Abstract. Introduction. The Wells score is commonly used to assess the risk of proximal Deep Vein Thrombosis (DVT) following Knee Arthroplasty (KA). The National Institute for Health and Care Excellence (NICE) guidelines recommend an Ultrasound scan in patients with a Wells score of 2 points or more. We wanted to assess how often this protocol resulted in a scan being done and how many were negative. Methodology. Details of all postoperative Ultrasound scans performed up to 90 days were audited in a high-volume unit between 1st January 2016 and 31st December 2020. This included all Lower Limb Arthroplasty patients. Results. Out of a total of 4955 KA (4506 Total Knee Arthroplasty, 449 Unilateral Knee Arthroplasty), 449 (9.1%) had a total of 561 scans, with 17 (3.0%) scans demonstrating a proximal DVT. Thus 97.0% of Ultrasound scans were negative. Conclusion. The present NICE guidelines with the two-Level DVT Wells score are inappropriate for the management of suspected proximal DVT following KA. We propose that swelling that fails to reduce after 4 hours of elevation, or new swelling after a period of recumbent rest, would be more appropriate indications for a scan and negative scans should not be repeated without a change in symptoms. Unless there are pressing clinical indications, therapeutic anticoagulation should not commence in the absence of a diagnosis

Abstract. Aims. The association between body mass index (BMI) and venous thromboembolism (VTE) is well studied, but remains unclear in the literature. We aimed to determine whether morbid obesity (BMI≥40) was associated with increased risk of VTE following total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA), compared to those of BMI<40. Methods. Between January 2016 and December 2020, our institution performed 4506 TKAs and 449 UKAs. 450 (9.1%) patients had a BMI≥40. CT pulmonary angiography (CTPA) for suspected pulmonary embolism (PE) and ultrasound scan for suspected proximal deep vein thrombosis (DVT) were recorded up to 90 days post-operatively. Results. When comparing those of BMI<40 to those with BMI≥40, there was no difference in incidence of PE (1.0% vs 1.1%, p=0.803) or proximal DVT (0.4% vs 0.2%, p=0.645). There was no difference in number of ultrasound scans ordered (p=0.668), or number of CTPAs ordered for those with a BMI≥40 (p=0.176). The percentage of patients with a confirmed PE or proximal DVT were 24.2% and 3.9% respectively in the BMI<40 group, compared to 20.0% (p=0.804) and 2.3% (p=0.598) in the BMI≥40 group. Conclusion. Morbid obesity was not associated with increased risk of PE or proximal DVT within 90 days of TKA or UKA. Overall, 76.3% of CTPAs and 96.2% of ultrasound scans were negative. Increasing the threshold for VTE investigation would reduce the rate of negative investigations. Establishing more effective risk stratification protocols, to guide investigation, would likely reduce unnecessary imaging

Abstract. Introduction. 30-day emergency readmission is an indicator of treatment related complication once discharged, resulting in readmission. A board-approved quality improvement pathway was introduced to reduce elective re-admissions. Method. The pathway involved telephone and email contact details provision to patients for any non-life threatening medical assistance, allowing for initial nurse led management of all issues. A new clinic room available 7 days, and same day ultrasound scanning for DVT studies were introduced. A capability, opportunity and behavior model of change was implemented. Readmission rates before and six months after implementation were collected from Model Hospital. A database used to document patient communications was interrogated for patient outcomes. Results. Prior to implementation, readmission rates following elective primary total knee replacement (TKR) at the 1st business quarter of 2021 (April – June 2021), was 8.7%, (benchmark 3.8%). Following implementation, readmission rates decreased to 4.1% (October – December 2021). 54% of patients making contact were managed with telephone advice. 15% of patients required face-to-face clinic. 32% of those required a same day scan to exclude DVT (1/4). 20 out of 684 TKRs performed following protocol introduction were re-admitted within 30 days. Readmissions were 41% surgical, 29% medical. 52% were unaware of the newly implemented protocol. Further improvements have been made to the protocol based on these findings. Implementation of a suitable pathway can significantly reduce re-admission rates in our center and could be used to reduce readmission rates in other national elective treatment centers

Objectives. The length of the tourniquet time during total knee arthroplasty (TKA) is related to the incidence of post-operative deep vein thrombosis (DVT). Our aim in this study was to investigate the effect of the early release of the tourniquet on the incidence of DVT in patients undergoing TKA. Methods. A total of 200 patients who underwent TKA between November 2015 and November 2016 were prospectively enrolled. The tourniquet was inflated before surgery and released immediately after the introduction of the components (early release group). This group was compared with a retrospective cohort of 200 primary TKAs, in which the tourniquet was released after the dressings had been applied (late release group). The presence of a DVT was detected using bilateral lower limb ultrasonography. Peri-operative clinical and follow-up data were collected for analysis. Results. The incidence of DVT in the early release group (9 of 196, 4.6%) was significantly lower compared with the late release group (24 of 200, 12%; odds ratio (OR) 0.35, 95% confidence interval (CI) 0.16 to 0.78, p = 0.008). The incidence of proximal DVT in the early release group (1 of 196 (0.5%)) was significantly lower than in the late release group (8 of 196, 4%; OR 0.12, 95% CI 0.02 to 0.99, p = 0.020). Although the mean intra-operative blood loss was higher in the early release group, the mean post-operative drainage, total blood loss, transfusion requirements and complications were not significantly different in the two groups. Conclusion. In patients who undergo TKA, releasing the tourniquet early is associated with a decreased incidence of DVT, without increasing the rate of complications. Cite this article: Bone Joint Res 2017;6:535–541

Aims. The optimal management of an infrapopliteal deep venous thrombosis (IDVT) following total knee arthroplasty (TKA) remains unknown. The risk of DVT propagation and symptom progression must be balanced against potential haemorrhagic complications associated with administration of anticoagulation therapy. The current study reports on a cohort of patients diagnosed with IDVT following TKA who were treated with aspirin, followed closely for development of symptoms, and scanned with ultrasound to determine resolution of IDVT. Methods. Among a cohort of 5,078 patients undergoing TKA, 532 patients (695 TKAs, 12.6%) developed an IDVT between 1 January 2014 to 31 December 2019 at a single institution, as diagnosed using Doppler ultrasound at the first postoperative visit. Of the entire cohort of 532 patients with IDVT, 91.4% (486/532) were treated with aspirin (325 mg twice daily) and followed closely. Repeat lower limb ultrasound was performed four weeks later to evaluate the status of IDVT. Results. Follow-up Doppler ultrasound was performed on 459/486 (94.4%) patients and demonstrated resolution of IDVT in 445/459 cases (96.9%). Doppler diagnosed propagation of IDVT to the popliteal vein had occurred in 10/459 (2.2%) cases. One patient with an IDVT developed a pulmonary embolus six weeks postoperatively. Conclusion. The results of this study demonstrate a low rate of IDVT propagation in patients managed with aspirin. Additionally, no significant bleeding episodes, wound-related complications, or other adverse events were noted from aspirin therapy. Cite this article: Bone Joint J 2021;103-B(6 Supple A):18–22

Introduction. There is insufficient data on the trends of anticoagulation after total knee arthroplasty (TKA) in the USA, and the efficacy and safety of rivaroxaban, beyond randomized clinical trials and small cohort studies. Patients and Methods. Using the Truven Health MarketScan database, we retrospectively evaluated new anticoagulation prescriptions after elective TKA from 2010 to 2015. The frequency of deep vein thrombosis (DVT), pulmonary embolism (PE), and adverse events, within 90 days, were then evaluated in 24,856 new users of warfarin and 21,398 new users of rivaroxaban in commercially insured patients (COM), and 15,483 new users of warfarin and 8,997 new users of rivaroxaban in Medicare supplement patients (MED). Data was analyzed by odds ratios using logistic regression models with stabilized inverse probability treatment weighting. Results. Warfarin use decreased from approximately 50% to 17% in COM patients and 60% to 25% in MED patients. Rivaroxaban use increased from 0 to 35% in COM patients and from 0 to 39% in MED patients. Older patients, females, a history of DVT, renal impairment, use of antiplatelet agents or surgery performed as an outpatient had lower odds of getting rivaroxaban. Patients in Western region and having surgery in 2015 had higher odds of getting rivaroxaban. COM patients with capitated insurance plans and a history of PE had lower odds of rivaroxaban initiation. MED patients with atrial fibrillation, cardiovascular disease or hyperlipidemia had lower odds of rivaroxaban initiation. Warfarin users had significantly higher odds ratio of DVT (OR 2.06 in COM patients and OR 2.21 in MED patients) and PE (OR 2.03 in COM patients and OR 2.16 in MED patients) than rivaroxaban users. There were no statistically significant differences in the bleeding risk between the two agents, but warfarin users had a significantly higher odds ratio of periprosthetic infection in both COM (1.57) and MED (1.79) patients. Conclusions. There has been an increase in prophylaxis with rivaroxaban, and a decrease in both warfarin and LMWH use after elective TKA over four years. Rivaroxaban had lower odds ratio of both DVT and PE than warfarin, and bleeding risks were similar. For figures, tables, or references, please contact authors directly

Aims. The aim of this study was to investigate the incidence, risk factors, and outcome of venous thromboembolism (VTE) following anterior cruciate ligament (ACL) reconstruction in a nationwide cohort. Patients and Methods. All ACL reconstructions, primary and revision, that were recorded in the Swedish Knee Ligament Register (SKLR) between 2006 and 2013 were linked with data from the Swedish National Board of Health and Welfare. The incidence of VTE was determined by entries between the day of surgery until 90 days postoperatively based on diagnosis codes and the prescription of anticoagulants. Risk factors, outcome, and the use of thromboprophylaxis were analyzed. Descriptive statistics with multivariate analysis were used to describe the findings. Results. The cohort consisted of 26 014 primary and revision ACL reconstructions. There were 89 deep venous thromboses (DVTs) and 12 pulmonary emboli (PEs) with a total of 95 VTEs (0.4 %). Six patients with a PE had a simultaneous DVT. The only independent risk factor for VTE was age greater than or equal to 40 years (odds ratio 2.31, 95% confidence interval 1.45 to 3.70; p < 0.001). Thromboprophylaxis was prescribed to 9461 patients (36%) and was equally distributed between those with and those without a VTE (37.9% vs 36.4%). All patient-reported outcome measures (PROMs) one and two years postoperatively were significantly lower in those with VTE. Conclusion. The incidence of VTE following ACL reconstruction is 0.4%, and the only significant risk factor is age. Patients with VTE had worse postoperative clinical outcome than patients without VTE. We recommend against the routine use of thromboprophylaxis, but it should be considered in older patients

INTRODUCTION. Tranexamic Acid (TA) has been shown to decrease peri-operative bleeding in primary Total Knee Replacement (TKR) surgery. There are still concerns with regards to the increased risk of thromboembolic events with the use of TA. The aim of this study was to assess whether the use of pre-operative TA increased the incidence of Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE) in TKR. METHODS. Patients who underwent primary TKR between August 2007 and August 2009 were identified from the databases of three surgeons within the lower limb arthroplasty unit. A retrospective case notes analysis was performed. DVT was diagnosed on Duplex Ultrasound Scan and PE on CT Pulmonary Angiogram. A positive result was a diagnosis of DVT or PE within 3 months of surgery. RESULTS. 322 patients underwent primary TKR over the 2 year period. 131 patients received TA pre-operatively. 191 patients did not receive TA prior to surgery. A total of 4 (3.1%) patients who received TA were diagnosed with either a DVT (2) or PE (2) post operatively. In those patients not receiving TA, 6 had a DVT and 2 had a PE, a total of 8 (4.2%). CONCLUSION. Pre-operative use of Tranexamic Acid in primary Total Knee Replacement does not increase the incidence of DVT and PE

Introduction. Expanded indications and patient demand have significantly increased the number of TKA performed in young and active patients under age 55. While improved materials have decreased the likelihood of early catastrophic wear, concerns remain with the performance and survivorship of TKA implants in this patient population. Therefore, the purpose this study is to evaluate the clinical outcomes, complications, and implant survivorship of TKAs performed in patients under age 55. Materials and Methods. We retrospectively reviewed 1194 primary TKA performed for the diagnosis of primary knee osteoarthritis performed at our institution between 2013–2016. There were 291 TKA performed in patients under age 55. Patients were excluded if they had 1) prior history of fracture, 2) renal disease, 3) inflammatory joint disease, and 4) required therapeutic anticoagulation. The primary outcome of interest was rate of revision at 30 days, 1, 2, and 5-year time points. Secondary outcomes included postoperative transfusion rate, calculated blood loss, length of stay(LOS), rate of DVT/PE, readmission and reoperation. Results. Patients under 55 were more likely to be obese and have a lower comorbidity burden. Overall, 31 patients required revision (2.6%; 97.4% survivorship at 5 years). Patients under 55 had significantly higher revision rate at 1(2.4%vs.0.9%; p=0.024), 2(3.8%vs.1.55%; p=0.02) and 5 years (5.5%vs.2.2%; p=0.004). The principal diagnosis for early revision in young patients were 1) instability, 2) infection, and 3) aseptic loosening. There was no difference in rate of transfusion, DVT/PE, LOS and readmissions between the 2 groups. Patients under 55 had a higher rate of all-cause reoperation at all time points. Multivariate regression showed patients under 55 were at significantly higher risk for revision at the latest time point (OR 2.51; p=0.012). Discussion. Despite improvements in the wear characteristics of TKA implants, young and active patients remained at higher risk of early revision compared to older patients even at 1, 2, and 5 years. The data should be used to counsel young prospective TKA patients about the early risk of reoperation and non-wear related complications

We investigated the outcome of deep-vein thrombosis (DVT) in the calf after total knee arthroplasty (TKA) in 48 patients (45 women and three men) by clinical assessment and venographic study between three and four years after surgery. The mean age of the patients was 67.2 ± 7.7 years (52 to 85) and the mean follow-up was 42.6 ± 2.7 months (38 to 48). The diagnosis was osteoarthritis in 47 patients and rheumatoid arthritis in one patient. There were 44 calf thrombi, four popliteal thrombi but no thrombi in the femoral or iliac regions. Of the 48 patients, 24 were clinically symptomatic and 24 were asymptomatic. Clinical examination was carried out on 41 patients, of whom 37 underwent ascending venography. Seven were evaluated by telephone interview. No patient had the symptoms or signs of recurrent DVT, venous insufficiency in the affected leg, or a history of pulmonary embolism. No patient had been treated for complications of their DVT. Thirty-six of the 37 venographic studies were negative for either old or new DVT in the affected leg. One patient had residual thrombi in the muscular branches of the veins. Our study shows that deep-vein thromboses in the calf after TKA disappear spontaneously with time. No patient developed a recurrent DVT, proximal propagation or embolisation. Treatment of DVT in the calf after TKA should be based on the severity of the symptoms during the immediate postoperative period

Introduction. Bilateral TKA is proven to be safe in a select group of patients. Patients with symptomatic bilateral knee arthritis who are not candidates for simultaneous bilateral TKA are subjected to staged surgery. The main objective of this study is to determine the safe window when second TKA can be performed in patients requiring bilateral TKA. Methods. Retrospective study includes bilateral TKA cases performed in a single institution between 2000–2018. A cohort of simultaneous bilateral TKA (n=2728) was compared to cohort of staged bilateral TKA (n=1660). Outcomes in terms of complications, reoperation, 30 days readmission and cumulative revision rates were compared between the two groups using both non-adjusted and adjusted models. Results. In-hospital complication rates were lower in the staged TKA group in both adjusted model (OR 0.59:0.48 – 0.72)(p <0.001), and unadjusted model (OR 0.54:0.47–0.63)(p<0.001). Although DVT rates were similar between both groups, odds of PE were higher in the simultaneous BTKA group (1.91% vs 0.54%)(p< 0.001). No statistically significant difference was found in reoperation rate between the groups both in the adjusted and unadjusted analyses. All causes revision rate in simultaneous TKA was significantly higher at 6.41% vs 2.35% for the staged TKA gr (OR 0.35 P<0.001). However, revision due to deep infection was higher in the staged group. No difference in complication rate after the 2. nd. surgery was detected when staging TKA was done less than 90 days apart compared to staging > 90 days (80.2% vs 79 %)(p=0.885). Conclusion. This single institution study demonstrates that bilateral TKA performed under the same anesthesia is associated with more complications and revisions than when compared to staged bilateral TKA. Furthermore, performing the second stage TKA under 90 days after the 1. st. TKA was not associated with more complications. Therefore performing simultaneous BTKA, simply for convenience, is not warranted

Deep vein thrombosis remains a significant and common complication following joint replacement and debate exists over which contributing factors are important. This study investigates the effect of a number of variables on the incidence of symptomatic deep vein thrombosis in knee arthroplasty surgery. Data was collected prospectively on 3449 knee replacements including procedure type, tourniquet time, surgeon, patient age, and gender. These variables were assessed by the use of generalised linear modelling against the presence or absence of symptomatic deep vein thrombosis demonstrated on duplex ultrasonography. The overall deep vein thrombosis rate was 1.6%. The only variable which had an association with confirmed symptomatic DVT was operation type with total knee replacements having a higher incidence than unicompartmental knee replacements (2.2% vs 0.3% p=0.0003). Tourniquet time did not exhibit a statistically significant effect (p=0.63) These data show that the DVT rate in unicompartmental knee replacement is statistically significantly lower than that of total knee replacement. They do not support the notion that increased tourniquet time is associated with an increased risk of DVT

Aims

This study aims to determine difference in annual rate of early-onset (≤ 90 days) deep surgical site infection (SSI) following primary total knee arthroplasty (TKA) for osteoarthritis, and to identify risk factors that may be associated with infection.

Background. Total Knee Replacement (TKR) is technically demanding, time consuming and has higher complication rates in super obese (BMI>45) patients. Bariatric surgery can be considered for such patients prior to TKR although its effect on complications is unknown. Methods. All patients who underwent bariatric surgery and a TKR in the NHS in England between 2005 and 2009 were included. Hospital episode statistics data in the form of OPCS, ICD10 codes were used to establish 90-day DVT, PE and mortality rates (inpatient and outpatient). In addition, readmission to orthopaedics, joint revision and ‘return to theatre for infection’ rates were also established. Code strings for each patient were examined in detail to ensure the correct gastric procedures were selected. Fifty-three patients underwent bariatric surgery then TKR (44-1274 days) (group 1). Thirty-one patients underwent TKR then bariatric surgery (33-1398 days) (group 2). Results. In the 53 patients that underwent bariatric surgery first there was 1 DVT, no PE and 1 death at 90 days following knee replacement. There were no orthopaedic readmissions within one year of TKR, no revision at 18 months and no knee washouts for infection. In the 31 patients that underwent TKR first there were no DVT, PE or deaths at 90 days. There were four orthopaedic readmissions (12%) within 30 days of TKR and two infections of the knee replacement. Overall, one-year infection rate and readmission were higher if TKR was performed prior to the bariatric surgery. The statistical analysis is difficult due to small number of patients. Conclusions. This data suggests that timing of bariatric surgery appears to be crucial. Although complication rates appear high in patients who undergo both procedures, performing bariatric surgery first appears to reduce that risk of local complications

Aims

The optimal bearing surface design for medial unicompartmental knee arthroplasty (UKA) remains controversial. The aim of this study was to compare outcomes of fixed-bearing (FB) and mobile-bearing (MB) UKAs from a single high-volume institution.

Aims

The purpose of this study was to compare reoperation and revision rates of double plating (DP), single plating using a lateral locking plate (SP), or distal femoral arthroplasty (DFA) for the treatment of periprosthetic distal femur fractures (PDFFs).

Aims

Periprosthetic fractures (PPFs) around the knee are challenging injuries. This study aims to describe the characteristics of knee PPFs and the impact of patient demographics, fracture types, and management modalities on in-hospital mortality.

We studied a series of Endo-Modell(r) rotating hinge knee replacements (RHKRs) to determine indications, implant survival and complication rates. Case notes were audited for a consecutive series of 129 implants performed between 08/12/2002 and 30/01/2009. Indication for use of RHKR was complex primary arthroplasty in 37.8% and revision in 62.2%. For primary arthroplasty with hinge prosthesis, commonest indications were: collateral ligament insufficiency (44.4%); advanced RA (13.9%); supracondylar fracture (5.6%). Indications for revision RHK arthroplasty were: aseptic loosening (40.4%); ligamentous or soft tissue failure (14.0%); periprosthetic fracture (7%); infection (51%). Infection was proven in 21% with 54% of patients requiring a one stage and 46% two stage revision. For revision cases, 74% of primary prostheses were cruciate retaining PFC (Depuy) and in 5%, the primary was itself an Endo-Modell(r) RHKR. Mean time from index to revision procedures was 6.7 years (range 1 year – 23 years). Complications were: deep infection (6.1%) and non-fatal PE (1%). None developed clinically detectable DVT. Transfusion was required in 29 cases (for such cases, an average 3 units was given). 30-day mortality was 1%. For the revision cases, the average length of hospital admission was 11 days. Mean duration of follow up was 45 months (with a minimum of 21 days and maximum of 92 months). During this time 2 RHKRs failed. A total of 7 patients died during the period from complications unrelated to their surgery. 31 cases were lost to follow up. We conclude that in this series of Endo-Modell(r) rotating hinge knee arthroplasties, results are comparable with similar revision procedures. There was a low rate of prosthesis failure, DVT and PE

Introduction. We examined the effect on blood loss of two standardised intravenous bolus doses of 500 mg of Tranexamic Acid, a fibrinolytic inhibitor that reduces blood loss following Knee Arthroplasty (KA). Materials and Methods. Our study included one hundred consecutive patients undergoing primary cemented KA, who received two standarised bolus doses of 500 mg of Tranexamic Acid. The first dose was administered at induction to anaesthetic and the second dose was administered just before the closure. Data, which included Haemoglobin (Hb), Haematocrit (Hct), Length of Hospital Stay (LOS) and complications, was collected prospectively by an independent observer. Routine blood tests were done on the 1. st. or 2. nd. post-operative day. Results. Out of 100 patients aged from 49 to 92 years old (mean age of 69 years), 39 were male and 48 underwent a right KA. The mean LOS was 4.73 days with a standard deviation (SD) of 3.07 days. The mean drop of Hb was 2.04 g/dl (15.5%) with a SD of 0.89 g/dl (6.2%). The mean drop of Hct was 0.096 (16.7%) with a SD of 0.325 (10.0%). Only 2 patients had developed symptoms of anaemia and were transfused with 2 units of red blood cells each. Ultrasound scan was used to investigate patients with possible Deep Venous Thrombosis (DVT). Indications were calf pain and swelling of the lower limb. 10 patients were investigated, out of which in only 3 patients the diagnosis of DVT was confirmed, whereas in 2 patients DVT could not be excluded because of obesity. Conclusions. We believe that the use of two standardised intravenous bolus doses of 500 mg of Tranexamic Acid reduces peri-operative blood loss, reducing the need for transfusion, without increasing the risk of thromboembolic complications

Introduction. Anterior cruciate ligament (ACL) and multiligament knee (MLK) injuries increase the risk of development of knee osteoarthritis and eventual need for total knee arthroplasty (TKA). There is limited data regarding implant use and outcomes in these patients. The aim of this study was to compare the use of constrained implants and outcomes among patients undergoing TKA with a history of prior knee ligament reconstruction (PKLR) to a matched cohort of patients undergoing TKA with no history of PKLR. Methods. All patients with history of ACL or MLK reconstruction who underwent TKA between 2007–2018 were identified in a single institution registry. A matched cohort was identified based on patient age, body mass index (BMI), sex, and year of surgery. The primary outcome measure was utilization of constrained implants. Secondary outcomes included rates of deep vein thrombosis (DVT), pulmonary embolism (PE), infection, postoperative transfusion, postoperative knee range of motion (ROM), revision surgery, and patient reported outcomes (Knee Injury and Osteoarthritis Outcome Score for joint replacement (KOOS, JR). Results. There were 223 patients who met inclusion criteria (188 patients with prior ACL reconstruction, 35 patients with prior MLK reconstruction). Mean age at the time of TKA was 57.2 years (range 31–88). Mean BMI was 29.7 (range 19.5–55.7). Patients with PKLR had a lower Charleston Comorbidity Index compared to controls (p<0.0001). There was a significantly higher use of constrained implants among patients with PKLR (34.1%) compared to the control group (17.9%) (p<0.001). Subgroup analysis showed a higher use of constrained implants among patients with prior MLK reconstruction (60.0%) compared to ACL reconstruction (29.3%) (p<0.001). Removal of hardware at the time of TKA was performed in 69.8% of patients with PKLR. Mean operative time (p<0.001) and tourniquet time (p<0.001) were longer in patients with PKLR compared to controls. There were no significant differences in rates of DVT, PE, infection, transfusion, postoperative knee ROM, or need for revision surgery (p>0.05). There was no significant difference in preoperative or postoperative KOOS, JR scores between groups (p>0.05). Conclusion. Results of this study suggest a history of PKLR results in an increased utilization of constrained implants but no difference in post-operative knee ROM, patient reported outcomes, or incidence of revision surgery