[Short-term effectiveness of novel computer navigation system assisted total knee arthroplasty]

Objective

To investigate the short-term effectiveness of novel computer navigation system (Knee 3 software; Brainlab, Germany) assisted total knee arthroplasty (TKA).

Methods

Between July 2020 and December 2020, 19 patients underwent unilateral TKA assisted with Knee 3 software. There were 4 males and 15 females. The mean age was 66.3 years (range, 52-79 years). Eighteen patients were diagnosed with osteoarthritis and 1 patient with rheumatoid arthritis. Sixteen patients had varus knees and 3 patients had valgus knees. Preoperative Western Ontario and McMaster University Osteoarthritis Index (WOMAC) pain, stiffness, function, and total scores were 12.4±3.4, 2 (1, 4), 22 (18, 29), and 37 (29, 43), respectively. Intraoperatively, the medial and lateral gaps in knee extension and in 90° of knee flexion were recorded. The operation time, intraoperative blood loss, blood transfusion, and complications were recorded. The hip-knee-ankle angle (HKA), lateral distal femoral angle, and medial proximal tibial angle were measured to evaluate lower limb alignment and prostheses's alignment using X-ray films at 6 weeks after operation. Patient's satisfaction rate and WOMAC pain, stiffness, function, and total scores were investigated.

Results

Eighteen patients (94.7%) had medial- lateral gap balancing in knee extension, 18 patients (94.7%) had medial-lateral gap balancing in 90° of knee flexion, 19 patients (100%) had medial gap balancing between knee extension and 90° of knee flexion, and 18 patients (94.7%) had lateral gap balancing between knee extension and 90° of knee flexion. The mean operation time was 126 minutes (range, 100-200 minutes). The mean intraoperative blood loss was 205 mL (range, 100-400 mL). Patients were followed up 4-8 months, with an average of 6.2 months. Postoperative complications included 1 deep vein thrombosis of lower extremities and 1 cerebral infarction. X-ray films showed that the mean HKA, lateral distal femoral angle, and medial proximal tibial angle were 179.8° (range, 178°-182°), 83.5° (range, 80°-87°), and 89.5° (range, 87°-93°), respectively. At last follow-up, WOMAC pain, stiffness, function, and total scores were 3.6±1.9, 0 (0, 2), 4 (2, 6), and 9 (5, 10), respectively, which improved when compared with preoperative scores ( P<0.05). Twelve patients were very satisfied with the operation results and 7 patients were satisfied with the operation results. The overall satisfaction rate was 100%.

Conclusion

Knee 3 software can help to obtain good gap balancing and optimal lower limb alignment, with high patient's satisfaction and good short-term effecectiveness.

Insufficient lateral joint laxity after bicruciate-retaining total knee arthroplasty potentially influences kinematics during flexion: A biomechanical cadaveric study

BACKGROUND

Soft tissue balancing in bicruciate-retaining (BCR) total knee arthroplasty (TKA) is a challenge that must be overcome to achieve excellent clinical outcomes. However, the optimal degree of joint laxity has yet to be clarified. This cadaveric study sought to examine joint laxity after BCR TKA using a navigation system.

METHODS

Knee joint laxity was quantified using an image-free navigation system in 8 intact fresh frozen cadavers under three conditions: the native knee, BCR TKA knee, and BCR TKA knee after anterior cruciate ligament resection. Rotational kinematics in the BCR TKA knee during flexion were compared according to whether joint laxity was increased or decreased.

RESULTS

Knee joint laxity after BCR TKA under varus-valgus movement, anterior translation, and internal-external rotation loadings was similar to that of the native knee. However, lateral joint laxity was decreased during flexion in some cases. BCR TKA-treated knees with decreased lateral joint laxity at 90° of flexion demonstrated more limited tibial internal rotation in deep flexion than the native knee (p < 0.05). The loss of internal rotation in deep flexion was partly recovered by using a lateral insert with a posterior slope of +3°.

CONCLUSIONS

Restoring optimal joint laxity was not always straightforward in BCR TKA if the 4 ligaments were preserved. Lateral joint laxity was potentially decreased in BCR TKA and may result in kinematic conflict during flexion. Surgeons should be aware of the need to achieve sufficient lateral joint laxity in this type of BCR TKA.

Native rotational knee kinematics are lost in bicruciate-retaining total knee arthroplasty when the tibial component is replaced

PURPOSE

To compare the kinematics between native knees and knees that have undergone bicruciate-retaining (BCR) total knee arthroplasty (TKA) with cruciate-retaining (CR) TKA converted from BCR TKA in the same whole-body cadaveric specimen using a navigation system and, if differences exist, to investigate the point at which normal kinematics are lost during the procedure.

METHODS

The rotational kinematics throughout passive flexion of the native knee and of knees after meniscectomy, femoral replacement, BCR TKA, or CR TKA were assessed in nine fresh frozen cadavers using an image-free navigation system.

RESULTS

The rotational kinematic pattern of a knee after BCR TKA was different from that of a native knee, especially in the early flexion phase, and was similar to that after CR TKA. Screw-home movement was not observed after BCR TKA, but still occurred after meniscectomy or femoral replacement with intact cruciate ligaments and an intact tibial articular surface.

CONCLUSION

The rotational kinematics of the native knee are not always preserved after BCR TKA. Native rotational kinematics are preserved after meniscectomy and femoral replacement, but are lost after tibial replacement in BCR TKA. Surgeons should pay close attention to maintain the anteroposterior stabilizing function of the ACL in BCR TKA, rather than to restore the native rotational kinematics.

The usefulness of wide excision assisted by a computer navigation system and reconstruction using a frozen bone autograft for malignant acetabular bone tumors: a report of two cases

Background

Difficult resection of tumors from regions with complex local anatomy, such as the pelvis and sacrum, is likely to result in inadequate surgical margins (intralesional or marginal); this is because three-dimensional osteotomy is difficult particularly around the acetabulum. Additionally, removal of the joint makes reconstruction very difficult; thus, retention of good function also becomes difficult. In musculoskeletal oncology, computer navigation systems are still not widely used to prevent tumor-positive margins. We performed wide excision with guidance from a computer navigation system and reconstruction using frozen bone autografts for malignant pelvic bone tumors in two patients, and we obtained excellent functional and oncological outcomes. Here we present these patients and discuss our approach.

Case presentation

Case 1: A 12-year-old girl presented with Ewing sarcoma of the left pelvis (PI-II). We performed wide excision assisted by a computer navigation system with the osteotomy of the load surface of acetabulum and reconstruction using a frozen bone autograft. At the final follow-up, she showed excellent function and was alive without the disease. Moreover, she did not have osteoarthritis of the left hip joint.

Case 2: A 71-year-old woman presented with dedifferentiated chondrosarcoma of the right pelvis (PII-III). We performed wide excision assisted by a computer navigation system with osteotomy avoiding load surface of the acetabulum and reconstruction using a frozen bone autograft; there was no tumor at the load surface. At the final follow-up, she showed good function, was alive without the disease, and did not have osteoarthritis of the left hip joint.

Conclusions

Wide excision assisted by a computer navigation system and reconstruction using a frozen bone autograft are very useful for the management/treatment of extremely difficult cases such as malignant pelvic bone tumors, particularly those including the acetabulum.

Changes in sagittal component alignment alters patellar kinematics in TKA: an in vitro study

PURPOSE

Patellar maltracking due to incorrect component alignment is considered as a main reason for anterior knee pain after total knee arthroplasty (TKA). In contrast to coronal and axial component placement, the influence of sagittal component alignment on patellar kinematics has not been investigated so far.

METHODS

In ten lower cadaveric limbs, TKAs were implanted using a commercial computer navigation system. In six knees, the femoral component was aligned in 5° and in four knees in 0° of flexion, respectively. Patellar kinematics were registered by means of a computer navigation system using an additional patella tracking array and correlated with femoral and tibial sagittal component alignment.

RESULTS

Sagittal component alignment significantly altered patellar mediolateral shift (p < 0.05). In contrast, patellar epicondylar distance, rotation and tilt were not significantly influenced.

CONCLUSIONS

Sagittal component alignment in TKA has a major impact on patellar kinematics and should therefore be considered while addressing tibiofemoral kinematics intraoperatively.