INTRODUCTION

The majority of papers covering MIS total knee describe a surgical approach where the quads tendon is violated. This presentation describes a modified subvastus approach using MIS technique. The results are compared to the regular subvastus approach.

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.

Background. Achieving full flexion is critical for total knee arthroplasty patients in the Middle East and Asia, where activities of daily living require a full range of motion. Published kinematic data for these populations is limited. The objective of this study was to compare the normal knee kinematics of Muslim subjects with those of Muslim total knee arthroplasty (TKA) patients with high flexion arthroplasties.

Methods: An electromagnetic tracking system was used to record the motion of the lower limb segments of 14 normal Muslim subjects and 10 Muslim TKA patients. Subjects performed high flexion activities of daily living such as kneeling, Muslim prayer, sitting cross-legged and squatting.

Results. For most activities, the range of motion and maximum angles in three dimensions did not significantly differ between the normal and TKA groups. A statistically significant difference in the mean range of flexion/ extension (but not the mean maximum flexion or mean maximum extension values) was found for the prayer activity only. The majority of normal subjects exhibited an internal rotation pattern with two distinct inflection points and a parabolic abduction pattern over the range of flexion. Fewer TKA patients exhibited these patterns.

Conclusions: Overall, the range of motion and ability to perform activities of daily living did not differ between normal Muslim subjects and Muslim TKA patients with a high flexion mobile bearing total knee arthroplasty. However, patterns of internal rotation and abduction that were exhibited by the majority of normal subjects were evident in fewer TKA patients. Therefore, although the range of motion was not significantly affected by the prosthesis, the patterns of motion for some subjects may have changed.

Introduction: The majority of implants available in the market today were designed to allow for a flexion up to 130 degree angle. The LPS 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 Flex knee.

Materials and Methods: From January 1999 to Dec 2006, 1773(Over seventeen hundred) surgeries were performed on patients treated for advanced osteoarthritis. 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 130 degree angle sit on the ground with calf touching thigh for at least one minute.

Results: 61% obtained full flexion as defined above. The majority of the cases with full flexion had full movement pre-operatively, except for 116 cases. Some complications were reported. There were 6 cases of peroneal nerve palsy, five of dislocation, and three of infection. There was also two case of rupture of MCL ligament, a case of intraoperative tibial plateau fracture and six of supracondylar femur fracture. Five revisions were performed.

Conclusion: 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, in general, it should be stressed that this exceptional result has to do mainly with careful patient selection.

Introduction: Literature fails clearly to indicate an advantage of a mobile bearing over the fixed bearing implant. The purpose of this study is to compare result of mobile bearing verses fixed bearing Total Knee replacement done by single surgeon and to see if there is any advantage for the mobile bearing.

Material and Methods: Eight hundred sixty two cases of a mobile bearing LPS Flex implant was compared to four hundred twenty six cases of fix bearing LPS implant done from January of 2001 to January 2006, both group was performed by the same surgeon and the same postoperative cause was done in both group. Documentation for complication and knee score were done in both groups and statistics and analyses were curried out for this result. Also three kinematics evaluation was curried on for ten patients of each group to asset the tibia femoral movement in both groups in deep flexions.

Result: We had three Knee dislocations in the mobile bearing group none in the fixed bearing group the rest of the complication were similar in both group.

Average range of motion was the same in both groups.

Knee score was similar in both groups.

Canamathic assessment confirmed in both group excessive exteneraltation of the femur over the tibia and in fixed bearing group it confirms the spelling of the lateral femoral condoral from the tibial Plato which wrist concern about the safety Fix bearing in deep flexion.

Discussion and Conclusion: There was no clear advantage of Mobil bearing over fixed bearing implant, mobile bearing requires a better sophistical balance to reduce rate of Knee dislocation postoperatively. The mobile bearing knee seems to be more accommodating to deep flexion over Hundred & Fifty degrees and concern should be raised about the fixed bearing in deep flexion activity.

Introduction: Morbidity and mortality are major concerns after simultaneous bilateral TKA. This paper reviews the results of patients who had simultaneous bilateral TKA (558 patients) and compares it to the results of single TKA (485 patients) carried out by the same surgeon in the same institution using same intra operative and post operative protocols.

Material and methods: 558 patients underwent simultaneous bilateral TKA while 485 underwent single TKA carried out by the same surgeon. The pre-op medical evaluation was carried out by a special multidisciplinary medical team. The decision to proceed with simultaneous TKA was made based on the clinical findings pre operatively. There were no additional special cares for the simultaneous group (central or arterial line) during surgery. Post op protocols were the same for both groups

Results: Blood transfusion was higher in the simultaneous knee surgeries (71%) as compared to (34 %) in a single knee group. We had 8 unscheduled ICU admission in the simultaneous group compared to 2 in the individual. Surprisingly DVT was less common in the simultaneous group. We had one death in the simultaneous group. The average knee score and average range of motion were the same in both groups.

Discussion and conclusion: Simultaneous bilateral TKA is safe. It is more economical and convenient, especially for patients who travel for the surgery. A special multidisciplinary task force is recommended to make the simultaneous knee surgery safe.

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 papers covering MIS total knee describe a surgical approach where the quads tendon is violated. This presentation describes a modified subvastus approach using MIS technique. The results are compared to the regular subvastus approach.

Material and methods: 423 total knee replacements were performed through MIS subvastus approach from November 2002 to February 2004. All cases were performed by the same surgeon. The subvastus approach was modified to allow more quads excursion so the surgery can be performed without dislocating the patella. The data was processed at University of Dundee. The results were compared to the results of 361 cases of standard subvastus approach performed by the same surgeon.

Kanasaki et al. (ISTA 2002) has shown that patients who had subvastus approach were able to regain the ability to do a straight leg raising faster than the standard parapateller incision. The results in this paper confirm the same showing that the ability of patients to rehabilitate is not related only to the size of the incision. Having relatively small incisions help in shorten hospital stay but did not make any difference in blood loss. The subvastus approach the only true quad sparing approach and it can be performed through 10 cm incision safely even in heavy patients with severe knee deformity.

In living normal knee the lateral femoral condyle rolls posteriorly more than the medial side to the extent that in deep flexion the lateral femoral condyle sublux from the tibial surface (Nakagawa et al). The purpose of this presentation is to study the tibiofemoral movement in patients who had full flexion after total knee replacements and to compare it with that of normal knee.

23 knees were scanned using SIEMENS SIREMOBILE Iso-C with 3D Extension C-arm. The system is able reconstruct 3D images that can be viewed from deferent angle and precise measurements of distances between the deferent components of the implant can be made. The knee was scanned while the patient is sitting in kneeling position with the calf touching the thigh (flexion of over 150degree

All the cases studied showed a variable roll back between the medial and lateral femoral condyle. In all cases the lateral roll back was much more than the medial. In 14 cases we confirmed lateral condyle subluxation similar to what is seen in normal knee. The position of the foot (internal or external rotation) during scanning did not affect the lateral femoral condyle role back.

Although previous studies have shown paradoxical types of tibiofemoral movement in patients who have total knee replacements throughout the range of movement, the knees in patients who had full flexion after TKA tend to have the same tibiofemoral movement as the normal knee in deep flexion. The lateral femoral condyles spin off or subluxation could adversely affect the implant components especially if the design does not accommodate this movement. The lateral femoral condyle may sublux from the tibia during kneeling inpatients who had full flexion after TKA. These findings should call for changes in the implant design to accommodate the lateral condyle roll back.

Introduction: In living normal knee the lateral femoral condyle rolls posteriorly more than the medial side to the extent that in deep flexion the lateral femoral condyle sublux from the tibial surface(Nakagawa et al). The purpose of this presentation is to study the tibiofemoral movement in patients who had full flexion after total knee replacements and to compare it with that of normal knee.

Materials and Methods: 23 knees were scanned using SIEMENS SIREMOBILE Iso-C with 3D Extension C-arm. The system is able reconstruct 3D images that can be viewed from deferent angle and precise measurements of distances between the deferent components of the implant can be made. The knee was scanned while the patient is sitting in kneeling position with the calf touching the thigh (flexion of over 150degree).

Results: All the cases studied showed a variable roll back between the medial and lateral femoral condyle. In all cases the lateral roll back was much more than the medial. In 14 cases we confirmed lateral condyle subluxation similar to what is seen in normal knee. The position of the foot (internal or external rotation) during scanning did not affect the lateral femoral condyle role back.

Discussion: Although previous studies have shown paradoxical types of tibiofemoral movement in patients who have total knee replacements throughout the range of movement, the knees in patients who had full flexion after TKA tend to have the same tibiofemoral movement as the normal knee in deep flexion. The lateral femoral condyles spin off or subluxation could adversely affect the implant components especially if the design does not accommodate this movement.

Conclusion: The lateral femoral condyle may sublux from the tibia during kneeling in patients who have full flexion after TKA. These findings should call for changes in the implant design to accommodate the lateral condyle roll back.

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.

Introduction: The majority of total knee systems available on the market were designed to accommodate limited flexion up to 130 degrees only, which does not satisfy many patients. The LPS Flex was designed to accommodate deep flexion safely (up to 160 degree of flexion). This is the first paper to report the clinical results of 108 TKA using the LPS flex system.

Material and methods: 108 surgeries were preformed on 86 patients from September 1999 to March 2001. All patients were treated for advanced degenerative arthritis. All surgeries were done by one surgeon. The Subvastus approach was used in all cases. Pre-op and post-op ranges of motion were documented. Patients who had over 145 degree of flexion and were able to sit on the ground (calf touching thigh) for at least one minute were considered to have full flexion. Statistical analyses were carried out on the data at University of Dundee.

Results: Full range of motion was obtained in 76 TKA. All these cases had a full movement preoperatively range of motion except for 5 cases. Complication rate were similar to those reported in other series. There were no complications that could be attributed to the ability to fully flex the knee. Full flexion was found to be the same in patients who had simultaneous bilateral total knee and those who had it on only one side.

Conclusion: LPS flex knee design offers a good option for patients who have good preoperative range of motion. The ability to fully flex the knee is important in certain cultures and in active patients of the western society. Our preliminary results show that there was no risk associated with deep flexion.

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 patients with osteoarthritis.

Forty-two quadriceps releases were performed in patients who had TKA. The releases were carried out utilising 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.

The quadriceps release improved the range of motion in all patients; at least 135 degrees of flexion were obtained. The improvements were more dramatic in patients who had previous surgeries. 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 degrees of flexion.

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