Can tibial tantalum cones eventually eliminate the adjuvant use of metallic augments for AORI type 2B/3 metaphyseal defects??-A novel surgical technique and case series

Are Proud Tibial Cone Constructs an Effective Alternative to Those That are Fully Seated in Revision Total Knee Arthroplasty?

BACKGROUND

This study compared the clinical, radiographic, and patient-reported outcomes between patients treated with the traditional fully seated tibial cone construct and those with the novel proud tibial cone construct in revision total knee arthroplasty (rTKA).

METHODS

This was a retrospective study of 56 adult patients who had a minimum 2-year follow-up and underwent rTKA with either the fully seated (n = 18 knees) or proud (n = 42 knees) tibial cone construct between 2010 and 2020. The electronic medical record was reviewed for demographic, clinical, and radiographic data. Knee Injury and Osteoarthritis Outcome Scores (KOOS) were collected.

RESULTS

All patients had improved mechanical alignment postoperatively regardless of surgical technique. All patients showed good evidence of osseointegration without loss of fixation at the latest follow-up. There were no significant differences in the complication rate or re-revision rate between the groups. KOOS Function in Sport and Recreation (Sport/Rec) scores were significantly higher for patients treated with the fully seated construct (mean 57 [range, 20 to 95] versus 38 [range, 0 to 75], P = .04); however, no significant differences were present for the other KOOS subscales or KOOS Jr.

CONCLUSION

The proud tibial cone construct may be an effective alternative to the fully seated construct in the setting of severe bone loss in rTKA. The proud construct avoids a proximal tibial cut, and thus is a bone-preserving technique that provides good fixation, reduces operative time, prevents potential iatrogenic injuries, decreases the need for tibial augments, saves costs, and improves the ease of restoring joint height.

Does the use of 3D-printed cones give a chance to postpone the use of megaprostheses in patients with large bone defects in the knee joint?

Revision procedures and the resulting bone loss are a big challenge for orthopedic surgeons. Therefore, we checked what functional outcomes that 3D-printed cone augments can offer to patients with bone defects (Anderson Orthopedic Research Institute [AORI] classification type 2B and 3) in the knee and whether the use of cones can delay the necessity to use a megaprotheses. Data from 64 patients (M = 22; W = 42) who underwent total knee arthroplasty (TKA) revision were included in the analysis. The Knee Society Clinical Rating System (KSS) and the range of motion in the knee joint were used for the functional assessment. The mean follow-up was 28 months (range: 18–44 months). The survival rate for aseptic loosening at follow-up was 100%. Infection occurred in two (3.1%) patients. The mean KSS score increased from 12.75 points preoperatively to 66.56 postoperatively (p < 0.001). The mean range of motion in the knee changed from 61.15° preoperatively to 115.93° postoperatively (p < 0.001). 3D-printed cone augments seem to be a good solution for patients requiring a TKA revision procedure. When used in patients with bone defects classified as 2B and 3 (AORI), they can be a good alternative, delaying the need for megaprotheses.

TKA-Revision with maintenance of well-fixed metaphyseal sleeves: Indications and surgical technique

Due to the compromised bone situation revision implants need extended fixation options in order to achieve good long-term survival. Over decades this has been achieved with stems, either cemented or uncemented. In the last decade additional fixation options in terms of cementless metaphyseal sleeves or metaphyseal cones have been introduced and widely accepted. Revision of such implants is challenging, in particular if those porous coated parts are well integrated. Therefore, partial revision leaving the well-fixed parts in place can be an option if the indication is allowing it. This can help to preserve bone. In this study we show 2 cases with metaphyseal sleeves, in which we demonstrate when and how revision can be performed leaving sleeves in place. Meticulous pre-Op analysis of the failure mechanism is mandatory to find those few cases in which a partial revision can be recommended. In our cases, it was one patient with persistent tibia stem pain and another patient with secondary instability. In both cases implant fixation was not the problem, and therefore leaving the well-fixed sleeves in place was considered. Before final decision was made, specific information on implants sizes and constraint are needed. In our tibial revision stem thickness was less than 14 mm decision, in this situation the stem can be removed through the sleeve, leaving the sleeve in place. The technique how to do it, is shown in this study. In the second case a traumatic MCL rupture was leading to a secondary instability, needing a revision from a VVC constraint to a rotating hinge. Again, pre-Op analysis and the surgical technique of femoral component removal are described. In the great majority of cases a full revision with complete implant removal is required. In a few cases a partial revision with maintenance of implant parts can be considered but only after careful analysis of the failure mode. Even if the failure mode allows a partial revision specific implant information need to be obtained to clarify whether it is really possible. If it is possible, a specific surgical technique is recommended and described in this study.