Biological characteristics of stemless hip arthroplasty and the recovery of hip joint function in young patients:A follow-up of medium- and short-term outcome

Xinli ZHAN; Zengming XIAO; Shide LI; Qianfen CHEN; Gaobin LUO

ABSTRACT

BACKGROUND:

The standardized treatment for patients who require total hip replacement is the implantation of an intramedullary diaphyseal anchored hip prosthesis. A bone-sparing non-stemmed hip prosthesis (NSHP) can be used as an alternative device for young patients. The NSHP relies on proximal femoral metaphyseal and neck fixation. The theoretic advantage of leaving diaphyseal bone intact is easier conversion to a stemmed prosthesis. On the other hand,clinical investigations published reported THR had high loosening rate of the prosthesis, which greatly limits its long-term clinical results; the aim of NSHP is to give the femoral prothesis a kind of biological fixation to decrease the loosening rate of the prosthesis. This retrospective study evaluated the medium- and short-term results after total joint replacement using NSHP.

OBJECTIVE:

To evaluate the outcome of NSHP for the treatment of young patients with hip disorders.

DESIGN:

Case analysis.

SETTING:

Department of Orthopaedics, the First Affiliated Hospital of Guangxi Medical University.

PARTICIPANTS:

Fifteen patients (17 hips) with hip disorders, who were treated at the Department of Orthopaedics,First Affiliated Hospital of Guangxi Medical University between 2001 and 2005, were retrieved. The involved patients included 8 males and 7 females. They were aged (37.8±9.8) years ranging from 21 to 49 years when they underwent operation. Indications for implantation included avascular necrosis (7 hips), posttraumatic osteoarthritis(4 hips), primary osteoarthritis(3 hips), osteoarthritis secondary to dysplasia(3 hips). Informed consents were obtained from all the patients before operation. The neotype of non-stemmed hip prosthesis (NSHP) was made of Co-Cr-Mo casting alloy with good biocompatibility by Shanghai Fusheng Medical Equipment Co., Ltd (Guoyao guanxie (shi) No. 2002-3040397; Guoshi Yaojianxie(zhun) No. 2005-3460799).

METHODS:

Fifteen patients (17 hips) with hip diseases subjected to the replacement of total hip with NSHP. Patients were followed-up once every other 6 months in the postoperative first year, then once every year, 5 years in total. The follow-up visit included functional evaluation and X-ray evaluation. ① Functional evaluation Evaluative criteria of Harris joint function scale were adopted full marks (point) =100, ≥ 80 excellent, ≥ 60 good, 40 fair and ＜ 40 poor; The following clinical data were documented relief of pain, ability to lie on the operated side, additional procedures, use of pain medication, postoperative hip dislocations and so on. Pain was evaluated by using visual analogue scale (VAS),which ranged from 0 (no pain) to 10 (worst possible pain). ② X-ray evaluation A standardized radiographic assessment was performed using an anteroposterior view of the pelvis. The following radiological data were recorded preoperative grade of osteoarthritis as classified according to the method from Busse et al, preoperative grade of femoral head necrosis as classified according to the method from Ficat et al, inclination angle of the operated and the untreated side,radiolucencies according to the method of Buergi et al, heterotopic ossifications, as classified according to the method of Brooker et al. Postoperative adverse events and complications were observed and revision operation was needed if necessary.MAIN OUTCOME

MEASURES:

Correlative conditions of patients who were followed up for 5 years ① Inserting angle of prothesis and the collodiaphyseal angle in the opposite side. ②Radiolucency and heterotopic ossification classification.③preoperative osteoarthritis classification, preoperative avascular necrosis of femoral head classification. ④ Revision operation, adverse events and complications. ⑤ Postoperative functional evaluation Relief of pain (Harris joint function score), ability to lie on the operated side, additional procedures, use of pain medication, postoperative hip dislocations and VAS results.

RESULTS:

Fifteen patients were involved. One patient was lost after 3-month treatment and the other patients were followed up for 5 years. ① Postoperative functional evaluation results of patients. In the postoperative 5-year follow-up visit, hip joints of 13 patients (15 hips) were still in situ, pain lessened or disappeared in 11 patients (84.6% ,11/13),12 patients(92.3%, 12/13) would undergo the procedure again, 10 patients (76.9%, 10/13) were able to lie on the operated side; The average of Harris hip score was (72±19.6). The average Harris hip score did not vary significantly between the different diagnosis groups (P ＞ 0.05). Postoperative VAS was 2.6±2.2 on average. There was no significant difference in the hip joint pain among different diagnosis groups (P ＞ 0.05); Nine patients required no pain medication (69.2%,9/13).Two patients (15.4% ,2/13) occasionally took nonsteroidal anti-inflammatory drugs and two patients (15.4% ,2/13) took nonsteroidal anti-inflammatory drugs on a regular basis. ② X-ray evaluation results of patients Preoperative osteoarthristis classification One hip had grade 1 joint degeneration, 3 hips had grade 2 joint degeneration and 6 hips had grade 3 degeneration. Preoperative avascular necrosis of femoral head classification Out of 7 patients with avascularnecrosis of femoral head, 4 patients had stage 3 femoral head necrosis, and 3 patients had stage 4 femoral head necrosis. In the postoperative 5-year follow up, 1 patient had radiolucency. Because the range of radiolucency was very small, progression was not quick and clinical symptoms were not severe, so revision operation was not conducted;In the postoperative 6th month, the inclination angle averaged (135.2±6.8)° on the untreated side and (132.2±6.5)° on the treat side. One patient with congenital hip dysplasia and a previous varus derotational osteotomy had a postoperative inclination angle below 120°. Patients with postoperative inclination angles between 125° and 140° had significantly less hip pain than the rest of the series. Heterotopic ossifications classification Three patients had postoperative heterotopic ossifications, one hip had grade 1 heterotopic ossification, 1 hip had grade 2 heterotopic ossification, and 1 hip had grade 3 heterotopic ossification.③ Revision operation one patient (5.9%,1/17)required a revision total hip arthroplasty due to pain. Good bone stock of the proximal femur was found in the patient which allowed implantation of a conventional medullary anchored prosthesis. This revision surgery and postoperative rehabilitation were uncomplicated.④ Adverse events and complications Hip dislocation occurred postoperatively in one patient (5.9%,1/17). Other complications included trochanter bursitis (n=1), fistula (n =1), and seroma (n =1).

CONCLUSION:

① NSHP provides biological fixation for femoral prothesis by bone proliferation through the windows with connective tissues surrounding the prothesis and has the characteristics of low stress and deformation, high intensity and rigidity, and anti-loosening, thus, may prolong its live lime. ②Revision surgeries are facilitated by the good bone stock remaining in the proximal femur. ③ The short- and medium-term therapeutic effects of total hip arthroplasty are satisfying in young patients.