Objective To measure the position of patellar high point and the shape of the osteotomy surface, and to analyze their relationship, distribution, and gender differences. Methods A total of 127 patients who needed anterior cruciate ligament reconstruction or meniscus repair due to trauma between September 2020 and September 2021 were selected as the research subjects. There were 71 males and 56 females, with an average age of 30.5 years (range, 19-43 years). There were significant differences in height and body weight between male and female patients (P<0.05), but no significant difference in age and body mass index (P>0.05). The three-dimensional model of the patella was reconstructed in Mimics software based on the CT images of the knee joint, and then imported into Geomagic Studio software for virtual osteotomy of the patella. The horizontal axis and vertical axis of the osteotomy surface represented the total width (W) and total height (H) of the osteotomy surface, respectively. Then the osteotomy surface was divided into four quadrants with the two axes: inner proximal, inner distal, outer proximal, and outer distal, and the inner width (W1), proximal height (H1), outer width (W2), and distal height (H2) were measured. The midpoint of the patellar ridge was selected as the patellar high point, and the point projected onto the osteotomy surface was defined as the optimal point for patellar prosthesis positioning (OPPP). The distances of OPPP on the horizontal axis (L1) and vertical axis (L2) relative to the center of the osteotomy surface were measured and L1/W1 and L2/H1 were also calculated; the quadrant distribution of OPPP was recorded. The patients were grouped according to gender, and the morphological parameters of the osteotomy surface (W, W1, W2, H, H1, H2) and the parameters related to the position of the OPPP (L1, L2, L1/W1, L2/H1) were analyzed between groups. Results The width and height of each osteotomy surface of the patella in males were significantly larger than those in females (P<0.05). As for the relationship between OPPP and osteotomy surface, the L1 of both male and female patients was 1-7 mm, and there was no significant difference in the distribution between the two groups (χ2=8.068, P=0.149); L1/W1 in both male and female patients was mainly 1/10-3/10. The L2 of male patients was 0-5 mm, and that of female patients was –1-4 mm; the difference in distribution between the two groups was significant (χ2=15.500, P=0.006); L2/H1 in both male and female patients was mainly 0-1/5. The OPPP of male patients was mainly distributed in the inner proximal (98.59%) and outer proximal (1.41%) quadrants, while the female patients were distributed in the inner proximal (91.07%), inner distal (7.14%), and outer proximal (1.79%) quadrants. There was significant difference in the OPPP quadrant distribution between the two groups (χ2=5.186, P=0.036). Conclusion The OPPP points are widely distributed but mainly concentrated on around 1/5 of the medial patella surface and around 1/10 of the superior patella surface. A small portion of females’ OPPP were inferior while all males’ OPPP were superior to the center of the patella.
Objective To investigate the method and effectiveness of vacuum seal ing drainage (VSD) combined with debridement for treatment of deep infection after hip or knee replacement. Methods Between September 2006 and May 2010, 13 cases of deep infection after joint replacement surgery were treated, including 5 males and 8 females with an average ageof 62.5 years (range, 56-78 years). Infection occurred at 7 days to 1 year and 2 months (median, 14 days) after joint replacement surgery. The time from infection to admission was 8 days to 4 years and 6 months (median, 21 days). Purulent secretion with or without blood were observed in all patients; sinus formed in 5 cases; and unhealing of incision or drainage opening disunion were observed in 8 cases. The size of skin defect at secretion drainage or sinus opening site was 5 mm × 3 mm to 36 mm × 6 mm; the depth of drainage tunnel or sinus was 21-60 mm. The histopathological examination in 11 patients showed acute infection or chronic infection with acute onset in 10 cases, and tuberculosis in 1 case. In 6 cases of secretion culture, Staphylococcus aureus was isolated from 5 cases. After thorough debridement, wound irrigation was performed during the day and VSD during the night in 10 cases. VSD was merely performed in 3 cases. Results In 1 case after revision total hip arthroplasty, the wound bled profusely with VSD, then VSD stopped and associated with compression bandage, VSD proceeded again 3 days later with no heavy bleeding. All the patient were followed up 1 year to 4 years and 5 months (mean, 2 years and 11 months). Infection were controlled 7-75 days (mean, 43 days) after VSD in 10 cases. In these cases, prosthesis were reserved, no recurrent infection was observed, wound were healed, limb function were reserved. VSD was refused in 1 case because of hypersensitive of the pain at the vacuum site, infection control was failed and amputation at the thigh was proceeded. The effect was not evident in 1 case with tuberculosis infection, then the prosthesis was removed and arthrodesis was proceeded followed by complete union. In 1 case, infection was cured with VSD, recurrent infection happened after 9 months, antibiotic-impregnated cement spacer was used at end, and no recurrence was observed 1 year and 4 months later. Conclusion VSD combined with debridement can drainage deep infection sufficiently, promote wound healing, reduce recurrent infection rate, maximize the possibil ity of prosthesis preservation.