Introduction

Achieving high flexion after total knee arthroplasty (TKA) is one of the most important clinical results, especially in eastern countries where the high flexion activities, such as kneeling and squatting, are part of the important lifestyle. Numerous studies have examined the kinematics after TKA. However, there are few numbers of studies which examined the kinematics during deep knee flexion activities. Therefore, in the present study, we report analysis of mobile-bearing TKA kinematics from extension to deep flexion kneeling using 2D-3D image matching technique.

Introduction

Total knee arthroplasty (TKA) with a computer-assisted navigation system has been developed to improve the accuracy of the alignment of osteotomies and implantations. One of the most important goals of TKA is to improve the flexion angle. Although accurate soft tissue balancing has been recognized as an essential surgical intervention influencing flexion angle, the direct relationship between post-operative flexion angle and intra-operative soft tissue balance during TKA, has little been clarified. In the present study, therefore, we focused on the relationship between them in cruciate-retaining (CR) TKA with a navigation system.

Using a tensor for total knee arthroplasty (TKA) that is designed to facilitate soft tissue balance measurements with a reduced patello-femoral (PF) joint, we examined the influence of pre-operative deformity on intra-operative soft tissue balance during posterior-stabilized (PS) TKA. Joint component gap and varus angle were assessed at 0, 10, 45, 90 and 135° of flexion with femoral trial prosthesis placed and PF joint reduced in 60 varus type osteoarthritic patients. Joint gap measurement showed no significant difference regardless the amount of pre-operative varus alignment. With the procedures of soft tissue release avoiding joint line elevation, however, intra-operative varus angle with varus alignment of more than 20 degrees exhibited significant larger values compared to those with varus alignment of less than 20 degrees throughout the range of motion. Accordingly, we conclude that pre-operative severe varus deformity may have the risk for leaving post-operative varus soft tissue balance during PS TKA.

Recently, many researches of minimal incision surgery (MIS) total knee arthroplasty (TKA) have been reported, however very few of these contain clinical results. Regardless of this, MIS TKA is widely promoted as an improvement over traditional TKA. Although traditional TKA allows for excellent visualization, component orientation, fixation, and has been associated with remarkable long-term implant survival, many patients expect an extremely small incision, minimal or no pain and discomfort associated with their surgery, and certainly no increase in the complication rate. While there is some evidence that short term benefits may occur, there is concern that there may be an increase in complications with the use of MIS technique. We report here cases that malalignments in early phase were occurred after MIS TKAs. A consecutive series of MIS TKA for varus osteoarthritis undertaken by 2 surgeons at 2 centers during 2-year priod (2006–2007) was reviewed. During this interval, 50 MIS TKAs were performed. The mean age was 75.6 years (range 54 to 88 years). Cases for post-operatively infection were excluded. There were 2 cases that early failures due to varus sinking of tibial component were confirmed in early phase (7 and 3 months after primary surgery). We analyzed data between early failed cases and non-failed cases. Patients with early failure were younger, which showed a trend toward significance (p=0.11; failed; 66.5, non-failed; 75.9 years). There was no difference in amount of both medial and lateral side of distal femoral cut between early failed cases and non-failed cases. Proximal tibial cut was significantly larger in early failed cases compared with non-failed cases (p=0.01; failed; 16.5±4.5, nonfailed; 11.4±6.6). There was no difference in Femorotibial angle (FTA) after surgery between them. Substantial backgrounds of occurring early failure after MIS TKA are not still clarified, however, very early failure were occurred in patients, who had significant large cut of proximal tibia, in our experienced cases. MIS TKA may lead to varus imbalance due to increased amount of bony cut and decreased medial soft tissue release. Henceforth, the high prevalence of MIS failures occurring in early phase is disturbing, because of limited working space and warrants further investigation.

Purpose: A common difficulty with manually-performed total knee arthroplasties (TKAs) is obtaining accurate intra-operative soft tissue balancing, an aspect of this procedure that surgeons traditionally address through their “subjective feel” and experience with an unphysiological joint condition. We have therefore developed a new tensor for TKAs that enables us to assess for soft tissue balancing throughout the range of motion about the knee with a reduced patello-femoral (PF) joint and femoral component in place. This tensor permits us to intra-operatively reproduce the post-operative alignment of the PF and tibio-femoral joints. The main purpose of this study is to compare ligament balance in cruciate-retaining (CR) and posterior-stabilized (PS) TKAs.

Methods: Using the tensor, we intra-operatively compared the ligament balance measurements of CR and PS TKAs performed at 0, 10, 45, 90 and 135° of flexion, with the patella both everted and reduced. From a group of 40 consecutive females (40 varus osteoarthritic knees) blinded to the type of implant received, we prospectively randomized 20 patients to receive a CR TKA (NexGen CR Flex) and the other 20 patients a PS TKA (NexGen LPS Flex). The CR TKA group had a mean age of 73.7 ± 1.3 years while the PS TKA group had a mean age of 73.8 ± 1.7 years.

Results: The mean values of varus angle in CR TKA with the knee at 0, 10, 45, 90 and 135 degrees of flexion were 3.0, 3.2, 2.7, 4.2 and 5.1 ° with the patella everted, and 3.9, 4.2, 2.5, 2.0 and 2.0 ° with the patella reduced. The mean values of varus angle in PS TKA at these same degrees of flexion, respectively, were 3.0, 4.1, 6.0, 6.2 and 6.1 ° with the patella everted, and 3.8, 4.1, 6.3, 6.3 and 4.9 ° with the patella reduced. While the ligament balance measurements with a reduced patella of PS TKAs slightly increased in varus from extension to mid-range of flexion (p< 0.05), these values slightly decreased for CR TKA (p< 0.05). Additionally, the ligament balance at deep knee flexion was significantly smaller in varus for both types of prosthetic knees when the PF joint was reduced (p< 0.05).

Conclusion: Accordingly, we conclude that the ligament balance kinematic patterns differ between everted and reduced patellae, as well as between PS and CR TKA.

Background: The use of computer-assisted navigation system had proved to result in consistently accurate alignment of prosthesis in total knee arthroplasty (TKA), however, the clinical midterm to long-term results remains unclear. The objective of this study is to investigate whether clinical results after computer-assisted TKA is superior to the conventional surgical method at midterm, minimum for 5 years follow-up.

Materials: From October 2002 to May 2003, we implanted 30 posterior stabilized total knee prostheses (PFC Sigma; DePuy Inc) using a computed tomography-free navigation system (Vector Vision) for patients diagnosed as osteoarthritis. A control group of 30 matched total knee prostheses of the same type were implanted via a classical, surgeon-controlled technique. Midterm 5 year clinical results including range of motion and Knee Society Clinical Rating Score were compared with these groups. The navigation group was comprised of 23 women and 4 men with a mean age of 81.0 years (range: 56–89 years) at final follow-up and the manual group was comprised of 23 women and 4 men with a mean age of 78.2 years (range: 51–87 years).The results were analyzed statistically and differences of p < 0.05 were considered statistically significant.

Results: Mean follow-up duration was 68.9 months (range: 60–78 months) in the navigation group and 72.8 months (range: 60–80 months) in the manual group. Total 6 patients (3 patients in each group) were lost to follow-up because of their death or lost contact. The follow-up rate was 90 %. No revision or reoperations were required in this study. The average preoperative knee society knee score (KSS) and knee society functional score (KSFS) in the navigation group were 52.9 points (range: 43–77 points) and 51.4 points (range: 25–80 points), respectively and the average postoperative scores were 89.7 points (range: 64–100 points) and 79.7 points (range: 40–100 points), respectively. The average preoperative KSS and KSFS in the manual group were 50.7 points (range: 43–77 points) and 50.3 points (range: 10–80 points), respectively, and the average postoperative scores were 89.6 points (range: 70–100 points) and 75.2 (range: 5–100 points), respectively. No significant differences were noted between the two groups both pre-and postoperatively. The average preoperative range of motion (ROM) in the navigation group was 105.0° (75°–125°); −8.6° (range: 0° to −25°) for extension and 113.6° (range: 85°–135°) for flexion, respectively. The average postoperative ROM was 113.8° (85°–130°); −1.0° (range: 0° to −10°) for extension and 117.0° (range: 105°–130°) for flexion, respectively. The average preoperative ROM in the manual group was 102.5° (65°–140°); −10.2° (range: 0° to −25°) for extension and 112.7° (range: 75°–140°) for flexion, respectively, the average postoperative ROM was 106.9° (80°–130°); −0.0° (range: 0°) for extension and 106.9° (range: 80°–130°) for flexion, respectively. Although no significant difference was found between preoperative ROM for the two groups, the navigation group showed a significantly better ROM compared to the manual group.

Conclusions: Minimum 5-year follow-up of computer-assisted TKA used in the present study revealed that better ROM was achieved, compared with the conventional surgical method. KSS and KSFS were equally good among these two groups. The results focused on the radiographically malaligned patients and further longer follow-up were needed to reveal whether computer-assisted TKA has true clinical benefits compared with the conventional surgical method.

Purpose: Continuous femoral nerve block (CFNB) has been revealed to be a safe and effective method to decrease postoperative pain after total knee arthroplasty (TKA).

However, optimal duration for CFNB to decrease pain and accelerate rehabilitation program after TKA has not been addressed. We, therefore, compared three groups of patients which had different duration of CFNB (0, 2, and 5days) in this study.

Methods: Sixty patients who received primary TKA for osteoarthritis were divided into three groups based on the duration to receive CFNB for 0day, 2days or 5days (twenty patients for each group). Ropivacaine 2mg/mL was given through the femoral nerve catheter using elastomeric infusers (delivering 2ml/hr for each group).

Outcomes including visual analog scale (VAS) pain scores and range of motion (ROM) were compared at 1st, 3rd, 6th, 14th and 21th days after surgery. In addition, the postoperative date when patients could walk stably with parallel bar, walker, or T-cane were recorded and compared.

Results: At 1st and 3rd day postoperatively, the VAS was significantly better in the CFNB 2 days and CFNB 5 days group than in the CFNB 0 day group (P< 0.05).

ROM did not show significant difference among the three groups over postoperative days 1st to 21st (P> 0.05), although groups with the CFNB showed greater ROM at all time points. The CFNB 5 days group obtained stable walking ability with T-cane earlier than other groups (P< 0.05). No patient had any side effect by having CFNB in this study.

Discussion: Postoperative use of CFNB reduced pain at first 3days, and shorten the time to acquire stable walking ability after TKA. We conclude that CFNB should be kept for 5days after surgery to decrease pain and accelerate rehabilitation program after TKA.

We have developed a new tensor for total knee replacements which is designed to assist with soft-tissue balancing throughout the full range of movement with a reduced patellofemoral joint. Using this tensor in 40 patients with osteoarthritis we compared the intra-operative joint gap in cruciate-retaining and posterior-stabilised total knee replacements at 0°, 10°, 45°, 90° and 135° of flexion, with the patella both everted and reduced.

While the measurement of the joint gap with a reduced patella in posterior-stabilised knees increased from extension to flexion, it remained constant for cruciate-retaining joints throughout a full range of movement. The joint gaps at deep knee flexion were significantly smaller for both types of prosthetic knee when the patellofemoral joint was reduced (p < 0.05).

The haematoma occurring at the site of a fracture is known to play an important role in bone healing. We have recently shown the presence of progenitor cells in human fracture haematoma and demonstrated that they have the capacity for multilineage mesenchymal differentiation. There have been many studies which have shown that low-intensity pulsed ultrasound (LIPUS) stimulates the differentiation of a variety of cells, but none has investigated the effects of LIPUS on cells derived from human fracture tissue including human fracture haematoma-derived progenitor cells (HCs). In this in vitro study, we investigated the effects of LIPUS on the osteogenic activity of HCs. Alkaline phosphatase activity, osteocalcin secretion, the expression of osteoblast-related genes and the mineralisation of HCs were shown to be significantly higher when LIPUS had been applied but without a change in the proliferation of the HCs. These findings provide evidence in favour of the use of LIPUS in the treatment of fractures.

We developed a new porous scaffold made from a synthetic polymer, poly(DL-lactide-co-glycolide) (PLG), and evaluated its use in the repair of cartilage. Osteochondral defects made on the femoral trochlear of rabbits were treated by transplantation of the PLG scaffold, examined histologically and compared with an untreated control group.

Fibrous tissue was initially organised in an arcade array with poor cellularity at the articular surface of the scaffold. The tissue regenerated to cartilage at the articular surface. In the subchondral area, new bone formed and the scaffold was absorbed. The histological scores were significantly higher in the defects treated by the scaffold than in the control group (p < 0.05).

Our findings suggest that in an animal model the new porous PLG scaffold is effective for repairing full-thickness osteochondral defects without cultured cells and growth factors.

We isolated multilineage mesenchymal progenitor cells from haematomas collected from fracture sites. After the haematoma was manually removed from the fracture site it was cut into strips and cultured. Homogenous fibroblastic adherent cells were obtained. Flow cytometry revealed that the adherent cells were consistently positive for mesenchymal stem-cell-related markers CD29, CD44, CD105 and CD166, and were negative for the haemopoietic markers CD14, CD34, CD45 and CD133 similar to bone-marrow-derived mesenchymal stem cells. In the presence of lineage-specific induction factors the adherent cells could differentiate in vitro into osteogenic, chondrogenic and adipogenic cells.

Our results indicate that haematomas found at a fracture site contain multilineage mesenchymal progenitor cells and play an important role in bone healing. Our findings imply that to enhance healing the haematoma should not be removed from the fracture site during osteosynthesis.

We have investigated whether cells derived from haemarthrosis caused by injury to the anterior cruciate ligament could differentiate into the osteoblast lineage in vitro. Haemarthroses associated with anterior cruciate ligament injuries were aspirated and cultured. After treatment with β-glycerophosphate, ascorbic acid and dexamethasone or 1,25 (OH)₂D₃, a significant increase in the activity of alkaline phosphatase was observed. Matrix mineralisation was demonstrated after 28 days and mRNA levels in osteoblast-related genes were enhanced.

Our results suggest that the haemarthrosis induced by injury to the anterior cruciate ligament contains osteoprogenitor cells and is a potential alternative source for cell-based treatment in such injury.

Introduction: Previous in vivo kinematic studies have assessed total knee arthroplasty (TKA) motion under weight-bearing conditions. This in vivo study analyzed and compared posterior cruciate retaining (PCR) and posterior stabilized (PS) kinematics under passive and weight-bearing conditions in subjects implanted with both a PCR and PS TKA.

Methods: Eighteen subjects were implanted with a PCR and a PS TKA, by a single surgeon using a similar surgical technique. Both implant designs had similar condylar geometry. Femorotibial contact positions for all 18 subjects (PCR and PS), implanted by a single surgeon, were analyzed using video fluoroscopy. Each subject,while under fluoroscopic surveillance, performed a weight-bearing deep knee bend and a passive, nonweight-bearing flexion. Video images were downloaded to a workstation computer and analyzed at varying degrees of knee flexion. Femorotibial contact paths for the medial and lateral condyles, axial rotation and femoral condylar lift-off were then determined using a computer automated model-fitting technique. Femorotibial contact anterior to the tibial midline in the sagittal plane was denoted as positive and contact posterior was denoted as negative.

Results: Under passive and weight-bearing conditions, the PCR TKA experienced more paradoxical anterior translation than the PS TKA. Under passive, non weight-bearing conditions, the PS TKA, on average, experienced 3.5 mm of posterior femoral rollback, compared to only 0.6 mm for the PCR TKA. Under weight-bearing conditions, the PS TKA experienced only 0.6 mm of posterior femoral rollback, compared to 0.9 mm for the PCR TKA. The maximum anterior slide was 10.0 mm for the PCR TKA and only 2.7 mm for the PS TKA. There was greater variability in both the PCR and PS anteroposterior data. Subjects having a PCR TKA experienced more normal axial rotation patterns. Sixteen of 18 PCR TKA experienced a normal axial rotation pattern under weight-bearing conditions, while only 9/18 PS TKA experienced a normal pattern. Nonweight-bearing, passive axial rotation patterns were more abnormal for both groups than the weight-bearing patterns. The greatest difference between passive and weight-bearing conditions occurred in the condylar lift-off data. Under passive conditions, both TKA groups experienced significantly greater magnitude and incidence of condylar lift-off. The maximum amount of condylar lift-off under passive conditions was 5.0 mm for the PCR TKA and 6.4 mm for the PS TKA.

Discussion: This is the first in vivo kinematic study to assess a comparison between PCR and PS TKA implanted by the same surgeon in the same patient. Subjects in this study experienced more abnormal kinematic patterns, especially condylar lift-off, when tested under passive, nonweight-bearing conditions. Subjects having a PS TKA experienced less variability in their kinematic data, but PCR TKA, on average, experienced more normal axial rotation and less condylar lift-off.

We describe a patient with a traumatic spondylolisthesis of L5 and multiple, bilateral pedicle fractures from L2 to L5. Conservative treatment was chosen, with eventual neurological recovery and bony union. We are not aware of previous reports of this pattern of injury.

The French word debridement means the removal of the foreign matter or devitalised tissue from a lesion until surrounding healthy tissue is exposed. Arthroscopic techniques facilitated the removal of the intra-articular torn menisci, loose bodies, degenerated articular cartilage, and osteophytes. However, debridement procedure itself cannot induce tissue regeneration thus, the basic goal of the procedure is relief of pain. If pain can be relieved by non-surgical means very few patients can be considered for arthroscopic management. Debridement of early osteoarthritic knees can be carried out with a minimally invasive procedure with extremely low risk of infection and morbidity. However, it should be understood that this procedure is basically indicated for early degenerative knee disease with mechanical problems such as torn menisci or flap lesion of the cartilage.

The general principle is to resect and remove less tissue and preserve the anatomical structure as much as possible. For example in the case of a degenerated horizontal tear of the medial meniscus, the torn fragment can be left alone as long as the remaining segment is not unstable. Arthroscopic removal and shaving of the fibrillated articular cartilage can minimise and reduce crepitation and abnormal sensation of the patello-femoral and tibio-femoral joint but the articular cartilage will not regenerate by this procedure. The longer-term knee function will be better if the anatomical structure is preserved as much as possible.

With increasing awareness of the important functions of the meniscus and the improved understanding of the operative procedure, arthroscopic meniscal repair has become a widely accepted method of treatment for the symptomatic peripheral meniscal tears in the younger athletic population. However, in the patients with degenerative arthritis this procedure is rarely recommended due to the degenerative nature of the repaired meniscus itself.

Recent studies and publications have shown that articular cartilage defects in the younger population can be managed by cartilage cell transplantation, periosteal or perichondral graft, osteochondral autograft, and osteochondral allograft. Good results can be expected by these procedures as long as the cartilage defect is contained and the rest of the cartilage is healthy. Unfortunately, this is not the story for most of the degenerative knee problems thus, excellent results are expected to be limited by arthroscopic treatment.

Relatively large chondral defects with associated degenerative change can be managed by arthroscopic drilling, abrasion arthroplasty, and microfracture. Although cartilage regeneration by these techniques is not predictable and consistent, reasonable results can be obtained in the selective cases with controlled postoperative management. The patients should not be too old and 4 to 8 weeks postoperative non-weight-bearing is needed. Cases treated with this type of approach will be presented and discussed in this presentation.

Currently available knee prostheses can provide 100 to 110° of knee flexion and this is generally good enough to ascend and descend stairs, arise from a chair, and perform most of the daily life activity. However, in certain situations like gardening, sitting on the flat floor and activities that require a squatting position, deep knee bends are required. In some countries, such as Japan, deep knee flexion is very important for the activity of daily life such as leading a life on a Tatami mattress and using a Japanese style toilet. There are several crucial factors, which influence postoperative knee flexion. Those are 1.) preoperative range of motion, 2.) surgical technique, 3.) prosthesis design, and 4.) postoperative rehabilitation.

If a patient has longstanding, poor, preoperative range of motion, then the extensor mechanism itself became stiff in addition to the periarticular fibrotic change of the soft tissue and severe destruction of the bony structure. In this circumstance, it is awfully difficult to obtain deep knee flexion with currently available prostheses and surgical techniques. This indicates that we cannot wait for the last minute to perform TKR if a patient desires to gain deep knee flexion after the surgery.

Surgical technique influences postoperative range of motion significantly. Anatomically the structures that get tight in knee flexion are the extensor mechanism and PCL. Thus, to obtain more flexion you should recess tight PCLs if you choose PCR type prostheses. Since the appropriate amount of PCL recession is not always easy, PCS type prostheses generally yield better flexion. To reduce tension of the extensor mechanism you should resect more patella than usual but this may cause postoperative patellar fracture. Or you can deepen the patellar groove by prosthesis modification but we should remember that both of these techniques will cause loss of the extensor lever arm and power. All posterior overhanging bone should be knocked out after trial reduction of a femoral prosthesis. Slightly flexed positioning of the femoral component and posteriorly tilted positioning of the tibial component can provide better flexion although too much of this positioning causes postoperative extension block.

Regarding the prosthesis design, PCS type prostheses can provide more predictable postoperative knee flexion. Other alternatives are a femoral component with a smaller AP dimension and deep patello-femoral groove. However, both of these will cause weaker extensor power. Posterior lip of the tibial polyethylene decreases the contact pressure in knee flexion but will prevent posterior roll back of the femur and can cause impingement in deep knee flexion. In the normal knee, extreme internal rotation of the tibia occurs in deep knee flexion and this rotation cannot be achieved by a currently available knee design. Mobile bearing prostheses may be needed to achieve better kinematics.

Aggressive postoperative rehabilitation is advised to prevent postoperative contracture of the soft tissue. Finally, although getting deep knee flexion is needed it should be remembered that ensuring postoperative stability and long-term survivorship should always be the most important goal for successful TKR.

We undertook 114 arthroscopic meniscal repairs in 111 patients and subsequently carried out second-look arthroscopy to confirm meniscal healing at a mean of 13 months after repair. Stable healing at the repaired site was seen in 90. Of these, however, 13 had another arthroscopy later for a further tear. The mean period between the repair and the observation of a repeat tear was 48 months. Of the 13 patients, 11 had returned to high activity levels (International Knee Documentation Committee level I or II) after the repair.

An attempt should be made to preserve meniscal function by repairing tears, but even after arthroscopic confirmation of stable healing repaired menisci may tear again. The long-term rate of healing may not be as high as is currently reported. Second-look arthroscopy cannot predict late meniscal failure and may not be justified as a method of assessment for meniscal healing. Young patients engaged in arduous sporting activities should be reviewed regularly even after arthroscopic confirmation of healing.