[Dermal hypoesthesia after total knee arthroplasty].

OBJECTIVE: To observe the incidence of skin sensory loss after total knee arthroplasty (TKA) and its natural history over time, and to identify the relationship between numbness area and incision length, tourniquet time, age and gender. METHODS: In the study, 132 patients (20 males and 112 females, with an average age of 69.75 years old, 135 cases of TKA) who underwent primary TKA with midline incisions were chosen and grouped chronologically (4 years, 3 years, 2 years, 1 year, 6 months, 1 month) to the investigation time point from Peking University First Hospital. All the operations were done by the same surgeon team with Stryker NRG and Depuy RP (without patellar resurfacing). Numbness incidence, numbness area, scar length, tourniquet time were recorded from the questionnaires sent to the patients and their medical records. RESULTS: 84.44% of the patients received a reduced skin sensory after TKA, 91.22% of which had a smaller numbness area gradually over time. The numbness area was decreased from the 1 month postoperation group to the 4 years postoperation group (P <0.001). The numbness area in 2 years postoperation group and more were significantly smaller than 1 month postoperation group (P=0.042, 0.004, 0.022), however, the skin flap numbness area had little change after 2 years (P>0.05). The hypoesthesia flap was completely lateral to the incision in 88.60% of the patients, and the numbness area covered the lateral skin and part of media skin to the incision in 11.40% of the patients. Numbness size had no relationship with the patients' gender, age, length of scar and tourniquet time (P>0.05). CONCLUSION: Most but not all the patients have a dermal hypoesthesia after total knee arthroplasty. The numbness area will gradually reduce over time. Numbness size is obviously smaller 2 years postoperation and then it will be stable. Gender, age, length of incision, and tourniquet time have no significant relationship with the size of numbness.

[Acetabular revision using acetabular reinforcement cages with a hook].

OBJECTIVE: To evaluate the effects of cementless revising cup or acetabular reinforcement cages for reconstructing the massive acetabular deficiency. METHODS: From September 2001 to September 2008, 22 loosening acetabular cases (24 hips) were revised using cementless revising cup or acetabular reinforcement cases for reconstructing massive bone defect after particulate bone grafting. There were 2 cases (2 hips) using Lima cementless revising cup, 2 cases (2 hips) using Kerboull ring, and 18 cases (20 hips) using restoration GAP cages. Six cases (6 hips) were male, and 16 cases (18 hips) were female. The mean age was 62 years old (34 - 79 years old). Septic loosening was in 2 cases (2 hips), and aseptic loosening in 20 cases (22 hips). The mean follow-up was 48 months (18 - 84 months). RESULTS: There was no clinical or radiological evidence of loosening for the revising acetabular components at the last follow-up point. The mean Harris hip score was improved significantly from 56 points (44 - 75) before revision to 89 points (78 - 94) at the last follow-up after revision. Excellent and good rate was 95.5% (21/22 cases). The average abduction angle of the three types of acetabular reconstructive cages were 50.1 degrees (39.0 degrees - 66.0 degrees), and almost all cases of the hip rotation center were restored after revision surgery. At the last follow-up, the reinforcement cages were no immigration and breakup, and there was no radiolucent line around the acetabular components. The bone graft integrated well into surrounding acetabular bone. CONCLUSION: The method of revising the massive acetabular bone defect by cementless revising cup and acetabular reinforcement cages restores the normal hip rotation center, supplies the primary stability of the revising component, and protects the bone graft from mechanical overload during its revascularization phase, which is a reliable method for revising the massive acetabular deficiency after total hip arthroplasty.

[Polyethylene wear and osteolysis in H/G cementless total hip arthroplasty].

OBJECTIVES: To measure the linear polyethylene wear with use of a computer-assisted two-dimensional method, and to evaluate the relationship between wear and long-term clinic-radiological findings. METHODS: Between December 1991 and December 1995, the senior author performed 40 primary total hip arthroplasties with use of H/G porous-coated acetabular component. Radiographs of 40 H/G cementless total hip arthroplasties were examined for osteolysis, radiolucent line, cup migration and so on. To measure the linear polyethylene wear, migration in the femoral head center relative to the cup shell center was calculated on digitized consecutive radiographs with special computer software program. RESULTS: The minimum follow-up was 10 years. Total linear wear was 2-8 mm, the mean rate of linear polyethylene wear was (0.32+/-0.31) mm/year. Twelve acetabular components (30%) were revised at an average follow-up point of 12 years. Three types of polyethylene liner failure were identified: wear-through of the polyethylene liner with resultant metallosis (5 hips), excessive wear necessitating revision (5 hips), and polyethylene liner dissociation without gross evidence of wear (2 hips). CONCLUSIONS: High wear rates and femoral and acetabular osteolysis have been and still are the main problems in uncemented total hip replacement. There is clear relationship between wear and acetabular osteolysis or loosening of the prostheses. The poor long-term results with these uncemented total hip arthroplasties illustrate the necessity of regular radiographic evaluation in order to detect osteolysis and liner failure, which are both generally asymptomatic until catastrophic failure appears.

Intraarticular Injection of Allogenic Mesenchymal Stem Cells has a Protective Role for the Osteoarthritis.

BACKGROUND: Researchers initially proposed the substitution of apoptotic chondrocytes in the superficial cartilage by injecting mesenchymal stem cells (MSCs) intraarticularly. This effect was termed as bio-resurfacing. Little evidence supporting the treatment of osteoarthritis (OA) by the delivery of a MSC suspension exists. The aim of this study was to investigate the effects of injecting allogenic MSCs intraarticularly in a rat OA model and to evaluate the influence of immobility on the effects of this treatment. METHODS: We established a rat knee OA model after 4 and 6 weeks and cultured primary bone marrow MSCs. A MSC suspension was injected into the articular space once per week for 3 weeks. A subgroup of knee joints was immobilized for 3 days after each injection, while the remaining joints were nonimmobilized. We used toluidine blue staining, Mankin scores, and TdT-mediated dUTP-biotin nick end labeling staining to evaluate the therapeutic effect of the injections. Comparisons between the therapy side and the control side of the knee joint were made using paired t-test, and comparisons between the immobilized and nonimmobilized subgroups were made using the unpaired t-test. A P value < 0.05 was considered significant. RESULTS: The three investigative approaches revealed less degeneration on the therapy sides of the knee joints than the control sides in both the 4- and 6-week groups (P < 0.05), regardless of immobilization. No significant differences were observed between the immobilized and nonimmobilized subgroups (P > 0.05). CONCLUSIONS: Therapy involving the intraarticular injection of allogenic MSCs promoted cartilage repair in a rat arthritis model, and 3-day immobility after injection had little effect on this therapy.