Introduction: Patients with advanced osteoarthritis tend to have limited range of motion; the purpose of this in vivo anatomical study is to identify the anatomical structures responsible for limited knee movement in patient with osteoarthritis.

Materials and Methods: 42 quadriceps releases were performed in patients who had TKA. The releases were carried out utilizing subvastus approach and just before proceeding with the knee replacement surgery. The ranges of motion were documented before and after the release using digital photography and lateral portable x-ray. No bony resection was done, and no ligament release was performed. Quadriceps excursion was also studied under fluoroscopy in six volunteers throughout the range of movement

Results: The quadriceps release improved the range of motion in all patients; at least 135 degrees of flexion were obtained. The average of improvement in knee flexion after the release was 36 degrees. The presence of osteophytes or gross deformity did not influence the degree of improvement. The fluoroscopy study has shown that the average excursion of quadriceps muscle from 0 to 145 degrees is 7 cm. The excursion per degree varies throughout the range of motion; it is more per degree near full flexion and extension than around 90 degree of flexion

Conclusion: The limited excursion of the quadriceps muscle is the main limiting factor to knee flexion. Other pathological changes such as osteophytes, surface pathology, posterior capsule and the cruciate ligaments play very limited roles.

At our institution significant number of patients were able to have full movement after TKA; however the concern is whether deep flexion after TKA will increase certain complications or whether it will cause early damage to the knee components.

384 Total knee replacements were performed from January 97 to January2002. Three deferent knee systems were used (IB2, NEXGEN and LPS Flex). Preoperative and post operative range of motion was document on lateral x-ray. Knee score was documented and data was processed at major university in Scotland. All surgeries were performed by a single surgeon. Patient was considered to have full flexion if he is able to flex the knee over 140 and able to kneel with the calf touching the thigh for at least one minute. Post operative x-ray was reviewed at 1 and 2 years.3D images were obtained on selected cases.

216 Cases had full flexion as per above definition and 168 cases failed to achieve full flexion. There was no significant deference in complication rate between patients who had full flexion and those who did not. The complication rates were similar to that reported in other series. X ray review did not show any component damage in the full the flexion group; however two phenomenons were documented in some patient who had full movement: dig in phenomenon and lateral femoral condyle spin off (confirmed on 3D images).

Full flexion after TKA did not increase complication rates. The significance of dig in and spin off phenomenon needs further investigation

The majority of implants available in the market today were designed to allow for a flexion up to 130 degree angle. The LPS Mobile Flex was designed to accommodate deep flexion, up to 160 degree angle. The purpose of this study is to evaluate the clinical result of the LPS Mobile Flex knee.

From January 1999 to February 2004, 635 surgeries were performed on patients treated for advance osteoporosis. All the surgeries were carried out by the same surgeon. The majority of the patients had bilateral total knee replacements simultaneously. Pre-operative ranges of motion were documented on lateral x-ray. Patients were considered to have full flexion if they were able to fix the knee to at least 140 degree angle sit on the ground with calf touching thigh for at least one minute.

68% obtained full flexion as defined above. The majority of the cases with full flexion had full movement pre-operatively, except for 26 cases. Some omplications were reported. There were 2 cases of personal nerve palsy, three of dislocation, and one of infection. There was also a case of rupture of MCL ligament, a case of intra-operative tibial plateau fracture and one of upra-condyler femur fracture. No revision was performed. There were no patella complications

The LPS Flex Implant had a similar complication rate to those reported by other series. There was no complication that could be specifically attributed to deep flexion. Surprisingly, there were no patella complications and the implant, in general, had an excellent clinical outcome as far as mobility. However, it should be stressed that this exceptional result has to do mainly with careful patient selection.

Introduction Full flexion is important for daily living activities in Asian societies. The purpose of this presentation is to discuss our experience with full flexion after knee replacement in over 900 cases and to address some areas of concern.

Materials and Methods 911 cases were performed on 492 patients. LPS flex implants were used; all surgeries were performed by a single surgeon between December 1999 and august year 2004. Data was processed at University of Dundee in Scotland. MIS subvastus approach was used. Full flexion was defined as a flexion of over 135 degree with the ability to kneel on the ground, calf touching thigh for at least one minute. X-ray review was carried on cases with more than 2 years of follow up.

Results 67% of patients were able to get full flexion after surgery. The majority of those cases had full flexion pre-operatively. The results were compared with the data base at University of Dundee: our patients has significantly better flexion than the data base yet the knee score was almost the same .Complication rates were the same and there was no complication that can be attributed to deep flexion.

Discussion The result clearly shows that in spite of the fact that patient has a better range of motion the knee score failed to capture the improvement of patient function. It is unfortunate that we still do not have a universal way to describe the activities of deep flexion and no objective methods to assess the importance of deep flexion on daily activities. There is still great need to improve our understanding of the biomechanics of deep flexion so we can choose proper implants for our patients. Our x-ray review shows that mobile bearing is better choice in accommodating the lateral femoral condyle subluxation that happens with deep flexion and we were able to document that on 3D images.

Conclusion Full flexion is achievable and safe after TKA. Further work will be needed to develop new ways to asses function after TKA and to further modify the implant to accommodate deep flexion.