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.