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Abstract. Approximately 20% of primary and revision Total Knee Arthroplasty (TKA) patients require multiple revisions, which are associated with poor survivorship, with worsening outcomes for subsequent revisions. For revision surgery, either endoprosthetic replacements or metaphyseal sleeves can be used for the repair, however, in cases of severe defects that are deemed “too severe” for reconstruction, endoprosthetic replacement of the affected area is recommended. However, endoprosthetic replacements have been associated with high complication rates (high incidence rates of prosthetic joint infection), while metaphyseal sleeves have a more acceptable complication profile and are therefore preferred. Despite this, no guidance exists as to the maximal limit of bone loss, which is acceptable for the use of metaphyseal sleeves to ensure sufficient axial and rotational stability. Therefore, this study assessed the effect of increasing bone loss on the primary stability of the metaphyseal sleeve in the proximal tibia to determine the maximal bone loss that retains axial and rotational stability comparable to a no defect control. Methods. to determine the pattern of bone loss and the average defect size that corresponds to the clinically defined defect sizes of small, medium and large defects, a series of pre-operative x-rays of patients with who underwent revision TKA were retrospectively analysed. Ten tibiae sawbones were used for the experiment. To prepare the bones, the joint surface was resected the typical resection depth required during a primary TKA (10mm). Each tibia was secured distally in a metal pot with perpendicular screws to ensure rotational and axial fixation to the testing machine. Based on X-ray findings, a fine guide wire was placed 5mm below the cut joint surface in the most medial region of the plateau. Core drills (15mm, 25mm and 35mm) corresponding to small, medium and large defects were passed over the guide wire allowing to act at the centre point, before the bone defect was created. The test was carried out on a control specimen with no defect, and subsequently on a Sawbone with a small, medium or large defect. Sleeves were inserted using the published operative technique, by trained individual using standard instruments supplied by the manufacturers. Standard axial pull-out (0 – 10mm) force and torque (0 – 30°) tests were carried out, recording the force (N) vs. displacement (mm) curves. Results. A circular defect pattern was identified across all defects, with the centre of the defect located 5mm below the medial tibial base plate, and as medial as possible. Unlike with large defects, small and medium sized defects reduced the pull-out force and torque at the bone-implant interface, however, these reductions were not statistically significant when compared to no bony defect. Conclusions. This experimental study demonstrated that up to 35mm radial defects may be an acceptable “critical limit” for bone loss below which metaphyseal sleeve use may still be appropriate. Further clinical assessment may help to confirm the findings of this experimental study. This study is the first in the literature to aim to quantify “critical bone loss” limit in the tibia for revision knee arthroplasty. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_30 | Pages 45 - 45
1 Aug 2013
Mullen M Bell SW Rooney BP Leach WJ
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The number of revision knee arthroplasties performed is projected to rise dramatically in the coming years. Primary knee arthroplasties are also being performed in younger patients increasing the likelihood of multiple revision procedures. Reconstruction can be challenging with bone stock deficiencies and ligament incompetence. The aim of this study was to present our results of revision total knee arthroplasty using metaphyseal sleeve components to aid reconstruction. Sixty seven patients underwent revision total knee arthroplasty between September 2005 and November 2010 using metaphyseal sleeves. There were thirty one male and thirty six female patients. The indication for revision was aseptic loosening in thirty nine, sepsis in fifteen, malalignment in eight and instability in five patients. Thirty four patients had tibial sleeves, thirty patients had both tibial and femoral sleeves and three patients had femoral sleeves during revision. The patients were followed up for a mean of 32 months (Range 12–60) with outcome data collected prospectively. The mean revised oxford knee scores for the patients improved from 15 (Range 2 to 29) preoperatively to 33 (Range 20 to 45) postoperatively. Mean arc of flexion following revision was 87 degrees (Range 55 to 120). Seventy six percent of patients were satisfied or very satisfied with the result of the revision surgery. There have been no radiographic complications specific to the sleeves and no re-operations. There has been one recurrence of infection in a patient revised for sepsis. This has been managed with suppressive antibiotics due to patient co-morbidities. Metaphyseal sleeves are an effective adjunct in revision knee arthroplasty. We have had good results with their use. To our knowledge no larger series has been presented or published


Bone & Joint Research
Vol. 9, Issue 4 | Pages 162 - 172
1 Apr 2020
Xie S Conlisk N Hamilton D Scott C Burnett R Pankaj P

Aims

Metaphyseal tritanium cones can be used to manage the tibial bone loss commonly encountered at revision total knee arthroplasty (rTKA). Tibial stems provide additional fixation and are generally used in combination with cones. The aim of this study was to examine the role of the stems in the overall stability of tibial implants when metaphyseal cones are used for rTKA.

Methods

This computational study investigates whether stems are required to augment metaphyseal cones at rTKA. Three cemented stem scenarios (no stem, 50 mm stem, and 100 mm stem) were investigated with 10 mm-deep uncontained posterior and medial tibial defects using four loading scenarios designed to mimic activities of daily living.