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Purpose: Balancing the gap is essential in total knee arthroplasty (TKA). The purpose of this study was to quantify the influence of patellar position on femoro-tibial joint load in TKA. We hypothesized that resetting of the patella increased medial joint load and decreased lateral joint load., Methods: Our original tensor system was used during posterior-stabilized (PS) and cruciate-retaining (CR) total knee arthroplasty (TKA) using medial para-patellar approach (MPP) or sub-vastus approach (SV)., Results: In PS-TKA, by resetting the patella, the ratios between medial and lateral compartments were not changed in both extension and flexion position using MPP and were significantly changed in flexion position using SV. In CR-TKA, by resetting the patella, the load of the lateral component decreased and the ratios between medial and lateral compartments were changed significantly in both extension and flexion position using SV., Conclusion: It is important to be aware that, when performing CR-KA, the load of the lateral compartment will decrease by resetting the patella using SV.

An original tensor system was developed to directly measure the load between femoral trial component and tibial cut surface in vivo in both patella everted and reset positions during total knee arthroplasty (TKA). We used this system during posterior-stabilized (PS) and cruciate-retaining (CR) TKA. In PS-TKA, there was no significant difference between the loads in extension in patella everted position and reset position. In flexion, however, there was significant increase of load in patella reset position compared to in everted position. In CR-TKA, there was no significant difference between the loads in patella everted position and in patella reset position in either extension or flexion. It was found that the effect of patella position on joint gap load was different between PS-TKA and CR-TKA. It is important to be aware that, when performing PS-KA, the load in flexion gap will increase, in other words, flexion gap distance will decrease by resetting the patella.

We describe a case of popliteofibular ligament (PFL) injury, successfully treated with a new anatomic reconstruction technique looping the biceps femoris tendon (BT). The anterior half of the BT was split longitudinally from the fibular insertion, cut at the proximal end and left attached at the insertion. The proximal end of the BT was looped back in a slit made in the popliteal tendon (PT) at the original anatomical insertion site of the PFL, and passed through the tunnel from the posterior and the baseball suture was tightened on the anterior cortex of fibular head.

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) was used for the measurement of relative proteoglycan depletion of articular cartilage in the patellofemoral (PF) joint following a proprietary protocol, which was compared with the X-ray images, proton density weighted MR images (PDWI) and arthroscopic findings. The study examined 30 knees. The ages ranged from 16 to 74 (average 40.3) years. The Gd-DTPA(2-)containing contrast medium was used in a single dose. The subjects were made to exercise the knee joint for 10 min; and MR images were taken 2 h after intravenous injection of contrast medium. T1-calculated images were produced and the region of interest (ROI) was set as follows. (1) ROI1: entire articular cartilage in a slice through the center of the patella. (2) ROI2: low signal region in T1-calculated images, which were set in a blind fashion by two observers. (3) ROI3: articular cartilage on one side that includes ROI2 where low signal region were detected (medial or lateral). ROI3 was set to examine the contrast of ROI2 with surrounding articular cartilage. The average T1 values of ROI1 was 393.5+/-33.6 ms for radiographic grade 0 and 361.3+/-11.1 ms for grade I, which showed a significant difference (P=0.036). The T1 value of ROI2 was 351.6+/-28.2 ms for grade I, 361.9+/-38.3 ms for grade II, 362.1+/-67.7 ms for grade III, and 297.8+/-54.1 ms for grade IV according to arthroscopic Outerbridge classification. All cases, that demonstrated decrease of T1 values on dGEMRIC (ROI2), showed abnormal arthroscopic or direct viewing findings. The ratio (ROI3/ROI2) in cases of only slight damage classified as Outerbridge grade I (6 cases) was an average of 1.04+/-0.02 and was 1.0 or greater in all cases, thereby indicating well-defined contrast with the surrounding cartilage. The diagnosis of damage in articular cartilage was possible in all 16 cases with radiographic K-L grade I on dGEMRIC, while the intensity changes were not found in 10 of 16 cases on PDWI. The dGEMRIC with a single-dose would be useful on a diagnosis of the area demonstrating early relative proteoglycan depletion in the articular cartilage of the PF joint prior to any discernible changes in the subchondral bone on X-ray images and exceeds to plain MR images for examining deterioration of articular cartilage.