THE KNEE SOCIETY VIRTUAL FELLOWSHIP

LATERAL UKA Less than 1% of all knee arthroplasties Technically more difficult Less reproducible Complex kinematic profile Screw-home mechanism Paucity of literature Scott RD, Orthopedics 2005 Fitz, JBJS-Am 2009 Ashraf et al., JBJS-Br 2002

ISOLATED LATERAL OSTEOARTHRITIS Approximately 10% of OA May be more common Often missed Disease of flexion Sah & Scott, JBJS-Am 2007 Pandit et al., Knee 2009

RADIOGRAPHIC ANALYSIS Weight Bearing Varus Stress 45º Flexed Courtesy of Prof. David Murray Valgus Stress 45º Flexed

LATERAL UKR CURRENT RECOMMENDATION Fixed bearing Monoblock/DCM Same technique as medial UKA Good short results Shakespeare 05/06 50 cases

MATERIALS AND METHODS 132 Lateral UKA (127 patients) 2004-2008, 2 centers Avg. age: 69.5 years (39-97) Avg. weight: 184 lbs (128-280) Avg. BMI: 30.0 kg/m 2 (19-47) Female gender: 70% Berend, Kolczun et al., CORR 2012

INDICATIONS Full thickness loss laterally Maintenance medially on varus stress radiograph No significant radiographic /arthroscopic patellofemoral disease Age, weight, activity, degree of deformity not used as contraindications in any case

VARUS STRESS VIEW 56 KNEES 15º Flexion Varus Load Correction of intra-articular deformity Preservation of medial joint space

DIAGNOSTIC ARTHROSCOPY 76 KNEES 2-3 weeks pre-op 5mm Interview scope Confirm isolated lateral disease

LATERAL UKA Metal-backed Fixed bearing Monoblock/DCM: 90 UKA Modular: 42 UKA All implants cemented

Patellar Tendon Split SURGICAL PEARLS Flexion Extension Preoperative arthroscopy when in doubt Hanging leg position/leg holder Mid-line skin incision Mini-LATERAL parapatellar approach Extramedullary alignment guides Patellar tendon split for vertical tibial resection Balance 2-3mm Lax 90 flexion Tight or 0mm full extension

PATELLAR TENDON SPLIT Trans-patellar tendon approach for vertical tibial resection Allows for proper internal rotation of tibial baseplate in relationship to femoral implant Allows for medial enough resection to reconstruct the entire lateral plateau Enlarges surface area of implant and resection to prevent subsidence and failure

BALANCING Laxity Flexion gap 2-3mm lax Extension gap 0mm

IMPINGEMENT Patellofemoral joint Tibial Implant-Femur

43-YEAR-OLD ACTIVE FEMALE 3 months s/p AKS lateral meniscectomy 2 years s/p lateral UKA

86-YEAR-OLD INACTIVE MALE >10 years pain Multiple medical comorbidities 1 year s/p UKA

DEVICE

RESULTS 19 patients (19 knees) expired before minimum 2-year followup No revisions 13 patients (13 knees) lost before minimum 2-year follow-up Average follow-up: 12.3 months Average KSS Clinical: 92 of 100 Average KSS Pain: 44 of 50 Berend, Kolczun et al., CORR 2012

RESULTS 100 knees (93 living patients) Average follow-up: 39 months 99% implant survival 1 revision at 30 months 2 Reoperations: 1 medial meniscal tear 1 lateral plateau fracture (MVA) 97% free of reoperation Berend, Kolczun et al., CORR 2012

2 Years s/p UKA 2 Weeks s/p MVA 1 Year s/p ORIF

KNEE SOCIETY PAIN AND FUNCTION 50 100 40 46 90 80 88 70 30 60 20 50 40 30 47 10 20 8 10 0 Pre-op Post-op 0 Pre-op Post-op p>0.001 p<0.001

KNEE SOCIETY CLINICAL & RANGE OF MOTION 100 140 90 80 70 94 120 100 115 124 60 50 40 49 80 60 30 40 20 10 20 0 Pre-op Post-op 0 Pre-op Post-op P<0.0001 P<0.05

LATERAL UKA SINGLE SURGEON EXPERIENCE June 2005 Sept. 2010; 98 patients; 104 lateral UKA 102 OA; 2 PTA Mean age: 57 years; BMI: 30.0 kg/m2 Nonmodular, FB, metal backed; lateral parapatellar Mean follow-up: 2.3 years (6w 6.2 yrs) KS Pain: 10 preop to 41.6 postop KS Clinical: 48.8 preop to 89.6 postop KS Function: 53.3 preop to 73.6 postop 2 reoperations: 1 I&D non-healing wound; 1 arthroscopic repair of MMT 2 revisions: 1 to CR-TKA at 16m for femoral loosening; 1 revised elsewhere for pain Berend et al., OCNA 2015

IS LATERAL BETTER THAN MEDIAL?

JIS LATERAL COHORT 104 Lateral UKA (98 patients) 2005-2010 Average Age: 57 years (39-97) Avg. BMI: 30.0 kg/m 2 (19-47) Female gender: 69% Minimum 24 month follow-up Cemented, metal-backed, DCM

INDICATIONS Full thickness loss laterally Maintenance medially on varus stress radiograph No significant radiographic/arthroscopic patellofemoral disease Age, weight, activity, degree of deformity not used as contraindications in any case

JIS MEDIAL COHORT 1000 Medial UKA (808 patients) 2004-2008 Average Age: 63 years (29-91) Avg. BMI: 32.2 kg/m 2 (17-58) Female gender: 56% Minimum 24 month follow-up Cemented, mobile-bearing

ANTEROMEDIAL ARTHRITIS Anatomic Criteria May Expand the Percent of Ideal Candidates > 35% Full Thickness Cartilage Loss Anterior Disease, Preserved Posterior Bone Fully Correctible Full Thickness Lateral Cartilage

JIS: DEMOGRAPHIC & OUTCOME COMPARISON IN MEDIAL VS LATERAL UKA Characteristic Lateral UKA Medial UKA (n=104) (N=1000) P value Age (years) 57 62.8 P<0.05 Body mass index (kg/m 2) 30 32 P<0.05 Follow-up (months) 39 44 NS Knee Society Pain 44 43 NS Knee Society Total 92 90 NS Range of Motion 124 118 P<0.05 Implant Survival 98% 95% 0.040

FIXED LATERAL Utilized MRI imaging and cluster analysis for anatomical sizing and shape Instrumentation adapted from Mobile Bearing Medial IM Linked or EM guides

LATERAL TIBIAL SIZING STUDY 400+ cadavers (MRI database) Virtual resections (4 levels) Standard Horizontal: 7 º posterior, 0 º varus, 4mm below lateral plateau point Vertical: 4mm lateral to eminence point, Plane normal to Cobb Axis 1mm above standard 1mm below standard 2mm below standard

LATERAL TIBIAL SIZING STUDY Shape extraction 50 points around perimeter Clustering Grouped by AP size Averaging 50 points used to find average curve by RMS method 1 average cluster curve for each resection and cluster Cluster curve overlays used to create implant profile sizing rationale 8 Cluster Curves at Standard Resection Level 4 Cluster 2 Curves Overlaid (Anterior Consistent between Levels)

FIXED LATERAL Tibial resection Check in extension that 3-4mm shim and tibial baseplate fit or cut more tibia Femoral alignment EM guide adaptor IM Guide adaptor 0º Varus/Valgus Balance in extension Flexion will be loose Increase slope if tight

FIXED LATERAL Simplified technique Adapted from medial mobile bearing DCM Poly with metal backing Designed to minimize risk of impingement Anatomic size and shape Specifically designed for lateral UKA

LATERAL MOBILE BEARING 100% 20mm movement Mobile bearing ideal 76% 8-year survival Contraindicated 80% 60% 40% 20% 0% All revisions 0 2 4 6 8 10 Gunther, Knee 1996

MOBILE LATERAL High flexion Femur subluxes posteriorly Biconvex tibial insert Domed tibial baseplate Increases entrapment Clinical trial ongoing Normal movement Decreased dislocation Increased flexion Available in Canada Available in US in future

RESULTS OF LATERAL UKA - I Study # Device (Manufacturer) F/U (yrs) Survivorship (# Rev) Scott & Santore, JBJS 1981 12 Brigham I & II (DePuy); all-poly tibia 3.5 (2-6) 83.3% (2) Mallory & Danyi, CORR 1983 4 17 % Polycentric (Stryker); 83% Marmor 5.6 (5-8) 50% (2) (Smith & Nephew); all-poly Marmor, CORR 1984 14 Marmor, cemented, all poly tibia 7.4 (3-10) 85.7% (2) Kozinn et al., J Arth 1989 11 Brigham Mod (DePuy), metal-backed 5.5 (5-6) 100% (0) Magnussen & Bartlett, J Arth 1990 9 PCA (Stryker), cementless, metal-backed (2-3) 100% (0) Christensen, CORR 1991 54 St. Georg Sled (Link), all-poly tibia 3.9 (1-9) 98% (1) Rougraff et al., CORR 1991 14 Compartmental I & II (Zimmer), all-poly 6.5 (1-14) 92.9% (1) tibia Scott et al., CORR 1991 12 Brigham I & II (Stryker); all-poly (8-12) 83.3% (2) Capra & Fehring, J Arth 1992 4 8 Marmor (Richards) Compartmental II 11.1 (8-14) 6.3 (4-11) 100% (0) 100% (0) Heck et al., CORR 1993 39 Marmor (Smith & Nephew), 6 (max 15) 97.4% (1) Compartmental I & II Swank et al., CORR 1993 7 5 Fibermesh (Zimmer); 2 Microloc (DePuy); 5.5 (4-8) 87.8% (na) cementless & cemented Witvoët et al., Rev Chir 1993 135 Lotus (GUEPAR) 4.5 81% (26) Lewold et al., J Arth 1995 36 Oxford (Biomet), mobile-bearing 6 (1-10) 86.1% (5) Cartier et al., J Arth 1996 7 Marmor, all poly tibia 12 (10-18) 85% (NA) Gunther et al., Knee 1996 53 Oxford, mobile-bearing 5 (3-10) 82% (11) Tabor & Tabor, J Arth 1998 6 Marmor-style, all-poly tibia 9.7 (5-20) 66.7% (2) Ohdera et al., J Arth 2001 18 4 different designs 8.3 (5-16) 88.9% (2) Argenson et al., JBJS 2002 15 Miller-Galante (Zimmer), metal-backed 5.5 (3-9) 93% (1) Ashraf et al., JBJS Br 2002 83 St. Georg Sled (Link), all poly tibia 9 (2-21) 74% (15)

RESULTS OF LATERAL UKA - II Study # Device (Manufacturer) F/U (yrs) Survivorship (# Rev) Keblish & Briard, J Arth 2004 19 LCS (DePuy), mobile-bearing 11 (5-19) 84.2% (3) Saxler et al., Knee 2004 46 AMC Uniglide (Corin), mobile-bearing 5.5 (2-13) 89% (5) O Rourke et al., CORR 2005 14 Marmor, all-poly tibia 24 (17-28) 72% (2) Pennington et al., J Arth 2006 29 Miller-Galante (Zimmer), cemented 12.4 (3-16) 100% (0) Cartier et al., Orthopedics 2007 30 age <60, Genesis (Smith & Nephew); 20% (5-14) 88% at 12 years uncemented Forster et al., KSSTA 2007 13 17 Preservation (DePuy), mobile-bearing Preservation, all-poly fixed bearing 2 2 77% (3) 100% (0) Sah et al., JBJS 2007 49 4 different designs 5.2 (2-14) 100% (0) Argenson et al., CORR 2008 38 4 different designs 12.6 (3-23) 84% (5) Bertani et al., Rev Chir 2008 35 4 different designs 9 (2-22) 85.7% (5) Lustig et al., OTSR 2009 60 HLS Evolution (Tornier), all-poly tibia 5.2 (2-13) 98.3% Pandit et al., Knee 2010 53 65 101 Oxford I&II (Biomet), mobile-bearing Oxford III flat tibia, mobile-bearing Oxford III domed tibia, mobile-bearing 5.2 4.7 (3-9) 2.3 (1-4) 82% at 4 years (11) 91% at 4 years (9) 98% at 4 years (1) John et al., Int Orthop 2011 9 Miller-Galante, metal-backed 10.8 (2-16) 44.4% (5) Lustig et al., J Arth 2011 54 HLS Evolution, all-poly tibia 8.4 (5-16) 98.1% (1) Berend et al., CORR 2012 100 Vanguard M (Biomet), metal-backed 3.3 (2-7) 99% (1) Heyse et al., Knee 2012 50 Genesis (now Accuris; Smith & Nephew), 20 10.8 (5-16) 94.0% (3) uncemented, 23 all-poly Lustig et al., CORR 2012 13 All post-traumatic; 6 HLS Evolution all-poly; 2 Marmor II (Richards) metal-backed; 5 Miller- Galante metal-backed 10.2 (3-22) 92.3% (1)

RESULTS OF LATERAL UKA - III Study # Device (Manufacturer) F/U (yrs) Survivorship (# Revisions) Panni et al., KSSTA 2012 9 Zimmer High Flex (Zimmer) 4.5 (3-6) 100% (0) Schelfaut et al., KSSTA 2013 25 Oxford III domed mobile-bearing Min 1 96% (1) Streit et al., JBJS Br 2012 50 Oxford III domed mobile-bearing 3 (2-4) 94% (3) Xing et al., JKS 2012 31 Preservation (DePuy) 4.5 (2-6) 100% (0) Altuntas et al., Knee 2013 64 Oxford III domed mobile-bearing 3.2 (2-5) 96.9% (2) Sebilo et al., OTSR 2013 82 Implants from 30 companies 5.2 (<1-23) 84% at 10 y Thompson et al., J Arth 2013 30 Miller-Galante, Zimmer ZUK, Smith & Nephew Journey, Mako 2 96.4% Marson et al., EurJOST 2014 15 12 Oxford domed mobile-bearing; Zimmer High-flex fixed-bearing 2.9 (1-4) 2.7 (1-6) 93.3% (1) 100% (0) Smith et al., Knee 2014 101 AMC Uniglide fixed-bearing (Corin) 3.9 98.7% at 2 y 95.5% at 5 y Walker et al., Int Orth 2014 22 Oxford III domed mobile-bearing 1.8 96% at 2 y (1) Weston-Simons et al., Knee 2014 265 Oxford III domed mobile-bearing 4 (0.5-8.3) 92.1% at 8 y (4) Berend et al., OCNA 2015 104 Vanguard M fixed-bearing 2.3 (<1-6.2) 98.1% (2) Demange et al., Int Orth 2015 33 19 iuni G1 (ConfroMIS) Miller-Galante 2-4.4 6.3 (2-9) 97% at 3.1 y (2) 85% at 2.8 y (3)

SYSTEMATIC REVIEW OF MEDIAL VS. LATERAL SURVIVORSHIP IN UKA 96 eligible studies 57 cohort studies and 1 registry with medial UKA survivorship 15 cohort studies and 1 registry with lateral UKA survivorship 19 cohort studies with combined survivorship 7 registry studies with combined survivorship Van der List et al., Knee 2015

Medial UKA Lateral UKA Studies combining medial and lateral Registries combining medial and lateral Van der List et al., Knee 2015

MEAN SURVIVORSHIP OF MEDIAL AND LATERAL UKA Survivorship 5 year 10 year 15 year 20 year 25 year Medial 93.9 91.7 88.9 84.7 80.0 a Lateral 93.2 91.4 89.4 Combined 92.8 88.6 84.1 82.7 b 72.0 a Studies combined 94.3 90.5 87.0 82.7 b 72.0 a Registries combined 91.7 84.1 69.6 a Medial vs. Lateral P=0.717 P=0.887 P=0.913 Cohort vs Registries P=0.133 p=0.015 a Only one study reported survivorship at this follow-up. b Only three studies reported survivorship at this follow-up. Van der List et al., Knee 2015

RETURN TO SPORTS AND RECREATIONAL ACTIVITY AFTER LATERAL UKA 45 patients; 45 lateral UKA, domed mobile-bearing Gender: 26 female / 19 male Mean age: 61 years (36-81) Mean BMI: 27 kg/m 2 (21-42) Mean follow-up: 3 years (2-4.3) Active in 1 sport: 42 of 45 (93%) before onset of symptoms 43 of 45 (96%) after lateral UKA with 98% returning Return to activity after surgery: 25 patients (56%) within 3 months 35 patients (78%) within 6 months 10 patients (22%) >6 months or remained inactive Walker et al., KSSTA 2015

INDIVIDUAL SPORTS DISCIPLINES BEFORE AND AFTER LATERAL UKA (N=45) Sport # Before # After Difference Biking 27 33 +22% Hiking 22 18-18% Long walks 22 20-9% Nordic walking 11 11 ±0% Fitness / weight-training 9 17 +88% Swimming 9 15 +67% Downhill skiing 8 0-100%* Jogging 6 3-50% Soccer 6 0-100%* Tennis 5 0-100%* Aqua-aerobic 4 8 +100% Cross-country skiing 4 1-75% Aerobics 4 9 +125% *Indicate statistical significant p<0.05 Walker et al., KSSTA 2015

SF-36 PATIENTS AFTER LATERAL UKA VS HEALTHY VS OA * * * * * * * * *Indicate statistical significant p<0.05 Walker et al., KSSTA 2015

SF-36 PATIENTS AFTER LATERAL UKA VS HEALTHY VS OA ** *Indicate statistical significant p<0.05 Walker et al., KSSTA 2015

TAKE HOME MESSAGE The lateral parapatellar approach is safe and effective No intraoperative changes in plan Indications based on anatomic criteria Stress radiographs Diagnostic arthroscopy 90% survivorship at 15 years 98% of patients return to sports and recreational activity after lateral UKA