Retrospective analysis of outcomes and complications after Korus hemiarthroplasty in elderly patients with neck femur fractures.

BACKGROUND: Femoral neck fractures (FNF) is one of the most common traumatic events in elderly patients: the choice of an appropriate treatment is necessary to decrease the related mortality and to achieve the best possible outcomes. Nowadays, it is still debated whether or not to cement the stem in hemiarthroplasty and above all, which stem to use to best respect the integrity of the elderly bone.
METHODS: From January 2017 to December 2019, a bi-centric study utilizing prospectively collected databases of elderly patients with FNF treated with uncemented Korus stem hemiarthroplasty was performed. Patients were preoperatively classified according to ASA score. Patients' clinical and X-ray follow-up was at 1, 3, 6, 12 months. Harris Hip Score (HHS) was used for analysed clinical improvement. On the X-rays, we analysed iatrogenic fractures, osteolysis area and radiolucent lines in the stem region during follow up.
RESULTS: 233 patients were identified. Median follow-up was 12 months. Over time, 51 patients died (21.88%). Mean age was 89,56 ± 6,25. 75 patients had ASA score of 2 (32.3%), 102 patients a score of 3 (43.7%), 56 an ASA score of 4 (24,0%). The main Harris hip score was 68,66 ± 8.53 at 1 month of follow-up, 71,74 ± 9.65 after 3 months, 72,50 ± 10.66 at 6 months and 75,61 ± 9.63 at 12 months control.
CONCLUSIONS: Hydroxyapatite coated stem with an accurate design guarantee early fixation, good clinical and radiographic results, low rate of re-intervention and mortality rate and a satisfying return to pre-injury activities.

Introduction

Femur fracture is a traumatic event the Orthopaedic Surgeon daily deals with. In recent years, the progressive aging of the population has inevitably increased these types of traumas. After hip fracture, elderly people’s quality life is often compromised and, in any case, it presents lower standard of living compared to non-fractured people of same age and gender (1). Furthermore, 30% of patients d die during the first year after trauma (2), showing percentages up to 50% at 5 years (3).

According to the accuracy of surgical techniques and the introduction of new implants, aims of orthopedic surgeons changed: if in the past it was fundamental to obtain a durable and free from complications implant over time as well as from pain, recently the restoration of normal joint function, normal muscle function and correct leg length were added to the main purposes of the procedure (4).

Lately, new design and materials have been developed to obtain more anatomical and functional implants (5).

Data suggests that implant longevity and mortality rate are both influenced by: primary press-fit stability, type of fixation and coating and morphological aspects of the components (6-8).

In our study we analyze clinical and radiographic outcomes of patients treated for intracapsular neck fractures using uncemented hemiarthroplasty with collarless stem andHydroxyapatite coating.

Materials and Methods

In this three-Centers study, we analyze a group of 233 elderly patients treated for FNF with uncemented hemiarthroplasty (UCH) from January 2017 to December 2019 in Guglielmo da Saliceto Hospital, Piacenza, Italy, Santa Maria delle Croci, Hospital Ravenna, Italy and S.S. Annunziata, Hospital, Savigliano, Cuneo, Italy.

All surgical procedures were performed by the respective Heads of Prosthetic Surgery of the three Departments, leading experts in both total and partial hip arthroplasty (9). In 138 patients “Hardinge lateral approach” was used, with subject placed in supine position(10); instead the other 95 patients were operated using postero-lateral approach. A non-cemented collarless stem, with hydroxyapatite coating and 135° or 125° CCD angles (Korus®, Bioimpianti, Milan, Italy) was implanted in every patient (Figure 1).

Figure 1.

Korus® hemiarthroplasty, with non-cemented collarless stem and hydroxyapatite coating.

We always applied subfascial surgical drain. After 48 hours the drain was removed and the patient began the rehabilitation process, maintaining the sitting position on the first day and on the following day starting with a walker-supported walking.

After surgery, X-ray of hip and pelvis was obtained. Patients’ clinical and X-ray follow-up was at 1, 3, 6, 12 months and then for any complications or clinical problems. Radiographic evaluation was performed according Vresilovic criteria (11). Standard views were performed (antero-posterior and axial) in X-ray control. In particular, we analyzed iatrogenic fractures, osteolysis area and radiolucent lines in the stem region. Stem correct fitting, calcar resorption and heterotopic ossification were also assessed. For the clinical evaluation we used the Harris Hip Score (HHS), which has a maximum value of 100. A score lower than 70 is considered poor outcome, 70–80 fair, 80–90 is good, and 90–100 is an excellent outcome.

Results

The cohort was composed by 233 patients, 149 females (63,9%) and 84 males (36,1%). Average age was 89,56 years ± 6,25. Patients were classified in 5 groups according to the anaesthetic risk evaluation by using the ASA score (12). 75 patients had an ASA score of 2 (32,3%), 102 a score of 3 (43,7%), 56 a score of 4 (24,0%).

During the follow-up period 51 patients died (21,88%). Of these, 7 presented ASA 2 score (13.7% of dead, 9.3% of total ASA 2 patients); 23 presented ASA 3 score (45.1% of dead, 22.5% of total ASA 3 patients); 21 presented ASA 4 score (41.2% of dead, 37.5% of total ASA 4 patients);

The mean Harris Hip Score was 68,66 ± 8.53 at 1 month follow-up, 71,74 ± 9.65 after 3 months, 72,50 ± 10.66 at 6 months and 75,61 ± 9.63 at 12 months.

6 case of infections were reported (2,57%). 2 of them were treated with surgical washout and substitution of polyethylene components, 3 of them were treated with implant removal, antibiotic therapy and revision implant at infection-index normalization. The last one was treated with Gilderston procedure.

7 patients had prosthesis dislocation (3%), while 7 (3%) showed Trendelemburg limp.

We register 2 cases of periprosthetic fractures (1 A and 1 B1 according to Vancuver classification) treated with cerclage wire or plate and screws (Figure 2).

Figure 2.

Periprosthetic fracture (A according to Vancouver classification) treated with cerclage wire.

We noticed calcar resorption in 3 patients’ X-ray controls (2,17%). A valgus stem alignment was found in 4 patients (2.89 %).

Discussion

Femur fracture in elderly people presents high risk of mortality at one-year follow-up. In a study conducted by Eiskjaer (13) the mortality rate after six months was 20% reaching value of 28% at 1 year follow-up. Many factors such as cardio-pulmonary comorbidities, serum creatinine level > 1.7 mg/100 ml, duration of surgery and gender influence the survival rate of these patients. Kastanis showed how the ASA classification system is correlated with multiple factors, which can lead to the prediction of the postoperative status, and our data get along with this theory confirming that patients with higher ASA scores present an increased risk of mortality. In fact, 37.5% of ASA 4 patients died during follow-up, higher compared to patients with lower ASA score (mortality rate of 9.3% for ASA 2, 22.5% for ASA 3)(12).

The influence of fixation type in survival rate is very discussed in literature. Rivera underlines a higher mortality rate in patients treated with a cemented stem (6). Several possible complications are cited to explain this phenomenon: embolization of fat, bone marrow, and cement particles. Costan (14) shows that patients treated with cemented monoblock hemiarthroplasty had a 1.7 times higher day-1 mortality compared to uncemented monoblock components but higher mortality 1 week, 1 month, and 1 year after surgery.

For these reasons we decided to use an uncemented stem, with hydroxyapatite coating, tapered geometry for increased ROM, decreased risk of impingement and low trochanteric invasivity (Korus®, Bioimpianti).

The hydroxyapatite-coating (HA) could be an important factor for bone remodeling around the stem and for the subsequential early stabilization of the implant. According to Dorr, hydroxyapatite-stems have better stability, good clinical and radiographic results (10-15). The stems stabilized in 3 months due to the bioconductive capability of HA which provides earlier stability of the stem with more bone attachment. This type of stem had less risk of subsidence or migration than cemented stems. Other studies confirmed the higher degree and quality of osteointegration in the porous titanium alloy/HA type implants (16).

HA coating loss could be a long-term adverse event of HA coating- stems. According to Rivera, HA coating loss could have different causes: osteoclastic remodeling, delamination, chemical dissolution. It was demonstrated how in load area around the implant, osteolysis is followed by lamellar bone deposition that replace the coating and guarantees a long term osteointegration (6).

Geesink showed that there is no evidence of osteolysis associated with HA particles. Furthermore, the study confirmed early pain relief and durable fixation of the stem, with an excellent periprosthetic bone quality and an increased bone mass (7).

Molli showed a higher rate of intraoperative complications with length-stems compared to shorter ones (8). In our experience we didn’t register any case of intraoperative fractures: this could be explained by the lower trochanteric invasivity of Korus stems, which allows easier insertion and smaller incisions, leading to a lower risk of iatrogenic fractures.

Smaller incision lead in less risk of medium gluteus damaging, with a lower rate of limp and pain after surgery.

Our results showed a good return to daily activities for the majority of patients with only 7 cases of Trendelemburg limp.

Conclusions

Hydroxyapatite coated stem with less invasive design guarantee early fixation, good clinical / radiographical results and low rate of re-intervention.