Knee Stability following Posterior-Stabilized Total Knee Arthroplasty: Comparison of Medial Preserving Gap Technique and Measured Resection Technique.

Novel medial preserving gap technique (MPGT) focuses on medial compartment stability and allows lateral physiological laxity. This study aimed to compare the MPGT with the measured resection technique (MRT) to determine which provides better postoperative knee stability after posterior-stabilized total knee arthroplasty (PS-TKA). Primary PS-TKA, using either MPGT (n = 65) or MRT (n = 65), was performed in 130 patients with varus knee osteoarthritis. Postoperative knee stabilities at extension and flexion were assessed using varus-valgus stress radiographs and stress epicondylar view, respectively (at 1 month, 6 months, 1 year, and 3 years postoperatively). The distance between the femoral prosthesis and polyethylene insert was measured on each medial and lateral side, defined as the medial joint opening (MJO) and lateral joint opening (LJO), respectively. Decreasing MJO or LJO translated to increasing postoperative stability. The femoral external rotation angle was compared between the two surgical techniques; postoperative knee stability was also compared between the medial and lateral compartments, as well as the surgical techniques. A significant difference was found in the femoral external rotation angle between MPGT (4.2 ± 0.2 degrees) and MRT (3.6 ± 0.1 degrees, p < 0.01). Postoperative MJOs both at extension and flexion were significantly smaller than LJOs using MPGT and MRT at all time points (p < 0.05). MJOs and LJOs at extension using MPGT were significantly smaller than those when using MRT, at 1 and 3 years postoperatively (p < 0.05). Furthermore, MJOs at flexion using MPGT were significantly smaller than those when using MRT at 6 months, 1 year, and 3 years postoperatively (p < 0.05). MPGT provided higher postoperative medial knee stability than MRT both at extension and flexion, even at 3 years after PS-TKA. This suggests that this newly developed surgical technique is a more feasible option than MRT for the preservation of postoperative medial knee stability.

Evaluation of morphological characteristics for incomplete discoid medial meniscus with an oversized posterior segment.

BACKGROUND: A discoid medial meniscus is rare in comparison with a discoid lateral meniscus. We encountered a new type of incomplete discoid with an oversized posterior segment. Therefore, this study aimed to report cases of medial meniscus with an oversized posterior segment and analyze the morphological characteristics by comparing them to cases with a discoid medial meniscus and normal medial meniscus. METHODS: Four patients with an oversized posterior segment medial meniscus (oversize group, mean age: 25.3 ± 12.0 years) and seven patients with a discoid medial meniscus (discoid group, mean age: 34.4 ± 19.6) were identified using magnetic resonance imaging (MRI) and diagnosed by arthroscopic findings in our hospital. Fifty patients without medial meniscal injury were retrospectively selected as the normal group (normal group, mean age: 24.0 ± 11.3 years). The clinical symptoms were examined. The anteroposterior (AP) length of both the anterior and posterior segments, AP length ratio of the posterior segment to the AP length of the medial tibial plateau, and mediolateral (ML) width of the mid-body of the medial meniscus were also evaluated using MRI and compared among the three groups. RESULTS: All patients in the oversize group complained of medial knee pain during deep knee flexion. In sagittal MRI, posteriorly deviated indentations were also observed at the medial tibial plateau in all cases in the oversize group. There was a significant difference in the AP length of the posterior segment between the normal and oversize groups (14.3 ± 2.8 vs. 23.6 ± 2.8 mm, P < 0.001), whereas there was no significant difference in the AP length of the anterior segment (9.1 ± 2.1 vs. 9.5 ± 1.9 mm, P = 0.869). The ML width of the mid-body in the normal, oversize, and discoid groups was 9.3 ± 1.8, 19.9 ± 2.6, and 25.8 ± 1.9 mm, respectively (normal vs. oversize group: P < 0.001, oversize vs discoid group: P = 0.01, normal vs. discoid group: P < 0.001). CONCLUSIONS: Oversized posterior and normal anterior segments characterize this new type of incomplete discoid medial meniscus as a morphological abnormality.

Staged Bilateral Total Knee Arthroplasty in a Patient with Charcot Knees: A Case Report.

INTRODUCTION: Charcot arthropathy causes severe progressive and destructive joint disease. With the development of prostheses and surgical techniques, orthopedic surgeons have a greater opportunity to use total knee arthroplasty (TKA) to treat Charcot knee. However, consensus is lacking regarding prosthesis choice. Here, we present a case of staged bilateral TKA in a patient with bilateral Charcot knees in a different way. CASE REPORT: We report a case of a 64-year-old woman with bilateral Charcot knees. Her knee joints had become increasingly unstable with severe deformity over 1 year, and she has been unable to walk for1 month before hospitalization. We performed the first TKA of the right knee using rotating hinge prosthesis with a combination of autologous bone graft and metal tibial block augmentation; lateral release and patellar replacement were also performed. Three months after the first surgery, we performed the second TKA for her left knee using a constrained condylar prosthesis with a combination of lateral retinaculum release and patella replacement. At the 6-month follow-up, both knees were stable and in good alignment. There were no signs of loosening or fracture. The patient experienced no pain and was able to ambulate in her household using a walker. CONCLUSION: TKA using constrained condylar or rotating hinge prosthesis effectively treats Charcot knee. Surgeons must acquire both appropriate alignment and ligament stability rather than the range of motion to ensure increased longevity of the prosthesis by performing various surgical techniques. Careful follow-up is needed, but Charcot knee patients can have good outcomes with TKA.

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.

Influence of the Injury-to-Surgery Interval on the Healing Potential of Human Anterior Cruciate Ligament-Derived Cells.

BACKGROUND: Vascular CD34+ cells in anterior cruciate ligament (ACL) tissue have the potential for high proliferation and multilineage differentiation that can accelerate tendon-bone healing. While patient characteristics, such as age, can affect tendon-bone healing, the influence of elapsed time after injury on the healing process is unclear. HYPOTHESIS: Cells obtained during the early phase after injury will exhibit a greater tendon-bone healing potential compared with chronic phase counterparts when applied to an immunodeficient rat model of ACL reconstruction. STUDY DESIGN: Controlled laboratory study. METHODS: Adult human ACL-ruptured tissue was harvested from patients undergoing arthroscopic primary ACL reconstruction and classified into 2 groups based on the time elapsed between injury and surgery: (1) early group (≤3 months from injury) and (2) chronic group (>3 months from injury). In addition, 76 ten-week-old female immunodeficient rats underwent ACL reconstruction, followed by intracapsular administration of one of the following: (1) ACL-derived cells from the early group (n = 5), (2) ACL-derived cells from the chronic group (n = 5), or (3) phosphate-buffered saline (PBS) only (n = 5). During the 8 weeks after surgery, histological (weeks 2, 4, 8), immunohistochemical (week 2), radiographic (weeks 0, 2, 4, 8), and biomechanical (week 8) analyses were performed to evaluate tendon-bone healing. RESULTS: In the early group, the histological evaluation showed early healing, induction of endochondral ossification-like integration, and mature bone ingrowth. Micro-computed tomography showed that the tibial bone tunnels at week 4 and week 8 were significantly reduced in the early group compared with those in the chronic group and PBS group ( P < .05). Moreover, biomechanical tensile strength was significantly greater in the early group than in the other groups ( P < .05). An accelerated healing potential in the early group was further demonstrated by the enhancement of intrinsic angiogenesis/osteogenesis and human-derived vasculogenesis/osteogenesis. CONCLUSION: Compared with human ACL-derived cells obtained during the chronic phase, cells obtained during the early phase after injury have a greater tendon-bone healing potential when used in an immunodeficient rat model of ACL reconstruction. CLINICAL RELEVANCE: During ACL reconstruction surgery, transplanting ACL remnant tissue in the early phase after injury could accelerate and enhance tendon-bone healing.

Age-dependent healing potential of anterior cruciate ligament remnant-derived cells.

BACKGROUND: The anterior cruciate ligament (ACL) does not heal spontaneously after injury, and ACL patients of different ages respond differently to treatment. Although ACL-derived CD34-positive cells contribute to bone-tendon healing after ACL reconstruction, the relationship between the healing potential of ACL-derived cells and a patient's age is unknown. HYPOTHESIS: ACL-derived cells from young patients will have a greater effect on the maturation of bone-tendon integration in an immunodeficient rat model of ACL reconstruction compared with cells derived from older patients. STUDY DESIGN: Controlled laboratory study. METHODS: Sixty 10-week-old female immunodeficient rats underwent ACL reconstruction (using the autologous flexor digitorum longus tendon as a graft) followed by intracapsular administration of ACL-derived cells from patients aged 10 to 19 years (younger group) or patients aged 30 to 39 years (older group), or they were given phosphate-buffered saline (PBS; PBS group). Histologic, radiographic, and biomechanical examinations were performed 2 to 8 weeks after surgery. In addition, intrinsic and human cell-derived angiogenesis and osteogenesis were examined by immunohistochemistry. RESULTS: In the younger group, histologic assessment demonstrated early bone-tendon healing, which induced endochondral ossification-like integration. Micro-computed tomography showed a statistically significant reduction in the area of tibial bone tunnel in the younger group (week 4, 20.0% ± 11.2% reduction; week 8, 25.7% ± 5.6% reduction) compared with the older group (week 4, 1.8% ± 3.0% reduction; week 8, 4.0% ± 5.9% reduction) and the PBS group (week 4, -0.5% ± 3.2% reduction; week 8, 3.3% ± 5.2% reduction) (week 4, P < .05; week 8, P < .01). Failure loads during tensile testing demonstrated a significantly higher ultimate load to failure in the younger group (17.52 ± 4.01 N) compared with the older (8.05 ± 2.91 N) and PBS (7.01 ± 3.16 N) groups (P < .05), and isolectin B4 and rat osteocalcin immunostaining indicated enhanced intrinsic angiogenesis and osteogenesis in the younger group. There was no statistically significant difference in the results of radiographic and biomechanical examinations between the older and PBS groups. Double immunohistochemistry for human-specific endothelial cell and osteoblast markers demonstrated a greater ability of differentiation into endothelial cells and osteoblasts in the younger group. CONCLUSION: ACL-derived cells from younger patients enhanced early bone-tendon healing in an immunodeficient rat model of ACL reconstruction. CLINICAL RELEVANCE: Surgeons should consider a patient's age when performing ACL reconstruction with remnant preservation or ruptured tissue incorporation, as this can predict healing ability.

Parosteal osteoma of the clavicle.

Introduction. Osteoma is a benign, slowly growing, asymptomatic, osteogenic neoplasm. Osteoma of a bone other than the skull and facial bones is extremely rare. An extremely rare case of parosteal osteoma is reported. Case Presentation. A 51-year-old woman presented with a large mass in the left supraclavicular fossa. Radiographs and computed tomography revealed a well-defined, 9 × 6 cm, lobed mass in the midportion of the clavicle. Magnetic resonance imaging revealed that it had the same density as cortical bone. An open biopsy was performed to rule out malignant bone tumours, and parosteal osteoma was diagnosed. Four years after the biopsy, the patient was asymptomatic. Conclusion. A rare case of parosteal osteoma of the clavicle was described. Open biopsy is required to rule out a malignant bone tumour, even if parosteal osteoma is suspected based on the clinical course and imaging findings.