Interventional procedure overview of supercapsular percutaneously assisted total hip arthroplasty for osteoarthritis

Dislocation or subluxation

Dislocation was reported in 1 patient who had THA using the SuperPath approach at 1-week follow up and 2 patients who had THA using the conventional posterior approach at 2-week follow up in the randomised controlled trial of 92 patients (Xie 2017).

Subluxation was reported in 2 patients in the case series of 150 patients and for both patients, there was no complete dislocation because the head was captured by the closed capsule. For 1 patient, subluxation happened 3 weeks after the surgery during elevated sitting and this event related to the surgical technique. The patient had a closed reduction and was doing fine at 1 year after the surgery. For the other patient, subluxation happened in the operating room after turning the patient onto the back. This needed immediate exchange of the head to a longer one. The patient walked without crutches after a few days and had no complaints (Qultmann 2019).

Fracture

Intraoperative femoral calcar fracture was reported in 1 patient in each group in the non-randomised comparative study of 99 patients who had THA using either SuperPath or PATH technique. For the patient in the SuperPath group, the femoral calcar fracture was treated with extension of the skin incision, piriformis release and cerclage wiring. For the patient in the PATH group, the fracture of the femoral calcar was treated with extension of the skin incision and cerclage wiring. For both patients, postoperative weight bearing was permitted without incident (Rasuli 2015).

Intraoperative acetabular fracture was reported in 1 patient who had THA using the SuperPath approach in the non-randomised comparative study of 90 patients. The patient who had teriparatide for osteoporosis experienced this event while the cup component was being impacted. The external rotators were removed and the approach was converted to a conventional posterior approach. Given that osseous acetabular circumferential stability existed, a cemented stem was implanted. At 12-month follow up, evolution was satisfactory, with an HHS score of 82 and a Merle d'Aubigné hip score of 10 (Mas Martinez 2019).

Femoral diaphyseal fracture was reported in 1 patient at 4 weeks postoperation in the case series of 150 patients. The patient was retransferred from the rehabilitation clinic and needed cerclage wiring of the femur and exchange of the stem (Qultmann 2019).

Implant revision

Profemur L Modular Stem: revision was reported in 5% (210/4,233) of primary THA procedures in which Profemur L Modular Stem was used in a NJR implant study of 433,020 patients with osteoarthritis, rheumatoid arthritis, avascular necrosis, fractured neck of femur, CDH/DDH or other indications. When comparing with the number of expected revisions for procedures in which all NJR cementless stems were used, adjusted for age, gender, indications and implantation year, the number of actual revisions for procedures using Profemur L Modular Stem (all bearing types) was statistically significantly higher (210 actual revision compared with 176.14 expected revisions, p=0.012). Analysis of the reasons for revision showed statistically significant differences in implant fracture stem (13 actual revisions compared with 2.58 expected revisions, p<0.001), dislocation or subluxation (38 actual revisions compared with 23.99 expected revisions, p=0.007), infection (37 actual revisions compared with 21.60 expected revisions, p=0.002) and malalignment stem (11 actual revisions compared with 5.05 expected revisions, p=0.02; NJR 2020b).

Procotyl L Cup: revision was described in 3% (187/6,568) of primary THA procedures in which Procotyl L Cup was used in a NJR implant study of 683,939 patients with osteoarthritis, rheumatoid arthritis, avascular necrosis, fractured neck of femur, CDH/DDH or other indications. There was no statistically significant difference between the number of actual revisions for procedures using Procotyl L cup (all bearing types) and the number of expected revisions for procedures using all NJR cementless cups, adjusted for age, gender, indications and implantation year (187 actual revisions compared with 179.45 expected revisions, p=0.574). When considering the reasons for revision, statistically significant differences were reported in adverse soft tissue reaction (11 actual revisions compared with 25.05 expected revisions, p=0.003), infection (38 actual revisions compared with 27.02 expected revisions, p=0.042) and implant fracture stem (19 actual revisions compared with 3.27 expected revisions, p<0.001; NJR 2020c).

Profemur L Classic Stem: revision was reported in more than 1% (11/829) of primary THA procedure in which Profemur L Classic Stem was used in a NJR implant study of 432,625 patients with osteoarthritis, rheumatoid arthritis, avascular necrosis, fractured neck of femur, CDH/DDH or other indications. The difference was not statistically significant between the number of actual revisions for procedures using Profemur L Classic Stem and the number of expected revisions for procedures using all NJR cementless stems, adjusted for age, gender, indications and implantation year (11 actual revisions compared with 8.56 expected revisions, p=0.388; NJR 2020a).

Other complications

Anecdotal and theoretical adverse events

In addition to safety outcomes reported in the literature, professional experts are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never happened).

For this procedure, professional experts listed the following anecdotal adverse events: acetabular reamer breakage and calcar fracture. They considered that the following were theoretical adverse events: intraoperative fracture, postoperative subsidence of implants and other adverse events that are similar to standard hip replacement.