Results of Cemented vs Cementless Primary Total Knee Arthroplasty Using the Same Implant Design

Accepted Manuscript Results of Cemented versus Cementless Primary Total Knee Arthroplasty Using the Same Implant Design Adam J. Miller, BS, Jeffrey Stimac, MD, Langan S. Smith, BS, Anthony Feher, MD, Madhusudhan Yakkanti, MD, Arthur L. Malkani, MD PII:

S0883-5403(17)31053-7

DOI:

10.1016/j.arth.2017.11.048

Reference:

YARTH 56255

To appear in:

The Journal of Arthroplasty

Received Date: 19 September 2017 Revised Date:

13 November 2017

Accepted Date: 17 November 2017

Please cite this article as: Miller AJ, Stimac J, Smith LS, Feher A, Yakkanti M, Malkani AL, Results of Cemented versus Cementless Primary Total Knee Arthroplasty Using the Same Implant Design, The Journal of Arthroplasty (2017), doi: 10.1016/j.arth.2017.11.048. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Adam J. Miller, BS University of Louisville School of Medicine 500 S Preston Street Louisville, KY 40204, USA 440-382-9521 phone [email protected]

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Jeffrey Stimac, MD KentuckyOne Health Medical Group 201 Abraham Flexner Way, Suite 100 Louisville, KY 40202, USA [email protected]

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Results of Cemented versus Cementless Primary Total Knee Arthroplasty Using the Same Implant Design

Langan S. Smith, BS KentuckyOne Health Medical Group 201 Abraham Flexner Way, Suite 100 Louisville, KY 40202, USA [email protected]

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Anthony Feher, MD Franciscan Health Total Joint Reconstruction 12188-B North Meridian St. Suite 250 Carmel, IN 46032, USA [email protected]

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Madhusudhan Yakkanti, MD Louisville Orthopaedic Clinic 4130 Dutchman's Lane Louisville, KY 40207, USA [email protected]

Arthur L. Malkani, MD (Corresponding Author) University of Louisville Adult Reconstruction Program 550 S. Jackson Street, 1st floor, ACB Louisville, KY 40202, USA 502-852-6902 phone 502-587-0860 fax [email protected]

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Results of Cemented versus Cementless Primary Total Knee Arthroplasty Using the Same Implant Design

ABSTRACT

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BACKROUND: Although cemented total knee arthroplasty (TKA) continues to be the gold standard, there are patient populations with higher failure rates with cemented TKAs such as the obese, morbidly obese, and younger active males. Cementless TKA usage continues to increase due to the potential benefits of long term biologic fixation similar to the rise in cementless THA. The purpose of this study was to evaluate the clinical and radiographic results of cementless TKA using a novel highly porous cementless tibial baseplate.

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METHODS: This was a retrospective matched case control of 400 primary TKAs comparing cementless versus cemented TKAs using the same implant design (Stryker Triathlon, Stryker Inc., Mahwah, NJ). 200 patients with a mean age of 64 years (range: 42 to 88 yrs) and BMI of 33.9 (range: 19.7 to 57.1) were matched to 200 primary cemented TKA patients with a mean age of 64 (range: 43 to 87 yrs) and BMI of 33.1 (range 22.2 to 53.2). The mean follow up in the cementless group was 2.4 years (range 2 to 3.5 yrs) and the cemented group 5.3 yrs (range 2 to 10.9 yrs). Clinical and radiographic analyses were evaluated. Statistical analysis was performed using Microsoft Excel Version 15.21.1.

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RESULTS: There was no statistical difference in age, BMI, and pre-op KSS scores between the two groups (p=0.22; p= 0.82; p=0.43). Patients in both groups had a similar incidence of postoperative complications (p =0.90). Cementless group had 7 revisions with one aseptic loosening of the tibial component (0.5%). Cementless tibial baseplates demonstrated areas of increased bone density at the pegs of the tibial baseplate. The cemented group had 8 total revisions with 5 cases of aseptic loosening (2.5%).

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CONCLUSIONS: Early results of cementless TKA using a highly porous tibial baseplate designed with a keel and four pegs appear promising with one case of aseptic loosening at minimum two year follow up. As the demographics of patients undergoing TKA change to include younger, obese, and more active patients, along with increased life expectancy, the use of a highly porous cementless tibial baseplate maybe be beneficial in providing long term durable biologic fixation similar to the success of cementless THA.

KEYWORDS: Primary TKA; cementless; cemented; outcomes

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INTRODUCTION Cemented TKA continues to be the gold standard for primary TKA. However, patient demographics are changing to include younger, obese, and more active patients [1-3]. Cemented

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TKAs have demonstrated higher failure rates in certain groups such as obese and younger

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patients [4-6]. This poses a challenge to orthopedic surgeons as the largest growth rate for

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prospective TKAs is occurring in the <65 year old patient population. The <65 group is

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expected to represent the majority (>50%) of the anticipated primary TKA burden between 2010

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to 2030 [1]. Life expectancy has also increased creating further need for implants to provide

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more durable long term fixation similar to the success of cementless total hip arthroplasty [6-8].

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The past results of cementless TKA have not been favorable due to multiple reasons including patch porous coating, poor tibial locking mechanisms, and use of first generation

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polyethylene leading to osteolysis with migration of particles through screw holes [9, 10]. These

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earlier cementless TKA design iterations were unsuccessful and suffered from a variety of

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setbacks. Many of these earlier cementless designs did not offer adequate mechanical fixation

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for immediate implant stability irrespective of the complications leading to osteolysis [11]. With

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an understanding of these failure mechanisms and advances in biomaterials, most of the earlier

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design flaws have been corrected leading to improved survivorship of cementless TKA implants

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(Table 1). Given the success of cementless THA and the increased demands placed on current

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cemented TKA designs due to younger and more active patients and greater life expectancy, the

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use of cementless TKA needs to be further evaluated. The purpose of this study was to compare

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the results of cementless TKA using a novel highly porous tibial baseplate with a keel and 4 pegs

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to a cemented TKA using the same kinematically designed total knee implant.

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METHODS AND MATERIALS This was a retrospective matched case control study performed at the same institution with IRB approval. 200 cementless TKAs (Stryker Triathlon, Stryker Inc., Mahwah, NJ)

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performed between June 2013 and September 2014 using a highly porous tibial baseplate with a

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keel and 4 pegs were reviewed. These were compared to a matched cohort using a cemented

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TKA with the same kinematic design (Stryker Triathlon, Stryker Inc., Mahwah, NJ) from a

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prospective total joint registry. The cementless group consisted of 125 females and 74 males

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with an average age of 64 years (42 to 88 yrs), average BMI 33.9 (19.7 to 57), and a mean follow

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up of 2.4yrs (2 to 3.5 yrs). The matched cohort consisted of 200 cemented TKAs with 125

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females and 74 males with an average age of 64 years (47 to 87 yrs), average BMI 33 (range 22

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to 53) with a mean follow up of 5.3 yrs (2 to 10.9 yrs).

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All primary cementless knee arthroplasties were performed using a parapatellar or subvastus approach and a posterior stabilized Stryker Triathlon Tritanium™ tibial baseplate

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along with a cementless peri-apatite coated femoral component, a cementless patella component

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and cross-linked polyethylene liner (Fig 1.). The cemented group consisted of a posterior

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stabilized or cruciate retaining Stryker Triathlon™ total knee with a cemented all polyethylene

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patella component. The cementless, screwless, tibial baseplate was developed from pure

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titanium powder using additive manufacturing technology which can optimize porosity for

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ingrowth and provide solid material for strength in addition to manufacturing complex

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geometries. Mechanical testing of this cementless tibial baseplate demonstrated excellent

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resistance to lift off [42].

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The cementless group received a peri-apatite coated cementless femoral component in all

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cases, along with a cementless patellar component. All components implanted in the cohort were

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cemented including the use of an all polyethylene cemented patella component. Most of the

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cemented total knees were performed prior to the introduction of the highly porous tibial

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baseplate. The selection criteria for cementless TKA was based on the bone quality. Patients

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with adequate bone quality at the periphery or rim of the tibial metaphysis were selected for

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cementless fixation. The selection process was consistent and performed by the same surgeon.

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The same anesthesia and postoperative care protocol were used in both groups including regional

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anesthesia with a combined femoral and sciatic nerve block along with IV sedation or general

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anesthesia. In each case, a pneumatic tourniquet was used and postoperative drains were placed

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prior to closure. The same postoperative physical therapy protocol was also used in both groups

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which consisted of immediate weight bearing with passive and active motion exercises. All

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patients received the same pre-operative antibiotic and postoperative VTE prophylaxis protocol.

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Both cohorts were analyzed for primary outcome measures along with pre and postoperative range of motion, pre- and postoperative Knee Society Scores (KSS), and medical

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or surgical complications. Radiographs were obtained at follow up visits to evaluate signs of

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progressive radiolucent lines, osteolysis, component loosening, malalignment, and subsidence

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(Figure 2). Analysis of the study group and the matched cohort was performed using Microsoft

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Excel version 15.21.1. Two-tailed independent t test was used for continuous variables with

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normal distribution. Chi Square analysis was used to compare categorical variables. Statistical

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significance was defined as p < 0.05.

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RESULTS:

400 primary total knee procedures were reviewed in this study consisting of 200 cementless TKAs matched to 200 cemented TKAs with the same kinematically designed Stryker

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Triathlon total knee implant. There were no statistical differences in age, body mass index, and

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pre-operative KSS between the two matched cohorts (p=0.22; p= 0.82; p=0.43, Table 1). The

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cementless group had a slight improved 2 year KSS functional scores compared to cemented (76

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± 20.4 for cementless and 70.2 ± 22.3 for cemented, p=0.016). KSS knee scores were also

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somewhat improved in the cementless group compared to the cemented group (94.1 ± 6.2 in

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cementless and 91.5 ± 9.8 in cemented (p=0.007, Table 3).

Each group had similar improvements in Knee Society Scores, 53.8 ± 13.8 (Range: 9 to

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80) in the cementless group and 52.4 ± 16.7 (range: 0 to 81) in the cemented group (p=0.47).

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Cemented and cementless groups had similar postoperative knee extension of 0.23 ± 1.7 degrees

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and 0.11 ± 0.9 respectively (p=0.385). The cementless group demonstrated slight improvement

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in postoperative knee flexion compared to the cemented cohort, 119.4 ± 7.0 vs. 116.4 ± 7.8

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(p=0.003).

Both groups had similar rates of failure leading to revision (8 cemented vs. 7 cementless,

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p=0.069). There was one case of aseptic tibial component loosening in the cementless group

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(0.5%) whereas there were 5 cases of aseptic loosening in the cemented cohort (2.5%). Though

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there were more cases of aseptic loosening in the cemented group, this comparison was not

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significant, p=0.2 (Table 4). The cementless group had 7 total revisions; one revision for flexion

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instability treated with liner exchange, one extensor mechanism rupture treated with liner

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exchange and quad repair, one postoperative infection treated with liner exchange and I&D, one

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recurrent patellar dislocation with liner exchange and quad tendon repair, and one case where the

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patella was not resurfaced during the index procedure which subsequently developed

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patellofemoral arthrosis requiring patella arthroplasty. Except for the one aseptic tibial

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component loosening in the cementless group, all other cementless cases demonstrated

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radiographic dense spot welding or increased bone density primarily around the four tibial pegs.

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There were no cases of aseptic loosening in either the cementless femoral or patella components. The cemented group had 8 total revisions, including five cases of aseptic loosening; one

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patellar loosening, two tibial component loosening, and two both femoral and tibial component

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failures. There were two revisions due to flexion instability treated with conversion to a posterior

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stabilized design, and one case of liner exchange with irrigation and debridement performed for a

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traumatic arthrotomy after a postoperative fall. There were no postoperative infections in the

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cemented group and one infection in the cementless group. Each group had a similar incidence

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of medical and surgical postoperative complications.

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DISCUSSION:

Total knee arthroplasty is the treatment of choice for end stage osteoarthritic knee disease when all non-operative methods have failed. The results of cemented Stryker Triathlon TKA

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have demonstrated excellent results in a prior study [12]. However, as the patient population

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receiving TKA continues to evolve to include obese, younger and more active patients who are

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also living longer, surgeons are faced with the challenge of providing durable long term implant

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fixation. Gioe et al. in a study from 1991 to 2002 on 5760 primary TKA’s attributed 40% of

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their revisions due to aseptic loosening [13]. Younger patients with active lifestyles and obese

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patients pose a challenge to the gold standard of cemented TKA due to concerns of aseptic

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loosening [8]. Aseptic loosening is one of most common etiology of failure with cemented TKA

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designs faced by younger and heavier patients [14-16]. Abdel et al. in a review of cemented

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TKA’s demonstrated increased failure due to aseptic loosening in obese patients despite well

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aligned knees [4]. Bagsby et al. demonstrated higher failure rates with cemented primary TKA

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compared to cementless TKA in the morbidly obese, 89% survivorship versus 99% respectively

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[17]. Higher failures rates have also been demonstrated in younger patients undergoing primary

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TKA [18]. Gioe et al. showed cemented TKA survival rate at 85% in a cohort (n = 1047) of

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patients less than 55 years old over a 14 year period [18]. Meehan et al. demonstrated that the

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risk of revision surgery due to aseptic loosening in cemented primary TKA at one year

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postoperatively in patients <50 years old was 4.7x greater than that of a >65 year old cohort [16].

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A Kaplan-Meier survivorship analysis from McCalden 2013 showed primary cemented TKA

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patients under age 55 with significantly higher rates of revision due to aseptic loosening at both 5

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and 10 years post operatively compared to cementless TKA.

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Given the success of cementless THA, there has been an increased interest in the use of cementless TKA to provide to same benefits of biologic fixation over mechanical cement

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fixation for long term durability. Initial cementless TKA implants however suffered from design

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flaws including poor patch porous coatings, poor tibial locking mechanisms and use of first

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generation polyethylene that led to increased wear and osteolysis with poor outcomes [8, 10, 19].

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Ritter et al. looked at 73 cementless knees from 1984 to 1986 and demonstrated that many of the

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early cases of cementless TKA failures were due to the metal backed patella [20]. 12 of the 15

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failures leading to revision in their series were due to patellar component failure with an overall

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76.4% survivorship at 20 years. The survivorship of the cementless femoral component was

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96.8%. Cementless femoral components have demonstrated excellent survivorship over the long

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term in many series [4, 21, 22]. Many of the early cementless patella component failures

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discouraged orthopedic surgeons away from the use of cementless TKA implants. These early

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patellar design failures have been addressed through numerous improvements including the use

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of thicker, current generation polyethylene, reduction in sharp metal boarders and a higher

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degree of conformity which have led to highly favorable outcomes without the osteolysis and

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accelerated wear noted in first generation designs.[23-26].

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Another area of early design failure of cementless TKA was noted in the higher failure rates of cementless tibial baseplates. Initial cementless tibial baseplate designs demonstrated

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increased incidence of progressive radiolucent lines at the implant/bone interface leading to

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aseptic loosening and subsequent component failure [27, 28]. In all likelihood, initial design

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cementless tibial baseplates did not provide adequate immediate implant stability critical for

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successful biologic ingrowth [29]. Dunbar et al. using radiosterometric analysis (RSA)

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demonstrated that immediate rigid implant stability is essential for successful long term

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biological fixation in a study of cementless TKA [30].

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Despite the initial setbacks in early cementless tibial component designs, these design flaws have mostly been addressed leading to a reevaluation of cementless TKA. Harwin et al. in

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a review of a cementless modern design TKA with peri-apatite coating to improve the potential

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of biologic fixation along with screw fixation on the tibial baseplate to provide immediate rigid

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fixation demonstrated 99% survivorship at an average of 4 years follow up [19]. Beaupre et al.

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in a randomized control trial evaluated a modern design cementless tibial component coated with

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hydroxyapatite versus a cemented tibial baseplate with the same design at 5 years and

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demonstrated equivalent outcomes [31]. Cross et al. reviewed a cohort of 1000 patients who

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received a hydroxyapatite coated cementless TKA implants with a survivorship of 99% at 10

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years with aseptic loosening as the endpoint [32]. Bagsby et al. demonstrated 99% survivorship

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at 3.6 years with cementless TKA compared to 89% survivorship with cemented TKA in the

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morbidly obese patient [17]. Several other studies have demonstrated improved survivorship of

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cementless TKA compared to the results of earlier cementless designs [33, 34].

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Due to the challenge of obtaining rigid fixation in early cementless design, adjunctive fixation mechanisms were utilized in earlier designs [3]. Screws were used in tibial baseplates to

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help insure initial stability of the implant to increase the probability of adequate biological

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fixation [36]. However tibial screws served as a conduit for osteolysis via formation channels

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for debris [3, 11]. Holloway et al. showed reliable fixation with screwless cementless tibial

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baseplates at an average of 7.6 years follow up [37]. Other studies have also demonstrated no

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advantage to using tibial baseplate with screws versus no screws [38, 39].

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With advances in technology, new implants have been developed using highly porous components which have obviated the need for adjunct tibial baseplate screw fixation to provide

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immediate implant stability [9, 40, 41]. The cementless tibial baseplate used in this study was

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developed using additive manufacturing 3D printed technology with a keel and four pegs

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designed to provide immediate implant stability [42]. Nam et al. in a similar study comparing

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cementless versus cemented total knee implants demonstrated no difference in blood loss and

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change in hemoglobin but did show decreased operative time in the cementless group. [41].

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In our study, at an average follow up of 2.4 years following TKA using a cementless

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highly porous tibial baseplate, we demonstrated a failure rate due to aseptic loosening of 0.5%.

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The matched cemented cohort used in this study with the same implant design had an aseptic

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failure rate of 2.5%, p= 0.09. Given the history of cementless THA, once biological fixation is

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achieved with cementless TKA, in all probability it should remain durable over the long term.

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Radiographic analysis of the cementless tibial baseplate used in this study demonstrated

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areas of dense bone ingrowth or spot welds primarily at the pegs similar to the areas of bone

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density noted at the screws sites with cementless THA [43]. It is difficult to quantify the amount

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or extent of biological fixation in cementless implants with plain radiographs. Future studies

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using micro CT or extreme CT scans would help quantify the exact location and extent of

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ingrowth in these highly porous implants [44]. Some of the strengths of this study include the use

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of the same kinematically designed TKA implant at the same institution along with the same

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anesthesia and postoperative therapy protocol with the cemented cohort matched from the same

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prospective database.

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Given the higher failure rates of cemented TKA in younger, active, and obese patients

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along with increased life expectancy, there has been an impetus towards the use of cementless

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TKA with the potential of long term durable biological fixation similar to the history and

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evolution of cementless THA use in North America. The results of our study using a highly

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porous tibial baseplate with a keel and four pegs designed for immediately implant stability

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demonstrated excellent short term results and a failure incidence due to aseptic loosening

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equivalent or somewhat better compared to a kinematically designed similar cemented implant.

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Many of the early design flaws of cementless TKA leading to increased wear, osteolysis and

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loosening have been addressed especially with current generation polyethylene and improved

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fixation methods using highly porous implants. Based on our study, young active patients and

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obese patients who place greater demands and stress at the bone implant interface may benefit

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from the use of cementless TKA to obtain the benefits of durable long term biologic fixation.

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Although the early results of this study of cementless TKA is encouraging, additional data is

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required to determine if the benefits of biologic fixation using a highly porous, current design

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cementless TKA can be realized over the long term similar to the history and success of

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cementless THA.

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Aprato, A., et al., Cementless total knee arthroplasty. Ann Transl Med, 2016. 4(7): p. 129. Lass, R., et al., Comparison of cementless and hybrid cemented total knee arthroplasty. Orthopedics, 2013. 36(4): p. e420-7. Hedley, A.K., Minimum 5-Year Results With Duracon Press-Fit Metal-Backed Patellae. Am J Orthop (Belle Mead NJ), 2016. 45(2): p. 61-5. Garcia, R.M., M.J. Kraay, and V.M. Goldberg, Isolated all-polyethylene patellar revisions for metal-backed patellar failure. Clin Orthop Relat Res, 2008. 466(11): p. 2784-9. Kraay, M.J., et al., Outcome of metal-backed cementless patellar components: the effect of implant design. Clin Orthop Relat Res, 2001(392): p. 239-44. Nodzo, S.R., et al., Short Term Outcomes of a Hydroxyapatite Coated Metal Backed Patella. J Arthroplasty, 2015. 30(8): p. 1339-43. Rand, J.A., Cement or cementless fixation in total knee arthroplasty? Clin Orthop Relat Res, 1991(273): p. 52-62. Rosenberg, A.G., R.M. Barden, and J.O. Galante, Cemented and ingrowth fixation of the Miller-Galante prosthesis. Clinical and roentgenographic comparison after three- to sixyear follow-up studies. Clin Orthop Relat Res, 1990(260): p. 71-9. Matassi, F., et al., Cemented versus cementless fixation in total knee arthroplasty. Joints, 2013. 1(3): p. 121-5. Dunbar, M.J., et al., Fixation of a trabecular metal knee arthroplasty component. A prospective randomized study. J Bone Joint Surg Am, 2009. 91(7): p. 1578-86. Beaupre, L.A., et al., Hydroxyapatite-coated tibial implants compared with cemented tibial fixation in primary total knee arthroplasty. A randomized trial of outcomes at five years. J Bone Joint Surg Am, 2007. 89(10): p. 2204-11. Cross, M.J. and E.N. Parish, A hydroxyapatite-coated total knee replacement: prospective analysis of 1000 patients. J Bone Joint Surg Br, 2005. 87(8): p. 1073-6. Epinette, J.A. and M.T. Manley, Hydroxyapatite-coated total knee replacement: clinical experience at 10 to 15 years. J Bone Joint Surg Br, 2007. 89(1): p. 34-8. Kim, Y.H., et al., Cementless and cemented total knee arthroplasty in patients younger than fifty five years. Which is better? Int Orthop, 2014. 38(2): p. 297-303. Berger, R.A., et al., Long-term followup of the Miller-Galante total knee replacement. Clin Orthop Relat Res, 2001(388): p. 58-67. Whiteside, L.A., Four screws for fixation of the tibial component in cementless total knee arthroplasty. Clin Orthop Relat Res, 1994(299): p. 72-6. Holloway, I.P., et al., Tibial fixation without screws in cementless knee arthroplasty. J Arthroplasty, 2010. 25(1): p. 46-51. Ferguson, R.P., M.G. Friederichs, and A.A. Hofmann, Comparison of screw and screwless fixation in cementless total knee arthroplasty. Orthopedics, 2008. 31(2): p. 127. Schepers, A., L. Cullingworth, and D.R. van der Jagt, A prospective randomized clinical trial comparing tibial baseplate fixation with or without screws in total knee arthroplasty: a radiographic evaluation. J Arthroplasty, 2012. 27(3): p. 454-60. Fricka, K.B., S. Sritulanondha, and C.J. McAsey, To Cement or Not? Two-Year Results of a Prospective, Randomized Study Comparing Cemented Vs. Cementless Total Knee Arthroplasty (TKA). J Arthroplasty, 2015. 30(9 Suppl): p. 55-8.

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Nam, D., et al., Perioperative and Early Postoperative Comparison of a Modern Cemented and Cementless Total Knee Arthroplasty of the Same Design. J Arthroplasty, 2017. Bhimji, S. and R.M. Meneghini, Micromotion of cementless tibial baseplates: keels with adjuvant pegs offer more stability than pegs alone. J Arthroplasty, 2014. 29(7): p. 1503-6. Schmalzried, T.P. and W.H. Harris, The Harris-Galante porous-coated acetabular component with screw fixation. Radiographic analysis of eighty-three primary hip replacements at a minimum of five years. J Bone Joint Surg Am, 1992. 74(8): p. 1130-9. Jones, A.C., et al., Analysis of 3D bone ingrowth into polymer scaffolds via microcomputed tomography imaging. Biomaterials, 2004. 25(20): p. 4947-54.

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Figure Legend

Figure 1: Picture of a cementless, highly porous tibial baseplate

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Figure 2a: A/P, lateral and merchant radiographs of a 67-year-old patient with severe OA of the right knee. Figure 2b: A/P, lateral and merchant radiographs one year postoperative right TKA using highly porous cementless tibial baseplate, HA-coated cementless femoral component and cementless patella component.

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Figure 2c: A/P and lateral radiographs four years following index procedure with a well-functioning and stable implant and no evidence of radiolucent lines.

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Table 1: Cementless TKA Survivorship Studies Length of Follow-up 4 years

Survivorship 99.50%

Design Triathlon

Kwong (2014) Schroder (2001) Khaw (2002) Hofmann (2002) Wantabe (2004) Cross (2005) Hardeman (2007) Tai (2006) Wantabe (2004) Goldber (2004) Kim (2014) Tarkin (2005) Whiteside (2002) Buechel (2002) Ritter (2009)

7 years 10 years 10 years 10 years 13 years 10 years 10 years 12 years 13 years 14 years 17 years 17 years 18 years 20 years 20 years

95.70% 97.10% 95.60% 99.00% 96.70% 99.60% 97.10% 97.50% 96.70% 99.00% 98.90% 97.90% 98.60% 97.70% 96.80%

Nex Gen AGC-2000 PFC Natural Osteonics HA Profix HA Osteonics MG-I Nexgen LCS-RP Ortholoc-I LCS-RP AGC

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Table 2: Patient demographics and outcome variables comparing matched Cementless and Cemented cohorts in total knee arthroplasty.

• •

Left Right

74 (37.0%) 126 (63.0%)

74 (37.0%) 126 (63.0%)

103 (51.5%) 96 (48.0%) 33.9 ± 7.5

68 (49.2%) 70 (51.8%) 33.1 ± 6.5

0.22

27.6 ± 3.5

63.4 ± 23.0

<0.00001

p value 0.82 1

0.904

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BMI Follow-up Time (Mo)

Cemented (n=200) 64.4 ± 8.2

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Cementless (n=200) 64.3 ± 8.3

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Table 3: Comparison of outcome scores in matched Cementless versus Cemented Total Knee Arthroplasty. Cemented TKA 70.2 ± 22.3

35.6 (± 19.8)

26.04 ± 26.6

0.0014

94.1 ± 6.1

91.6 ± 9.8

0.0076

53.8 ± 13.8 13

52.4 ± 16.7

0.385

p-value 0.016

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KSS Function Score Change in Function Score KSS Knee Score Change in Knee Score

Cementless TKA 76.0 ± 20.4

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# of revisions - cemented TKA 5 (2.5%) 0 (0.0%)

1 (0.5%)

0 (0.0%)

0.316

1 (0.5%) 1 (0.5%) 1 (0.5%) 1 (0.5%) 0 (0.0%) 7 (3.5%)

2 (1.0%) 0 (0.0%) 0 (0.0%) 0 (0.0%) 1 (0.5%) 8 (4.0%)

0.562 0.316 0.316 0.316 0.316 0.069

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Aseptic Loosening Infection Extensor Mechanism Rupture Flexion Instability Global Instability Patellar Dislocation Patellofemoral Arthrosis Open Arthrotomy Total # of revisions

# of revisions - cementless TKA 1 (0.5%) 1 (0.5%)

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Table 4: Total Revision stratification comparison in matched Cementless versus Cemented Total Knee Arthroplasty.

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Figure 1: Picture of a cementless, highly porous tibial baseplate

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Figure 2a: A/P, lateral and merchant radiographs of a 67-year-old patient with severe OA of the right knee. Figure 2b: A/P, lateral and merchant radiographs one year postoperative right TKA using highly porous cementless tibial baseplate, HA-coated cementless femoral component and cementless patella component. Figure 2c: A/P and lateral radiographs four years following index procedure with a wellfunctioning and stable implant and no evidence of radiolucent lines.