Anterior tibial curved cortex is a reliable landmark for tibial rotational alignment in total knee arthroplasty.

BACKGROUND: Rotational alignment of the tibial component is important for long-term success of total knee arthroplasty (TKA). This study aimed to compare five axes in normal and osteoarthritic (OA) knees to determine a reliable landmark for tibial rotational alignment in TKA. METHODS: One hundred twenty patients with OA knees and 40 with normal knees were included. The angle between a line perpendicular to the surgical transepicondylar axis and each of five axes were measured on preoperative computed tomography. The five axes were as follows: a line from the center of the posterior cruciate ligament (PCL) to the medial border of the patellar tendon (PCL-PT), medial border of the tibial tuberosity (PCL-TT1), medial one-third of the tibial tuberosity (PCL-TT2), and apex of the tibial tuberosity (PCL-TT3), as well as the anteroposterior axis of the tibial prosthesis along the anterior tibial curved cortex (ATCC). RESULTS: For all five axes tested, the mean angles were smaller in OA knees than in normal knees. In normal knees, the angle of the ATCC axis had the smallest mean value and narrowest range (1.6° ± 2.8°; range, -1.7°-7.7°). In OA knees, the mean angle of the ATCC axis (0.8° ± 2.7°; range, -7.9°-9.2°) was larger than that of the PCL-TT1 axis (0.3° ± 5.5°; range, -19.7°-10.6°) (P = 0.461), while the angle of the ATCC axis had the smallest SD and narrowest range. CONCLUSION: The ATCC was found to be the most reliable and useful anatomical landmark for tibial rotational alignment in TKA.

Different intraoperative kinematics with comparable clinical outcomes of ultracongruent and posterior stabilized mobile-bearing total knee arthroplasty.

PURPOSE: There remains no consensus as to whether mobile total knee arthroplasty (TKA) should use a posterior cruciate ligament-sacrificing ultracongruent (UC) or a posterior cruciate ligament-substituting posterior stabilized (PS) prosthesis. The purpose of this study was to assess intraoperative kinematics and clinical outcomes of UC and PS rotating platform mobile-bearing TKA. METHODS: In this randomized controlled study, mobile UC TKA prostheses (n = 45) were compared with mobile PS TKA prostheses (n = 45) with regard to intraoperative kinematics and clinical outcomes. The passive kinematic study using intraoperative navigation system included anterior/posterior translation, varus/valgus alignment and rotation of femur during flexion. The patients were clinically and radiographically evaluated over a 3-year follow-up. RESULTS: Paradoxical anterior translation of the femur was 10.8 ± 5.2 mm in the UC knee from 0° to 82° of knee flexion and 8.7 ± 3.0 mm in the PS knee from 0° to 70° of knee flexion (p = 0.027). Paradoxical internal rotation of the femur was 5.8° in the UC knees and 9.9° in the PS knees (p = 0.003). But, there was no significant difference between the groups in regard to the coronal alignment. There was no significant difference in the range of motion, KS knee scores, KS function scores, and WOMAC index scores. CONCLUSIONS: Despite different intraoperative kinematics between mobile UC and mobile PS TKA, neither design reproduced physiologic knee kinematics and there was no difference in clinical outcomes between the two groups. The clinical relevance of the study is that despite different intraoperative kinematics, UC design can be a considerable alternative to PS design in mobile-bearing TKA in respect of clinical outcomes. LEVEL OF EVIDENCE: II.

Revision total knee arthroplasty with varus-valgus constrained prosthesis versus posterior stabilized prosthesis.

PURPOSE: The aims of this retrospective study were to provide the basis for the choice of prosthesis in revision total knee arthroplasty (TKA) and to evaluate the outcome with varus-valgus constrained prosthesis compared with posterior stabilized (PS) prosthesis. METHODS: One hundred and five patients (121 knees) received revision TKA; of which thirty-seven patients (42 knees) received PS prosthesis and sixty-eight patients (79 knees) received varus-valgus constrained prosthesis. The mean follow-up duration was 64.8 ± 31.5 months and 63.2 ± 28.1 months in the PS and varus-valgus constrained groups, respectively. The criterion of prosthesis choice was a subjective laxity assessed by the surgeon intraoperatively. A multivariate analysis was performed to evaluate the preoperative factors in the choice of the prosthesis. RESULTS: The grade of femoral bone defect was the only factor that affected the choice of prosthesis. Clinical results improved significantly in both groups after surgery. There were no significant differences in clinical results between the two groups. Complication rates were 9.5 % in the PS group and 10.1 % in the varus-valgus constrained group, and the Kaplan-Meier survivorship analysis revealed 8-year component survival rates of 83.1 and 93.0 % in the PS and varus-valgus constrained groups, respectively. CONCLUSIONS: Femoral bone defect is an important factor to be considered in the choice of prosthesis for revision TKA. The varus-valgus constrained prosthesis showed an outcome similar to that of the PS prosthesis. For clinical relevance, varus-valgus constrained prosthesis is recommended in revision TKA when the PS prosthesis seems unsuitable for the management of instability. LEVEL OF EVIDENCE: III.

Preservation of the posterior cruciate ligament is not helpful in highly conforming mobile-bearing total knee arthroplasty: a randomized controlled study.

PURPOSE: The purpose of this study is to investigate whether the preservation of the posterior cruciate ligament (PCL) can be helpful for improving kinematics and clinical outcome in highly conforming mobile-bearing total knee arthroplasty (TKA). METHODS: Ninety osteoarthritic knees were randomly allocated to either the PCL-preserving group or the PCL-sacrificing group. Passive kinematics was recorded with a navigation system immediately after implantation. Three parameters (anterior/posterior translation, varus/valgus rotation, and internal/external rotation) were analysed from 0° to 120° flexion. RESULTS: The PCL-preserving group (42 knees) had more varus rotation over 90° flexion (p < 0.05) and more anterior translation of the femur in all ranges of flexion (p < 0.05) than those in the PCL-sacrificing group (44 knees). There was no difference in the internal/external rotation (p > 0.05). The range of motion, functional scores, and radiographic results did not significantly differ between the two groups at the final follow-up. Three knees in the PCL-preserving group were revised: two presented with instability caused by traumatic attenuation of the PCL and one with subluxation of the insert due to a tight PCL. CONCLUSION: The preservation of the PCL was not helpful for improving kinematics and clinical outcome in highly conforming mobile-bearing TKA.

Intraoperative correlation analysis between tunnel position and translational and rotational stability in single- and double-bundle anterior cruciate ligament reconstruction.

PURPOSE: To determine the relation between the tunnel positions and the kinematic improvement of the knee joint after single-bundle (SB) and double-bundle (DB) anterior cruciate ligament (ACL) reconstructions. METHODS: The study included 42 patients who underwent either SB (n = 21) or DB (n = 21) ACL reconstruction using hamstring tendon autograft. Anterior tibial translation and rotational laxity were measured by a navigation system before and after graft fixation. Three-dimensional computed tomography measurement was conducted for evaluation of tunnel placements. Regression analysis was carried out to determine the association between the postoperative kinematic change and the tunnel position. RESULTS: The average tunnel location was mostly different between the SB and posterolateral bundle (PLB) tunnels, as well as between the anteromedial bundle (AMB) and PLB tunnels of DB ACL reconstructions, whereas the SB and AMB tunnels were similar in the tibial mediolateral and femoral deep-shallow positions. A regression curve showed that the PLB femoral tunnel position was correlated with rotation whereas both the SB and AMB femoral tunnel locations were mostly correlated with anterior tibial translation. CONCLUSIONS: The PLB tunnel location in DB ACL reconstruction had a considerable effect on rotational laxity, whereas the SB and AMB tunnel locations mostly influenced anterior tibial translation. LEVEL OF EVIDENCE: Level III, case-control study.

Distraction arthrodesis with intramedullary nail and mixed bone grafting after failed infected total knee arthroplasty.

PURPOSE: The purpose of this study was to determine the success rate of the distraction arthrodesis, which was attempted to maintain the limb length during arthrodesis using an intramedullary nail and mixed bone grafting, in terms of the eradication of infection, solid union, and functional outcome. The hypothesis was that distraction arthrodesis would be successful in union and elimination of infection with minimal limb shortening and a satisfactory functional outcome despite large bone defects. METHODS: Eight patients were managed by arthrodesis using a Huckstep intramedullary nail and massive corticocancellous bone chip grafts from autologous iliac bone and deep-frozen femoral head allografts were included in the study. The mean age of the patients was 65.5 ± 7.1 years, and the follow-up duration was 52.1 ± 21.3 months. A mean of 5.3 ± 1.3 surgical procedures had been performed before arthrodesis. The mean longest and shortest distances of the bone defect were 58.6 ± 10.3 and 34.6 ± 7.0 mm, respectively. RESULTS: Radiological union was obtained in all cases at a mean of 9.9 ± 1.9 months. The mean postoperative limb shortening was 11.0 ± 7.3 mm when compared to the contralateral knee. The mean Knee Society score was 59.9 ± 9.2, and the function score was 38.8 ± 13.3. No additional procedures were required for any of the patients. CONCLUSION: Distraction arthrodesis of infected knees following total knee arthroplasty demonstrated union and eradication of infection in all patients and a large tibiofemoral gap due to the severe bone defect could be managed with massive bone chip grafts. This method of arthrodesis would be a reliable and an effective method for failed total knee arthroplasty when two-staged reimplantation fails or is not attainable.

Comparison of anterior and rotatory laxity using navigation between single- and double-bundle ACL reconstruction: prospective randomized trial.

PURPOSE: To prospectively assess the anterior tibial translation and rotational kinematics of the knee joint as well as the clinical outcome after single-bundle (SB) and double-bundle (DB) anterior cruciate ligament (ACL) reconstruction. METHODS: Forty-two patients randomly underwent single-bundle (Group SB, n = 21) or double-bundle (Group DB, n = 21) ACL reconstruction using hamstring tendon autografts. Anterior tibial translation and rotatory laxity were measured prior to and after fixation of the graft during reconstruction under the guidance of a navigation system. Clinical outcome measurements included the evaluation of the joint stability and functional status. RESULTS: Anterior tibial translation and rotatory laxity were improved significantly at all degrees of knee flexion in both groups. The postoperative total rotation (sum of internal and external rotation) at 30° and 60° (26.6° vs. 24.0°; 28.7° vs. 25.1°) as well as postoperative change in external rotation at 60° (-1.4° vs. -4.6°), and a change in total rotation at 30° and 60° (-7.0° vs. -11.5°; -6.1° vs. -8.9°) differed between the two groups, with better stability in the DB group. At 2 years follow-up, IKDC subjective satisfaction score was significantly different between two groups (70.9 vs. 79.6), while manual and instrumented laxity, pivot shift tests, modified Lysholm score, Tegner activity score, thigh muscle strengths were not different. Correlation analysis showed little correlations between anterior laxity tests at follow-up, and the kinematic variables measured by navigation during surgery while pivot shift test, IKDC subjective satisfaction score, modified Lysholm score, and Tegner activity score were mainly correlated with navigation-measured rotations in both groups. CONCLUSIONS: The kinematic tests in this study found evidence suggesting that the DB ACL reconstruction improved rotatory laxity better than the SB ACL reconstruction at 30° and 60° of flexion, but there was no difference in functional outcome at 2 years follow-up between SB and DB groups. LEVEL OF EVIDENCE: Prospective comparative study, Level II.

Synovium-derived mesenchymal stem cells encapsulated in a novel injectable gel can repair osteochondral defects in a rabbit model.

We developed a novel injectable type I collagen/hyaluronic acid/fibrinogen (COL/HA/FG) composite gel that encapsulated synovium-derived mesenchymal stem cells (SDSCs) for the repair of damaged articular cartilage. We first analyzed the suitability of the composite gel as a three-dimensional injectable cell carrier in vitro. In an in vivo rabbit model, the COL/HA/FG composite gel displayed the potential to regenerate and repair osteochondral defects in the knee. Culture of the SDSCs encapsulated COL/HA/FG composite gel in a chondrogenic medium resulted in high viability of the SDSCs and high expressions of type II collagen, aggrecan, and sox 9 mRNA. Moreover, glycosaminoglycans and type II collagen were accumulated within the extracellular matrix. In the animal model, the SDSCs encapsulated COL/HA/FG composite gel produced a hyaline-like cartilage construct. Twenty-four weeks after transplantation, the defects had been repaired with hyaline cartilage-like tissue that was densely stained by safranin-O and immunostained by a type II collagen antibody. This data suggest that the SDSC-encapsulated COL/HA/FG composite gel can be a good therapeutic candidate/strategy for repairing of damaged articular cartilage.