Posterior-stabilized Arthroplasty Versus Cruciate-retaining Arthroplasty in Treatment of Osteoarthritis: a 5-year Follow-up Study

Backgroud: A prospective cohort study was performed to compare clinical outcomes between cruciate-retaining (CR) and posterior-stabilized (PS) arthroplasty.Methods: In total, 210 patients (210 knees) underwent CR arthroplasty (n=102) and PS arthroplasty (n=108) from January 2014 to January 2015. The Knee Society Score (KSS), range of motion, patellar stability, and complications were compared between the CR and PS groups 5 years postoperatively. Results: The CR group comprised 99 knees and the PS group comprised 105 knees at the 5-year follow-up. In the CR and PS groups, the mean postoperative KSS improved to 90±5 and 91±4, and the function score improved to 87±4 and 84±6, respectively (p>0.05). The mean postoperative range of motion was −2°±3° extension to 114°±8° flexion in the CR group and −2°±4° extension to 126°±7° flexion in the PS group, with no significant difference (p>0.05). In terms of patellofemoral complications, eight patients had patellar clunk syndrome, one had patellar subluxation, and one had patellar lateral facet fracture in the PS group. Three patients had patellar clunk syndrome, and one had symptomatic subluxation in the CR group. These patellofemoral complications were significantly different between the groups (p<0.05).Conclusions: CR and PS TKA can achieve good clinical outcomes with respect to the KSS. Better knee flexion but more patella complications in the PS arthroplasty than CR group 5 years postoperatively.Trail registration: This study was approved by our hospital institutional ethics committee.

Three-dimensional motion of the patella in French bulldogs with and without medial patellar luxation

Background French bulldogs exhibit significantly larger femoral external rotation and abduction than other breeds. We were curious as to whether this peculiar leg kinematic affects patellar motion and/or might induce medial patellar subluxation (MPSL) or medial patellar permanent luxation (MPPL). We hypothesized that the more abducted leg posture during stance causes an unusual medial pull direction of the rectus femoris muscle during stance, and that this may facilitate the occurrence of MPSL or even MPPL during locomotion. To test our hypothesis, we analyzed existing stifle-joint X-ray-sequences collected during the treadmill walk and trot of seven adult female French bulldogs. We estimated 3D-patellar kinematics using Scientific Rotoscoping. Results The three-dimensional motion of the patella comprises rotations and translations. From the seven dogs analyzed, three exhibited MPSL and one MPPL during the gait cycle. Medial patellar luxation (MPL) occurred mostly around toe-off in both gaits studied. Patellar position was generally not gait-related at the analyzed timepoints. In dogs with MPL, the patella was placed significantly more distally (p = 0.037) at touch-down (TD) and at midswing (p = 0.024), and significantly more medial at midswing (p = 0.045) compared to dogs without MPL. Conclusions Medial patellar luxation seems to be the consequence of the far from parasagittal position of the stifle joint during stance due to a broad trunk, and a wide pelvis. This peculiar leg orientation leads to a medial sideway pull caused by the rectus femoris muscle and the quadriceps femoris and may initiate plastic deformation of the growing femur and tibia. Thus, a way to avoid MPL could be to control breeding by selecting dogs with lean bodies and narrow pelvis. Actual breeding control programs based on the orthopedic examination are susceptible to errors. Systematic errors arise from the fact that the grading system is highly dependent on the dog’s condition and the veterinarians’ ability to perform the palpation on the stifle. Based on our results, the position of the patella at TD, or even perhaps during stand might offer a possibility of an objective radioscopic diagnostic of the MPL.

Controversy: supporting patellar resurfacing in total knee arthroplasty – do it

Patellar resurfacing during total knee arthroplasty remains a controversial topic. Some surgeons routinely resurface the patella to avoid the increased rates of postoperative anterior knee pain and reoperation for secondary resurfacing, whilst others selectively resurface based on the presence of preoperative anterior knee pain, damaged articular cartilage, inflammatory arthritis, isolated patellofemoral arthritis, and patellar subluxation and/or maltracking. A third group of surgeons never resurface the patella. The anatomy and biomechanics of the patellofemoral joint as well as the advances in surgical techniques and prosthetic design must be taken into account when making a decision about whether to resurface the patella. Accurate component implantation if the patella is resurfaced becomes crucial to avoid complications. In our institution before 2008 we were performing a selective resurfacing of the patella, but in the last decade we have decided to always resurface it, with good outcomes and low complication rate. A reproducible surgical technique may be helpful in reducing the risk of postoperative anterior knee pain and complications related to implants. In this article we analyse the current trend and controversial topics in dealing with the patella in total knee arthroplasty, and discuss the available literature in order to sustain our choice. Cite this article: EFORT Open Rev 2020;5:785-792. DOI: 10.1302/2058-5241.5.190075

Epidemiological Patterns of Patellofemoral Injuries in Collegiate Athletes in the United States From 2009 to 2014

Background: As many as 30% of patients with knee pain seen in sports medicine clinics have complaints related to the patellofemoral joint. There is a paucity of research available regarding patellofemoral injuries, mechanism of injury, and playing time lost in collegiate athletes. Purpose: To describe the rates, mechanisms, severity, and potential sex-based differences of patellofemoral injuries in collegiate athletes across 25 National Collegiate Athletic Association (NCAA) sports. Study Design: Descriptive epidemiology study. Methods: Data from the 2009-2010 through the 2013-2014 academic years were obtained from the NCAA Injury Surveillance Program and were analyzed to calculate patellofemoral injury rates, mechanisms of injury, time lost, and need for surgery. Rate ratios and injury proportion ratios were used to quantify discernible differences between sex-comparable sports and timing of injury (ie, practice vs competition), respectively. Results: The overall patellofemoral injury incidence rate was 16.10 per 100,000 athlete-exposures (AEs). Women’s volleyball had the highest incidence of all sports (39.57 per 100,000 AEs). Injuries were 66% more likely to occur in competition than during practice. Female athletes experienced significantly more patellofemoral injuries than males in similar sports. Patellar tendinitis accounted for 49.2% of all patellofemoral injuries and was the most common injury in 20 of 25 studied sports. Patellar subluxation accounted for the most total days missed, and patellar dislocation had the highest mean days missed per injury (11.42 days). Patella fracture was the most likely injury to require surgery (80%). Conclusion: Patellofemoral injuries were most common in sports that require jumping and quick changes of direction, specifically women’s volleyball, men’s and women’s basketball, and women’s soccer. The majority of patellofemoral injuries in this cohort were classified as patellar tendinitis caused by overuse. Most injuries resulted in no competition or practice time lost. This information may contribute to the development of prevention programs aimed at addressing the most prevalent types and mechanisms of injury in each sport to reduce the incidence of patellofemoral injury in these athletes.

Empty Sunrise Sign: An Arthroscopic Finding in Recurrent Patellar Dislocation

Patellar dislocation is a relatively common knee injury and can be challenging to diagnose. We describe an arthroscopic finding we noted in recurrent patellar dislocation. Arthroscopic photos were evaluated from 50 knees with a history patellar dislocation and 100 control patients. We quantified the amount of patellar subluxation seen on a single arthroscopic view and coined it Empty Sunrise Sign if the patella did not overlap the trochlea. Empty Sunrise Sign was found in 82% of 50 cases with recurrent patellar dislocation and none of the 100 control cases. The finding was 100% specific for identifying a recurrent patellar dislocator. High interobserver agreement was noted. Empty Sunrise Sign suggests significant capsular laxity. This may need to be considered in the surgical treatment of recurrent patellar dislocation.