The Open Orthopaedics

: Introduction: Rupture of a Quadriceps Tendon (QT) following a Total Knee Arthroplasty (TKA) is a rare complication. The purpose of this study was to report outcomes and complications of QT repair following TKA. Methods: From a cohort of 437 QT repairs, 19 individuals were identified who had previously undergone a TKA on the ipsilateral leg. Data was collected on individuals with a minimum follow up of 3 months post QT repair (n=16), including Knee Society Scores, pre and post-operative lag, and pre and post-operative range of motion. Results:


INTRODUCTION
Rupture of the quadriceps tendon following a total knee arthroplasty (TKA) is relatively uncommon.The incidence of this complication is estimated to be between 0.1% and 1.1% [1,2].Attempts to repair the tendon often have poor prognoses leading to lifelong consequences for patients requiring repeat interventions [3,4].Presently, there are three main techniques for treating these tears, including end-to-end primary repair, suture through bone tunnels, and repairs using suture anchors [5,6].Due to the uncommon nature of this event, it is still unclear which of these techniques is superior.The purpose of this study is to compare outcomes of two repair types in the largest cohort in the literature.

MATERIALS AND METHODS
After obtaining approval from our Institutional Review Board, we searched the surgical database at our institution for quadriceps repair surgeries performed between January 1, 2008, and December 31, 2016.Our integrated health care system includes 14 medical centers with over 100 orthopaedic surgeons.Our system does not catalogue surgical cases by CPT codes, rather by interfacility codes.We, therefore, searched for "quadriceps tendon repair" and "open repair of tendon, knee" in our database to identify patients who had undergone a quadriceps tendon repair.A retrospective chart review was then performed to identify those patients who had a prior total knee arthroplasty (TKA) who underwent surgical repair of a quadriceps tear.The operative reports, progress reports, and History and Physical examination, physical therapy notes, and emergency room notes were reviewed and relevant data collected.
Data gathered included age, gender, side of surgery, BMI, use of statins, the length of time between TKA and quadriceps rupture (months), and the length of time from quadriceps rupture to surgical repair.In addition, pre-and post-operative Knee Society Scores (KSS) [7,8], range of motion including extensor lag were recorded.Pre-operative knee society scores were not available in 2 patients and post-operative KSS was only assessed for patients with a minimum of 3 months post QT repair, leaving scores for 16 patients.
Details from the operative report including tourniquet time, repair type, patellar thickness after resection (mm), patellar polyethylene thickness (mm), implant manufacturer, use of auto-or allograft, were recorded.Complications including rerupture, infection, and thromboembolic events were recorded.Patients underwent a 6 week period of immobilization and hinged bracing, as well as non-weight bearing for 6 weeks.Knee flexion was slowly increased each week by a physical therapist.
Chi-square and Fisher's exact tests were used to compare categorical variables.Means and medians of continuous variables were compared using t-tests and Kruskal-Wallis tests as appropriate.Unadjusted odds ratios were calculated using logistic regression.All P values were 2-sided with an alpha = 0.05.Statistical analyses were performed with SAS 9.3 (SAS Institute, Cary, NC).

Patient Demographics
Our database search identified 437 QT repairs.After chart review, we identified 19 patients who sustained a QT disruption following a total knee arthroplasty.The average incidence was 5.5 per 10,000 TKA.There were 10 (52.6%) females.The average age was 67 years (range, 43 to 88 years) at the time of the QT rupture.Fifteen patients were Caucasian, three African-American, and one Asian.Eighteen individuals underwent a TKA for a diagnosis of osteoarthritis and one for rheumatoid arthritis.With respect to predisposing risk factors, there were three active smokers, four patients with diabetes mellitus, eight taking statin medications, and one with stage three chronic kidney disease (Table 1).The average time between TKA to quadriceps tear was 17.2 months (range 1 to 80).
Fifteen disruptions occurred after a primary total knee arthroplasty and four followed a revision total knee arthroplasty.The quadriceps tendon tore as a result of a fall in twelve patients, gradual failure without major event in three patients, and following a peri-prosthetic fracture revision, knee dislocation rising from sitting to standing, and trauma during physical therapy in one patient each (Table 1).The average time from the tear to surgery was 1.86 months (range .13 to 70).

Surgical Findings
Nine patients had complete tears and ten had partial tears.Of those partial tears, 7 were off the superior pole of the patella, 1 from the vastus medialis, 1 from the rectus femoris, and 1 was a midsubstance tear (Table 2).Of the 9 complete tears, 6 were from the superior pole of the patella, 2 from the vastus medialis, and 1 was a midsubstance (Table 2).Three patients underwent a concomitant operation; a lower extremity The QT was repaired in two main methods, suture Anchor or Trans-Osseous repair (ATO) 9 (1 anchor, 5 trans-osseous) and End to End (EE) (13 patients) [5,6].Of the ATO repairs, 4 were complete tears, with only suture anchor repair being done on one of the two partial tears in this group (Table 2).Of the EE repairs, 8 were partial tears and 5 complete tears.

DISCUSSION
The findings of this study show that quadriceps tendon repair following a total knee arthroplasty can improve active knee extension and improve patients' functional outcomes.The EE group had significant improvement in functional outcome and less extension lag compared to the ATO group.
Surgeons often favor EE repairs on patients with partial tears, and perform ATO repairs when the patient has a complex, complete tear.Therefore, the poorer outcomes with regards to post-operative extensor lag would be expected for the ATO group.The idea that the severity of the initial trauma correlates with functional outcomes is supported by the fact that 67% of the ATO group had a lag ≥ 10 degrees compared with just 15% of the EE group.
Additionally, this study showed a low re-rupture rate, even among the more severe complete tears (Table 2).Treatment options should be made on a case by case basis using current guidelines: EE for partial tears and trans-osseous repair for complete tears [3,4,10].The single tear repaired with a Suture Anchor (SA), however, re-ruptured, whereas only one of the four complete tears repaired with trans-osseous repair failed.We believe that the SA technique may be more prone to failure due to the poor bone quality and thinner viable bone available after patellar resurfacing during a TKA.This conclusion supports findings by Bushnell et al. [9] who acknowledged the propensity for suture anchors to undergo stripping during insertion, something that is sure to be magnified in patients with TKAs.This does, however, conflict with the findings in Lighthart et al. [11], but this study did not take into account the thinning of the patella during a TKA.Since there was only one patient in our study that fell into this category and this information conflicts with other studies on the same subject with similarly limited data, more research must be done to confirm this recommendation [6].
The poor outcomes found in this study in regards to rerupture rate and postoperative extensor lag are consistent with those in other papers that document the low success rate of this procedure [2 -4, 12].Although the average KSS increased, there was still a relatively high rate of complications.The rate of infection is consistent with that found in other studies, however, DVTs and re-tears were lower than those seen in previous reports [2,5].
This study is limited due to the small number of patients who qualified for inclusion, especially once individuals were split into ATO and EE cohorts.Furthermore, due to the susceptibility of complications from outside factors, conclusions for long-term outcomes from the procedure may need more exploring.Finally, due to the nature of this surgical procedure, these results are difficult to duplicate since surgeons use different techniques for their repairs and the variable degree in which QT tears can present does not allow for consistency in treatment.Outcomes are slowly continuing to improve, and new techniques are being tested with varying degrees of success, though the overall success of this procedure remains low [12 -15].Nevertheless, it is important to identify these issues quickly and intervene accordingly.

CONCLUSION
Patients who underwent end-to-end repair of quadriceps tendon following total knee arthroplasty had better functional improvements compared to the ATO group and smaller extension lag

ETHICS APPROVAL AND CONSENT TO PARTICIPATE
The study was approved by the ethics committee of Tulane School of Medicine, USA.
hardware removal and placement of antibiotic spacers; a left TKA with revision polyethylene liner; and a right knee irrigation and debridement.