Materials and Methods: The institution’s prospective database of unicompartmental knee replacements was reviewed for all Oxford Phase III Unicompartmental Knee Replacement (Biomet, UK) undertaken from January 2004 to July 2007. This identified a total of 645 procedures undertaken. We included all cases where there was pre-operative skyline radiographs and American Knee Scores, Oxford Knee Score and SF-12 data, in addition to skyline radiographs, OKS and SF-12 data with a minimum of 2 years follow-up. All patients without this baseline and follow-up data were excluded. This provided a total of 196 knees (162 patients)

Using Altman’s nomogram, the sample size was calculated to be 85 for a power of 90%, with an α significance level of 0.05.

Using this database, digital radiographs were assessed using the institution’s PACS system. Pre-operative and follow-up skyline radiographs following Jones et al’s (1993) patellofemoral scoring system were examined by four assessors utilising Jones’ patellofemoral scoring system. In addition, in cases where patellofemoral joint changes were evident, each assessor acknowledged whether this involved the medial, lateral or bilateral aspects of the patellofemoral joint.

Intra-observer reliability was made comparing the four assessors.

Statistical analysis was performed, using the Statistical Package for the Social Sciences (SPSS) 16.0 for Windows (SPSS Inc, Chicago, Illinois).

In order to determine whether changes in patellofemoral joint status related to patients function or quality of life, the difference in OKS and SF-12 from pre-operative to the follow-up period was assessed.

Results: There was a statistically significant progression of patellofemoral osteoarthritis as found on the preoperative and postoperative radiographs (p< 0.01, Mann Whitney), there was a correlation between a low OKS and Jones patellofemoral score (P< 0.05, Mann-Whitney). However, there was no correlation between the site of patellofemoral involvement and outcome scores.

Conclusion: Due consideration should be taken when offering medial unicompartmental knee replacement to patients with patellofemoral involvement and this is independent of the site of patellofemoral involvement.

Introduction To acquire high flexion has been a current topic in TKA. However, there is concern about the trade-off between high flexion and safety. The purpose of this study was to determine the factors contributing to the high rate of aseptic loosening in femoral components of LPS-flex TKAs that we experienced.

Materials and Methods: From March 2003 to September 2004, 72 consecutive TKA were performed in 47 osteoarthritic patients by a single surgeon. The high-flex design fixed total knee prostheses (NexGen LPS-Flex) were used in all knees. The weight-bearing high flexion activities such as squatting were permitted as tolerable. We retrospectively analyzed the clinical and radiological outcome of this case series.

Results: At a mean of 32 months (range, 30 to 48 months), 27 (38%) cases had shown the radiological findings of aseptic loosening around the femoral components and fifteen (21%) cases have been revised for the progression of component loosening and pain. Postoperatively, the average maximal flexion was 136º in the loosening group, which was higher than 125º in the no-loosening group (P=0.022). The percentage of patients who could squat, kneel or sit cross-legged postoperatively was greater in the loosening group (85% versus 44%) (P=0.001). The femoral component demonstrated movement into flexion, from a mean of 4° to a mean of 7° (γ angle) in the loosening group and not in the no-loosening group.

Conclusion: The high-flex implant allowed for greater range of motion and high-flexion activities, and however, showed high rate of early femoral component loosening, which was associated with weight-bearing high-flexion activities.

Primary total knee arthroplasty is associated with considerable blood loss, and allergenic blood transfusions are frequently necessary. Because of the cost and risks of allogenic blood transfusions, the autologous drainage blood reinfusion technique has been developed as an alternative. A number of studies have compared reinfusion techniques with standard suction drainage, but few reports compared with no drain use. We analyzed early results after primary total knee arthroplasty using autologous drainage blood reinfusion and no drain.

We selected 30 patients who underwent primary total knee arthroplasty using no drain between November 2005 and March 2006 and matched for age and gender with 30 patients who underwent primary total knee arthroplasty using autologous drainage blood reinfusion technique between January 2003 and October 2005. All operations were done under pneumatic tourniquet and meticulous hemostasis was performed after deflation of the tourniquet. We have retrospectively reviewed the preoperative data (age, gender, body mass index, diagnosis, history of the knee surgery, infection and anticoagulant therapy, and medical cormorbidities) and the postoperative data (hemoglobin, hematocrit and platelet during hospitalization, the amount of allogenic blood transfusion and narcotics, complications, rehabilitation process, and clinical scores).

All preoperative and postoperative variables except the postoperative second and seventh days hemoglobin and 2nd day hematocrit showed no significant differences between two groups. The hemoglobin and hematocrit also showed no significant differences at the postoperative fourteenth day.

The autologous drainage blood reinfusion method in primary total knee arthroplasty does not have significant clinical benefit over no-drain method with regards to allogenic blood transfusions, narcotics uses, the incidence of complications and rehabilitation processes.

‘Tribology’ is derived from the Greek word “tribos” and means the “science of rubbing”. Friction, lubrication, and wear mechanism in the common English language means the precise field of interest of tribology. Wear of PE insert has often been reported in TKA to be primary causes of complications and failure.

As a friction, the wear that occurs in TKA is system properties rather than intrinsic material properties and is therefore affected by multiple variables such as design, material properties, duration and alignment. The contact area on each condyles varies from about 150 mm² for moderate to high-conformity knees in flexion, down to 30 mm² for low-conformity. The corresponding maximum compressive pressure in activity is 10 to 50 MPa, which favor fatigue and deformation of UHMWPE (yield stress: 15MPa). In contrast, fully conforming mobile bearing knees have contact area of at least 300 mm² on each condyles, giving maximum pressure of only 5 MPa. There are several mechanisms whereby small PE particles are released in TKA. Some of these mechanisms are fatigue processes requiring numerous cycles of sliding. Multidirectional sliding is more damaging than sliding in same direction. The wear mechanisms in TKA are as follows:

Adhesive wear

There have been a number of published studies on the in vivo wear measured on retrieved total knee bearings. These studies indicated more clinical wear on the medial side. Patterns of wear varied greatly among individual knees; a majority showed very similar extents of wear on the medial and lateral sides, however there were cases with significantly more wear on one condylar articulation than the other. Evidence of edge loading was common and seen most frequently in the central zone of the medial condylar area.

Wound complication including superficial infection is a concern after total knee arthroplasties (TKA) in diabetics. However, influence of glycoregulation before TKA has not been investigated in relationship to wound healing. Our hypothesis was that glycated hemoglobin (HbA1C), since it reflects long-term regulation of blood glucose, might be associated with incidence of wound complications after TKA in diabetic patients.

We retrospectively reviewed 167 TKAs performed in 115 patients with diabetes mellitus between January 2001 and March 2007. All patients were diagnosed as type II DM and osteoarthritis. A wound complication was defined as a hematoma, bulla, drainage or superficial infection. Stepwise multivariate logistic regression was used to identify which variables had a significant effect on the risk of wound complications. Variables considered were age, gender, body mass index, histories of previous knee surgery, comorbidities, duration of diabetes, the methods of diabetes treatment, complications of diabetes, preoperative HbA1c level, operation time, antibiotics-impregnated cement use, the amount of blood transfusion, and postoperative blood glucose level.

The overall incidence of wound complications was 6.6% (n=11) including superficial infection in 1.8% (n=3), hematoma or bullae in 3.6% (n=6), and drainage in 1.8% (n=3). There were seven cases (4.2%) of deep infection. A multivariate logistic regression revealed that independent risk factors for the development of wound complications were preoperative HbA1C ≥ 8% (odds ratio 6.074, 95% confidence interval 1.119–32.971) and operation time (odds ratio 1.013, 95% confidence interval 1.000–1.026).

Poorly controlled hyperglycemia before surgery may increase the incidence of wound complications among diabetic patients receiving total knee arthroplasties. The correlation of glycemic control and wound complications may assist in the preoperative evaluation and selection of time for surgery.

Introduction and Aims: A significant proportion of patients currently undergoing total knee arthroplasty have uni-compartmental disease. Unicondylar knee replacement (UKA) offers the benefits of less bone resection and better soft tissue retention. However, knee kinematic changes after UKA have not been established.

Method: A significant proportion of patients currently undergoing total knee arthroplasty have uni-compartmental disease. Unicondylar knee replacement (UKA) offers the benefits of less bone resection and better soft tissue retention. However, knee kinematic changes after UKA have not been established.

Results: In the normal knee, knee flexion was accompanied by femoral rollback and tibial internal rotation. Similar patterns of rollback and rotation were seen after UKA. Surprisingly, resecting the ACL did not affect rollback or tibial rotation. However, tibial rotation was significantly different and was more variable after TKA. This suggests that loss of the ACL may not be the major cause of abnormal kinematics after TKA.

Conclusion: Abnormal kinematics have been previously reported after TKA. However, UKA appeared to maintain normal kinematics. This study reported kinematic advantages to UKA, in addition to less bone resection and better recovery.