Restoration of the distal femur impacts patellar height in revision TKA.

BACKGROUND: Restoring patellar height is important in revision TKA for normal knee function and kinematics. Alteration in patellar height after revision TKA is associated with inferior extensor mechanism function. QUESTIONS/PURPOSES: We determined whether gap balancing with bone preservation and distal femoral augmentation would restore patellar height and patellar height changed in patients undergoing septic and aseptic revision TKA. PATIENTS AND METHODS: We retrospectively reviewed 76 patients who had revision TKA between 2006 and 2009; 12 had two-stage revisions for infected TKA, and 64 had revision for aseptic failure. We compared preoperative and postoperative radiographs and measured the patellar height using the Insall-Salvati ratio in both groups. We reviewed operative records to determine type of exposure and amount of distal femoral augmentation used to restore the joint line. RESULTS: Overall mean preoperative and postoperative Insall-Salvati ratios were 1.02 and 1.04, respectively. In the septic group, mean preoperative and postoperative Insall-Salvati ratios were 1.07 and 0.99, respectively. In the aseptic group, mean preoperative and postoperative Insall-Salvati ratios were 1.01 and 1.05, respectively. Overall, nine patients had preoperative patella baja; seven of these had an improvement to normal height. There was little difference in preoperative and postoperative Insall-Salvati ratios in patients with patella alta. Distal augmentation was used in 10 of 12 patients in the septic group and 48 of 64 patients in the aseptic group. CONCLUSIONS: Surgeons can maintain normal patellar height and improve patella baja by preserving bone stock and using distal femoral augments to restore the distal joint line during revision TKA.

The Ratio of the Distal Femur Width to the Tibial Plateau Width with Advancing Age.

Historically, intraoperative analysis of knee fracture procedures relied upon a fluoroscopic reduction assessment by the surgeon. This is a subjective assessment due to the lack of linear measurement reference data. Compared with the knee, the ankle and wrist have well-established bony anatomical relationships to guide reduction assessment during fracture treatment. The purpose of this study was to (1) determine the width ratios in the knee (plateau to femur) with aging, and (2) determine knee width changes with aging. One-hundred and fifty consecutive uninjured knee radiographs were reviewed. In all age groups, the width ratio of the articular distal femoral (ADF) to the articular tibial plateau (ATP) is greater than 1.0 and between 1.03 and 1.05. The tibia plateau width is on average 9.34 mm wider and the femoral width is 8.0 mm wider in the 61 to 80 age group than the ATP and the ADF in the younger age groups. In conclusion, the articular tibial plateau width and the articular distal femoral width are nearly equal across ages 20 to 80 years. An absolute articular width value by age cannot be assigned because articular widths change with aging.

Comparison of PACS and hard-copy 51-inch radiographs for measuring leg length and deformity.

BACKGROUND: The picture archiving and communication system (PACS) eventually will replace the use of standard hard-copy radiographs. It is unknown whether measurements of limb length discrepancy (LLD) and deformity on PACS compare in accuracy and reproducibility with those from hard-copy radiographs. QUESTIONS/PURPOSES: We compared the reproducibility and reliability of LLD and deformity measurements for each of these two media. METHODS: We retrospectively reviewed 51-inch standing lower extremity images obtained for LLD or deformity analysis from 40 patients to compare the measurements and their reliability on hard-copy film with those performed on soft-copy PACS. Two observers independently performed measurements twice using each system at 1-week intervals to minimize interobserver or intraobserver bias. Intraclass correlation coefficients (ICCs) were determined to test intraobserver and interrater reliability of Rater 1 and Rater 2. RESULTS: Interrater reliability of measurements made on hard copy ranged from 0.69 to 0.99 and PACS-derived measurements ranged from 0.66 to 0.98. Intraobserver reliability for Rater 1 for measurements made on hard copy ranged from 0.853 to 0.999 and PACS-derived measurements ranged from 0.80 to 0.996. Intraobserver reliability for Rater 2 for measurements made on hard copy ranged from 0.931 to 0.999 and PACS-derived measurements ranged from 0.962 to 0.999. CONCLUSIONS: Each system yielded comparable reliability for measurements, therefore, transition to PACS to perform measurements in patients with LLD or deformity can be made with confidence. LEVEL OF EVIDENCE: Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Limited quadricepsplasty for contracture during femoral lengthening.

UNLABELLED: Extension contracture of the knee is a common complication of femoral lengthening. Knee flexion exercises to stretch the contracture with physical therapy can be effective but take a prolonged amount of time to work and place increased stress across the patellofemoral joint. We developed a minimal-incision limited quadricepsplasty surgical technique to treat knee extension contracture secondary to femoral lengthening and retrospectively reviewed 16 patients treated with this procedure. The mean age of the patients was 23 years. Range of motion of the knee and quadriceps strength were recorded preoperatively, after femur lengthening but before additional surgery, after quadricepsplasty, and at each followup. The mean femoral lengthening performed was 4.4 cm. We compared range of motion and time to regain knee flexion with those of historical controls. The minimum followup after quadricepsplasty was 6 months (mean, 38 months; range, 6-84 months). The mean range of motion was 129 degrees preoperatively, 29 degrees after the distraction phase of femoral lengthening, and 108 degrees after limited quadricepsplasty, and at final followup, the mean knee flexion was 125 degrees . There were no major complications. Limited quadricepsplasty improved knee flexion after a knee extension contracture developed secondary to femoral lengthening. In comparison to historical controls who did not have quadricepsplasty, the patients with limited quadricepsplasty had quicker return of knee flexion, although there was no difference in knee flexion achieved ultimately. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

VKORC1 variant genotypes influence warfarin response in patients undergoing total joint arthroplasty: a pilot study.

UNLABELLED: Warfarin dosing algorithms do not account for genetic mutations that can affect anticoagulation response. We retrospectively assessed to what extent the VKORC1 variant genotype would alter the likelihood of being a hyperresponder or hyporesponder to warfarin in patients undergoing total joint arthroplasty. We used the international normalized ratio (INR) on the third postoperative day of 3.0 or greater to define warfarin hyperresponders and 1.07 or less to define hyporesponders. A control group of normal responders was identified. From a cohort of 1125 patients receiving warfarin thromboprophylaxis, we identified 30 free of predisposing factors that could affect warfarin response: 10 hyperresponders, eight hyporesponders, and 12 normal responders. Homozygous carriers of the VKORC1 mutant AA genotype were more likely (compared with carriers of GA or GG genotypes) to be hyperresponders (odds ratio, 7.5; 95% confidence interval, 1.04-54.1). Homozygous carriers of the GG (normal) genotype were more likely (compared with carriers of AA or GA genotypes) to be hyporesponders (odds ratio, 9; 95% confidence interval, 1.14-71). Preoperative screening for the VKORC-1 genotype could identify patients with a greater potential for being a hyperresponder or hyporesponder to warfarin. This may allow an adjusted pharmacogenetic-based warfarin dose to optimize anticoagulation, reducing postoperative risks of bleeding and thrombosis or embolism. LEVEL OF EVIDENCE: Level III, diagnostic study.

Osgood Schlatter syndrome.

PURPOSE OF REVIEW: Osgood Schlatter syndrome presents in growing children (boys, 12-15 years; girls, 8-12 years) with local pain, swelling and tenderness over the tibial tuberosity. Symptoms are exacerbated with sporting activities that involve jumping (basketball, volleyball, running) and/or on direct contact (e.g. kneeling). With increased participation of adolescent children in sports, we critically looked at the current literature to provide the best diagnostic and treatment guidelines. RECENT FINDINGS: Osgood Schlatter syndrome is a traction apophysitis of the tibial tubercle due to repetitive strain on the secondary ossification center of the tibial tuberosity. Radiographic changes include irregularity of apophysis with separation from the tibial tuberosity in early stages and fragmentation in the later stages. About 90% of patients respond well to nonoperative treatment that includes rest, icing, activity modification and rehabilitation exercises. In rare cases surgical excision of the ossicle and/or free cartilaginous material may give good results in skeletally mature patients, who remain symptomatic despite conservative measures. SUMMARY: Osgood Schlatter syndrome runs a self-limiting course, and usually complete recovery is expected with closure of the tibial growth plate. Overall prognosis for Osgood Schlatter syndrome is good, except for some discomfort in kneeling and activity restriction in a few cases.