Mark Clatworthy

Does Computer Assisted Navigation Improve Functional Outcomes and Implant Survivability after Total Knee Arthroplasty

The objective of this study was to determine whether computer assisted navigation in total knee arthroplasty (TKA) improves functional outcomes and implant survivability using data from a large national database. We analysed 9054 primary TKA procedures performed between 2006 and 2012 from the New Zealand National Joint Registry. Functional outcomes were assessed using Oxford Knee Questionnaires at six months and five years. On multivariate analysis, there was no significant difference in mean Oxford Knee Scores between the navigated and non-navigated groups at six months (39.0 vs 38.1, P=0.54) or five years (42.2 vs 42.0, P=0.76). At current follow-up, there was no difference in revision rates between navigated and non-navigated TKA (0.46 vs 0.43 revisions 100 component years, P=0.8).

Applications of computer navigation in sports medicine knee surgery: an evidence-based review

Computer-assisted surgery (CAS) has been investigated in a number of sports medicine procedures in the knee. Current barriers to its widespread introduction include increased costs, duration, and invasiveness of surgery. Randomized trials on the use of CAS in anterior cruciate ligament reconstruction have failed to demonstrate a clinical benefit. Data on CAS use in high tibial osteotomy are more promising; however, long-term studies are lacking. CAS has a number of research applications in knee ligament surgery, and studies continue to explore its use in the treatment of osteochondral lesions. This article reviews the applications of CAS in sports medicine knee surgery and summarizes current literature on clinical outcomes.

The Effect of Medial Tibial Slope on Anterior Tibial Translation and Short-Term ACL Reconstruction Outcome

Background  Increased tibial slope has been shown to be associated with higher anterior cruciate ligament (ACL) reconstruction failure rate. Little is known about the correlation of tibial slope and anterior tibial translation in ACL deficient and reconstructed knees as well as the correlation of tibial slope and ACL reconstruction outcome. Purpose/Hypothesis  The purpose of this study was to investigate the correlation of tibial slope with anterior tibial translation and ACL reconstruction outcome. It is hypothesized that increased medial tibial slope is associated with increased anterior tibial translation in the ACL deficient knee. Medial tibial slope is neither expected to affect anterior tibial translation in the ACL reconstructed knee nor short-term ACL reconstruction outcome. Materials and Methods  A cohort of 104 patients with unilateral isolated ACL deficiency undergoing hamstring ACL reconstruction by a single surgeon between 2002 and 2004 was followed up prospectively. Preoperative data were collected including patient demographics, time to surgery, subjective and objective International Knee Documentation Committee (IKDC) outcome scores, as well as manual maximum anterior tibial translation measured with the KT-1000 measuring instrument. Medial tibial slope was assessed on long lateral X-rays using the method described by Dejour and Bonnin (1994). Intraoperative data were collected including meniscal integrity; postoperative data were collected at 1-year follow-up including manual maximum anterior tibial translation (KT-1000 measured), and subjective and objective IKDC scores. Results  A significant positive correlation was seen between medial tibial slope in ACL deficient knees and KT-1000–measured anterior tibial translation ( r  = 0.24; p  = 0.003). The positive relationship increased when meniscal integrity was factored in ( r  = 0.33; p  < 0.001). No significant correlation was seen between medial or lateral meniscal integrity and KT-1000–measured anterior tibial translation ( r  = −18; p  = 0.06). No significant correlation was seen between KT-1000–measured anterior tibial translation and time to surgery. One year postoperatively, 82 patients were assessed, while 26 patients were lost to follow-up; no significant correlation was found between increased medial tibial slope and poor ACL reconstruction outcome measured by post-ACL reconstruction anterior tibial translation (KT-1000) or subjective and objective IKDC scores. Conclusion  Increased medial tibial slope is associated with increased (KT-1000 measured) anterior tibial translation in ACL deficient knees. No significant correlation is found between increased medial tibial slope and poor short-term ACL reconstruction outcome.

A Prospective Outcome, MRI and Biospy Study of MACI Cartilage Transplantation

Objectives: MACI has been performed by one surgeon. in New Zealand in patients who have failed a microfracture procedure A prospective study with outcome scores, serial MRI’s and biopsies has been performed Method: Fifteen patients have had a MACI since July 2004. All patients have a five year follow up, four a ten year follow up. No patients have been lost to follow up. The mean age is 34 (range 25-45). The mean defect size is 3.76 cm2 (range 2.2 – 6.0 cm2). VAS pain, KOOS score, IKDC subjective score, WOMAC score, SF 36 & Tegner Activity score were collected by a research assistant preoperatively and at 6 months, 1, 2, 3 5 and 10 years. An MRI scan was performed at all time intervals. Biopsies were taken at 3 – 5 years in all patients. Results: All outcome scores and VAS pain scores show a significant improvement post MACI up to two years, a plateau to five years the deteroriation at ten years. There are two failure to date thus survival is 87% at a mean of 8 years. MRI showed restoration of repair tissue with a mean fill of 90% at 2years, 72% at 5 years and 49% at ten years and all patients at ten years had a full thickness defect 86% of patients had bone oedema at 5 years, 100% at 10 years 28% had bone cysts at 5 years, 100% at 10 years All patients have had MACI biopsies. Eleven biopsies show fibrocartilage and four show hyaline like cartilage. Eleven have a normal ICRS arthroscopic score, three a nearly normal score and one abnormal score however 80% have a softer MACI graft than surrounding articular cartilage. Conclusion: Outcome scores are reasonable but are deterioating at 10 years Serial MRI’s show significant graft deterioration, increasing bone oedema and bone cyst formation At rearthroscopy 80% of grafts are soft and 73% of biopsies show fibrocartilage. MACI post microfracture is not the long term solution for isolated chondral defects.

Outcome & Survival Analysis of Conventional Measured Resection, Neutral Alignment Attune TKA vs CAS Anatomic Tibia, Balanced Femur, Constitutional Alignment Attune TKA

Objectives: Arthroplasty knee surgeons have traditionally performed a measured resection technique with a neutral mechanical axis. We have recently developed a new total knee arthroplasty technique whereby the tibia is cut anatomically and the femoral component position is determined using a balanced approach utilizing a computer assisted ligament tension device with aim of restoring constitutional alignment. This study compares the Oxford scores and survival of these two techniques for Attune TKA’s. Method: The New Zealand Joint Registry has requested Oxford Knee Scores at six months on all Attune Total Knee Replacements performed. 1088 scores have been returned. 716 have been performed using a conventional measured resection technique aiming for a neutral mechanical axis. 362 have been performed using the CAS anatomic tibia, balanced femur (ATBF) technique aiming for constitutional alignment. Oxford scores are compared alone and with a multivariate analysis including age, sex, surgeon level, fixed vs mobile, public vs private, operative time and cruciate retaining vs cruciate substituting Results: Mean Oxford Conventional TKA univariate Oxford Score is 38.1 Mean Oxford CAS ATBF TKA univariate Oxford Score is 40.7 p=<0.001 Mean Oxford Conventional TKA multivariate Oxford Score is 36.9 Mean Oxford CAS ATBF TKA multivariate Oxford Score is 39.1 p=<0.001 The CAS ATBF had 10% less poor and fair scores and 15% more excellent scores Non infection conventional TKA has 0.71 failures per 100 component years Non infection CAS ATBF TKA has 0.25 failures per 100 component years. Conclusion: The CAS assisted anatomic tibia balanced femur TKA has a significantly higher Oxford score with a three times lower non infection failure rate at three years

Graft Diameter matters in Hamstring ACL reconstruction

Objective: Recently techniques have been developed to increase graft diameter in hamstring ACL reconstruction with the hope to decrease graft failure. To date there is limited evidence to show that a smaller graft diameter results in a higher ACL failure rate. Method: The factors for failure in 1480 consecutive single surgeon hamstring ACL reconstructions were evaluated prospectively. Patients were followed for 2-15 years. A multivariate analysis was performed which looked at graft size, age, sex, time to surgery, meniscal integrity, meniscal repair and ACL graft placement to determine whether graft diameter matters in determining the failure of hamstring ACL reconstruction. Results: Graft diameters ranged from 6-10 mm. The mean graft diameter for all patients was 7.75 mm. 83 ACL reconstructions failed. The mean size of graft failures was 7.55 mm ACL reconstructions that failed had a significantly smaller hamstring graft diameter p=0.001. The Hazard Ratio for a smaller diameter graft is 0.517 p=<0.0001. For every 1 mm decrease in graft diameter there is a 48.3% higher chance of failure. The multivariate analysis showed a hazard ratio of 0.543 p=0.002. For every 1 mm decrease in graft diameter there is a 45.7% higher chance of failure. Conclusion: Smaller diameter hamstring grafts do have a higher failure rate. Grafts ≤ 7.5 mm had twice the failure rate of grafts ≥8 mm using a multivariate analysis for every 1 mm decrease in graft diameter there is a 45.7% higher chance of failure.

Total Knee Replacement Plus Nonsurgical Treatment Was Better Than Nonsurgical Treatment Alone for Knee Osteoarthritis

Skou ST, Roos EM, Laursen MB, Rathleff MS, Arendt-Nielsen L, Simonsen O, Rasmussen S. A randomized, controlled trial of total knee replacement. N Engl J Med. 2015 Oct 22;373(17):1597-606. ### Question: In patients with knee osteoarthritis, is total knee replacement plus a 12-week nonsurgical treatment program more effective than nonsurgical treatment alone? ### Design: Randomized (allocation concealed), blinded (outcome assessor and statistician), controlled trial with 12 months of follow-up. ### Setting: Aalborg University Hospital, Aalborg, Denmark. ### Patients: 100 patients (mean age, 66 years; 62% women) with radiographically confirmed knee osteoarthritis who were eligible for total knee replacement. Patients with previous total knee replacement on the same knee, those requiring simultaneous total replacement of both knees, and those with severe knee pain in the previous week were excluded. All patients were included in the analysis. ### Intervention: Patients were allocated to total knee replacement plus nonsurgical treatment (n = 50) or nonsurgical treatment alone (n = 50). The total knee replacement procedure followed standard methods using a total cemented prosthesis with patellar resurfacing (NexGen …

Posterolateral Corner Deficiency in Revision ACL Reconstruction

There are many etiologies for failed ACL reconstruction. Failure to recognize and address a posterolateral corner injury may be a predisposing factor. A correct diagnosis requires an accurate history as well as an appreciation of the subtleties of a complete knee examination. If revision surgery is indicated, we prefer an anatomic technique utilizing an Achilles tendon allograft reconstruction of the fibular collateral ligament and posterolateral corner.