford unicompartmental knee arthroplasty.

PURPOSE: Mobile-bearing Oxford unicompartmental knee arthroplasty has been used widely and successfully; however, there is no previous research on the intraoperative bearing movement. The purpose of this study was to characterise intraoperative bearing movement and investigate whether bearing movement relates to component positions, bearing size, intraoperative rotational kinematics and clinical results. METHODS: A trial tibial component, which was scaled every 2 mm, was used to measure the intraoperative movement of the mobile bearings. Bearing movements from 30° flexion to deep flexion were classified into two groups: 30 patients exhibited posterior bearing movement that contacted the lateral wall of the tibial component (Group W), and 37 patients exhibited posterior bearing movement, without contact, or with only transient contact, with the lateral wall (Group S). RESULTS: All mobile bearings moved posteriorly during knee flexion in the anteroposterior direction. In postoperative radiography with the knee flexed, the femoral component in Group W was significantly more laterally implanted than that in Group S. The width ratio between the bearing and tibial component in Group W was significantly greater than in Group S. There were no significant differences in other radiological measurements, intraoperative rotational kinematics or clinical results. CONCLUSION: During knee flexion, all mobile bearings moved posteriorly, and mobile bearings whose femoral components were set laterally, tended to move posteriorly while in contact with the lateral wall. However, there were no significant differences in clinical evaluation. LEVEL OF EVIDENCE: IV.

Meniscal bearing dislocation while rolling over in sleep following Oxford medial unicompartmental knee arthroplasty.

Meniscal bearing dislocation while rolling over in sleep has never been reported in Oxford unicompartmental knee arthroplasty (UKA). This study reports two cases of meniscal bearing dislocation into the intercondylar ridge while rolling over in sleep. In the case of one patient, closed reduction of the bearing was performed, and the use of a knee brace was effective in preventing re-dislocation. In the second patient, closed reduction was possible; however, bearing dislocation was repeated. Therefore, revision surgery was performed by replacing the tibial component and using a thicker bearing. The common features in dislocation during rolling over while sleeping in both cases were dislocation into the intercondylar ridge, the combination of small femur and AA-size tibia components, and osteonecrosis. As determined by intraoperative testing, valgus position of the knee while rolling over in sleep could induce bearing dislocation into the intercondylar ridge. LEVEL OF EVIDENCE: Retrospective case series, Level IV.

The relationship between anteroposterior stability and medial-lateral stability of the bi-cruciate stabilized total knee arthroplasty.

BACKGROUND: Acquisition of appropriate anteroposterior (AP) stability depends on the prosthetic design and intraoperative soft tissue handling. A bi-cruciate stabilized (BCS) total knee arthroplasty (TKA) has a two cam-post mechanism, which substitutes for the anterior cruciate ligament and posterior cruciate ligament (PCL). Therefore, appropriate AP stability is expected. Because the PCL is sacrificed during BCS TKA, medial stability and lateral stability are thought to be important factors to determine AP stability. However, no previous study has reported AP stability after BCS TKA and the relationship between AP and medial-lateral stability. METHODS: AP stability was measured using a navigation system intraoperatively and the KT 2000 device postoperatively. Intraoperative joint laxity of the medial and lateral compartments was evaluated separately using a compartment-specific ligament tensioner. The relationship between AP stability and medial-lateral laxity was assessed. RESULTS: Intraoperative AP translation at 30° and 90° knee flexion angles was 7.7 ±â€¯3.1 mm and 5.9 ±â€¯2.0 mm, respectively. Postoperative AP translation at 30° was 5.9 ±â€¯1.7 mm. AP translation correlated positively with medial joint laxity at 30° (R = 0.29) and 90° (R = 0.40). The intraoperative and postoperative AP translations at 30° flexion had a positive relationship (R = 0.61). CONCLUSION: AP stability of the BCS TKA had a positive relationship with intraoperative medial stability. Therefore, surgical soft tissue handling focusing on medial stability is also appropriate for AP stability of BCS TKA. Additionally, intraoperative AP translation turned out to be a predictive indicator for postoperative knee AP stability at 30° flexion.

Surgical timing of anterior cruciate ligament reconstruction to prevent associated meniscal and cartilage lesions.

BACKGROUND: The purpose of this study was to analyze the association between the prevalence of meniscal and chondral lesions and the timing of surgery in patients undergoing primary anterior cruciate ligament (ACL) reconstruction to determine a safe time for surgery. METHODS: This retrospective study involved 226 patients (91 females and 135 males; median age, 29 years) undergoing primary ACL reconstruction. Time interval from ACL injury to surgery (median, 4 months; range, 1-420 months) and concomitant meniscal and cartilage lesions in ACL reconstruction were reviewed. Receiver operating characteristic (ROC) curve analysis was used to determine the precise threshold interval to surgery to prevent meniscal or cartilage lesions. The risk of lesion occurrence after each cutoff period was determined using odds ratio (OR). RESULTS: The incidences of medial meniscus (MM), lateral meniscus (LM), and cartilage lesions were 43.8%, 32.7%, and 27.4%, respectively. ROC analysis revealed that patients who waited for more than 6, 4, and 5 months for ACL reconstruction had a significantly greater risk of associated MM, LM, and chondral lesions, respectively. Patients who underwent ACL reconstruction ≥7 months after injury had OR of 4.1 (p < 0.001) for the presence of MM lesion as compared with those who underwent reconstruction within 6 months. Similarly, patients who underwent ACL reconstruction ≥5 months after injury had OR of 1.9 (p = 0.023) for the presence of LM lesion as compared with those who underwent reconstruction within 4 months, and patients who underwent ACL reconstruction ≥6 months after injury had OR of 2.9 (p < 0.001) for chondral lesion as compared with those who underwent reconstruction within 6 months. CONCLUSION: ACL reconstruction should be performed within approximately 6 months after the injury to prevent associated meniscal or chondral lesions.