Bioabsorbable Versus Titanium Screws in ACL Reconstruction. A Randomised Controlled Trial with 13 years Follow-up

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1 Bioabsorbable Versus Titanium Screws in ACL Reconstruction. A Randomised Controlled Trial with 13 years Follow-up Justin Roe, Keran Sundaraj, Emma Heath, Lucy Salmon, Leo Pinczewski North Sydney Orthopaedic & Sports Medicine Centre The Mater Hospital

2 Financial Disclosure Associate Professor Justin Roe I receive institutional research support from Smith and Nephew and 360 Knee Systems I have received paid speaker fees from Depuy and Smith and Nephew I am unpaid consultant and receive Stock Options in 360 Knee Systems

3 Background & Aim Aperture fixation by interference screws are wellestablished techniques in ACL reconstruction TITANIUM SCREWS disadvantages Graft damage BIOABSORBABLE SCREWS disadvantages Screw breakage MRI artifact Effusions Removal at future surgery Decreased pullout strength The aim of this study was to compare clinical and radiological outcomes of bioabsorbable vs titanium screws in ACL reconstruction at two, five and thirteen years in an randomised controlled trial

4 Methods Inclusion Criteria Primary ACL with hamstring autograft between June 2002 and October 2003 Written informed consent Exclusion Criteria Concurrent significant other ligament injury Significant chondral injury >1/3 meniscectomy Abnormal contralateral knee Seeking compensation Randomisation via sealed envelope, opened at surgery Participants and assessors were blinded to screw type

5 Participant Flow & Demographics Allocated to titanium group N=20 Assessed at 13 years N=18 MRI at 13 years N=13 Assessed for eligibility N=481 Met inclusion criteria and randomised N=40 Allocated to PLLA-HA group N=20 Assessed at 13 years N=17 CT and MRI scan at 13 years N=13 PLLA-HA Group 14 male, 6 female Mean age 33 years 1 contralateral ACL rupture Titanium Group 15 males, 5 female Mean age 29 years 1 contralateral ACL rupture 1 ACL graft rupture

6 Surgical Technique GRAFT 4-strand autologous hamstring FEMORAL TUNNEL Anteromedial portal, 5mm anterior to posterior capsular insertion TIBIAL TUNNEL ACL footprint PLLA SCREW PLLA-HA (75% PLLA + 25% HA; BioRCI-HA, Smith &Nephew Endoscopy) TITANIUM SCREW Titanium RCI; Smith & Nephew Endoscopy

7 PLLA-HA Screw Resorption on MRI no resorption ill defined thread partial screw body complete screw resorption no resorption ill defined thread partial screw body complete screw resorption YEAR 5 YEAR 13 YEAR Tibial Screw 2 YEAR 5 YEAR 13 YEAR Femoral Screw The PLLA-HA group on both tibial and femoral sides showed early evidence of resorption of screw over the first 5 years. By 13 years, there was complete or near complete resorption on MRI

8 Tunnel Volume on MRI Tibial Tunnel Femoral Tunnel p=0.004 p=0.03 p=0.002 p=0.73 p=0.13 p=0.77 Titanium Screw had significantly larger tibial and femoral tunnels at 13 years compared to PLLA-HA screw

9 PLLA-HA Tunnel Volume on CT 13yrs Tibial Tunnel Femoral Tunnel Volume (cm 3 ) Tunnel that is bone (%) Tunnel with cortical margin (%) Screw Resorption 100% 100%

10 CT versus MRI Volume Measures Tibial Volume Femoral Volume Pearson = 0.76, p=0.004 Pearson = 0.79, p=0.002 Tunnel Volume measures on CT and MRI were significantly correlated

11 Clinical and Subjective Outcomes at 13 Years PLLA-HA screw Titanium Screw p value Mean IKDC Score Lysholm Knee Score Strenuous or Very Strenuous Activity 78% 77% 0.64 Return to Sport 83% 82% 0.51 No or mild difficulty kneeling 94% 88% 0.61 No Effusion 93% 100% 0.29 Normal Range of Motion Grade 86% 93% 0.21 Normal Ligament Grade 71% 67% 0.78 Normal Overall IKDC Grade 64% 60% 0.62 No significant difference in subjective or clinical outcomes between screw types

12 Ganglion Femoral Tunnel Tibial Tunnel There was a higher incidence of ganglion/cyst formation in the tibial tunnel in the PLLA group compared to the titanium group at 13yrs

13 Key Findings & Conclusions Clinical and Subjective Outcomes No difference between groups Screw resorption Near complete or complete resorption of BIOHA screw on MRI/CT at 13yrs Tunnel Larger tunnel size in the titanium group at 13yrs Higher % intra-tunnel ganglion formation in the PLLA group at 13 years Limited bone formation over time in both groups Conclusions PLLA-HA screws provides adequate aperture fixation in ACL reconstruction with excellent functional outcomes PLLA-HA screws provide a good alternative to titanium screws, which may aid revision procedures and allow for imaging without artifact, however these will not necessarily convert to bone over a prolonged period