Functional and radiological outcome of uncemented total hip arthroplasty in young adults - 5 year follow-upollow-up

Abstract

Background

End stage arthritis in young patients requires surgical intervention. THA remains the treatment of choice for restoring function and activity in end stage hip arthritis. The medium term outcome of uncemented THA in Indian population is less studied. Hence this study was taken up with aim to study clinical and radiological outcome of uncemented THA in patients with age less than 40 years.

Methods

This study was conducted during January 2013 to December 2013. Overall 66 patients with 74 arthritic hips were operated by single surgeon (1st Author) with Uncemented THA. All patients were either unilateral or bilateral arthritis of hip less than 40 years of age. Patients were evaluated preoperatively and postoperatively. After discharge patients were followed up at regular intervals. Activity level and Harris Hip score was calculated. Radiological evaluation was done with anteroposterior and lateral X-rays.

Results

Total 50 patients (56 hips) followed up at five year follow-up. Clinical and radiological evaluation was done during follow-up. Most common etiology was avascular necrosis of hip (56.6%). None of the patients had any major complications. Mean Harris Hip score improved from 36 to 92. The activity level was assessed at five year follow-up with maximum patients in moderate manual labor category. Bony ingrowth with no evidence of loosening was seen consistently both on femoral and acetabular side in all patients on X-ray. No statistically significant association was found between initial alignment of the femoral component and clinical outcome

Conclusion

Uncemented THA can be used in young patients with excellent to good functional and radiological outcome at midterm follow-up, high satisfaction rate and lower rate of complications.

1. Introduction

Young adults may suffer from hip arthritis due to various etiological disorders such as Ankylosing spondylitis, post-traumatic arthritis or avascular necrosis of femoral head. It leads to disability severely compromising activities of daily living in these young patients. End stage arthritis in such patients requires surgical intervention. Earlier days, hip arthrodesis or resection arthroplasty were the preferred options but since last couple of decades total hip arthroplasty has emerged as successful option with good functional results.¹ With the advances in design and materials used for implants the success rate has increased in even high demand patients. Thus, THA remains the treatment of choice for restoring function and activity in end stage hip arthritis.¹ Although THA was earlier considered only for elderly patients, good functional results have been reported by multiple studies in younger patients.^2,3

Although there is reported decreased survivorship of uncemented THA components in young patients due to high demand patients, repetitive cyclic loading and high activity level, the advances in design and bearing surfaces has led to increasing number of THA in young patients. The medium term outcome of uncemented THA in Indian population is less studied. Hence this study was taken up with aim to study clinical and radiological outcome of uncemented THA in patients with age less than 40 years.

2. Materials and methods

This longitudinal study was conducted during January 2013 to December 2013 in an Orthopedic department of a tertiary care center of metropolitan city of India. Overall 66 patients with 74 arthritic hips were operated by single surgeon (1st Author) with Uncemented THA. All patients with either unilateral or bilateral arthritis of hip less than 40 years of age were included in the study. Patients with dysplastic hips, history of septic or tubercular arthritis or neurological weakness of limb were excluded from the study. Femoral component (POLARSTEM ™) (Fig. 1), acetabular component (R3 acetabular cup), highly cross-linked polyethylene liner (XLPE ™) and metal head (Oxinium ™) (Fig. 2) was used for all hips in this study. The stem used is non-collared, double tapered, titanium stem with plasma Hydroxyapatite coating. All surgeries were performed through standard posterolateral approach in lateral decubitus position under regional or general anesthesia. Antibiotics were given 20 min preoperatively and continued postoperatively till 48 h. DVT prophylaxis was given only in selected patients. Mobilization was started from 1st postoperative day full weight bearing with walker.

Fig. 1.

Uncemented fully HA coated double tapered femoral stem (POLAR STEM™).

Fig. 2.

Porous coated Hemi-spherical uncemented cup (R3™), highly cross-linked polyethylene liner (XLPE™) and zirconium metal head (Oxinium ™).

Patients were evaluated preoperatively and postoperatively. After discharge patients were followed up at three months, six months and yearly thereafter. For functional evaluation multiple factors were taken into consideration. Activity level used in study is defined by Johnston et al.⁴ as follows heavy manual labor defined as lifting 23–45 kg or engaged in vigorous sports, moderate manual labor defined as lifting 23 kg or less and involved in moderate sports, light labor included heavy lifting, house cleaning, and walking less than five km. Semi-sedentary indicated white collar job or light housekeeping. Sedentary activity indicated minimal capacity for walking, and bedridden was defined as being confined to a wheelchair or bed. Harris Hip score was used to evaluate the functional outcome at five years follow-up.⁵

Radiological evaluation was done with anteroposterior and lateral X-rays. The immediate postoperative X-rays were compared with the 5year follow-up X-rays. On X-rays, Gruen zones were identified and radiolucencies were searched.⁶ Radiolucencies with a scalloped or cystic appearance or greater than two mm in width were recorded as osteolysis.

Subsidence was evaluated by measuring the distance the stem has settled. If the stem settled more than four mm it was considered as subsidence.⁷ Femoral component alignment was evaluated. It was considered neutral if the line passing through center of implant and the femur were within three degree. A difference of greater than three degree indicated a varus or valgus orientation.⁸ Statistical analysis was done using SPSS 21.0 version and Student t-test and Fisher exact test were used to determine significance.

3. Results

During the study, total 50 patients (56 hips) followed up at five year follow-up. Clinical and radiological evaluation was done during follow-up. Mean age of patients at the time of surgery was 27.5 years (range 21–38 years). Out of 50 patients, 34 were male and 16 were female. Most common etiology was avascular necrosis of hip (56.6%) followed by posttraumatic (20.8%), Ankylosing spondylitis (15.9%) and Rheumatoid arthritis (6.7%). Mean operative time was 75 min (range 60–90min), mean period of hospital stay was 14 days (range 12–16 days) and mean blood loss 300 ml (range 250 ml–450 ml). Five patients (10%) complained of anterior thigh pain which subsided over period of three months with conservative treatment. Three patients had superficial wound complications which were managed with secondary suturing. Three patients had limb lengthening more than 2 cm. One patient has intraoperative calcar fracture which we managed with cerclage wiring and weight bearing was delayed for three weeks. None of the patients had any major complications. Mean Harris Hip score improved from 36 (preoperative) to 92 (five years follow-up) which is suggestive of marked improvement in the functional outcome (Table 1).The activity level was assessed at five year follow-up with maximum patients in moderate manual labor category (Table 2). Bony ingrowth was seen consistently both on femoral and acetabular side in all patients on X-ray (Fig. 3). No femoral or acetabular component loosening was seen on X-rays. Three patients had shown subsidence of two mm during 3 month follow-up, but they remained stable at five year follow-up. On radiological assessment for alignment of femoral stem, we found that 46 (82.14%) hips were in neutral position, eight (14.28%) hips were in valgus and two (3.57%) were in varus. Angle of inclination for acetabular component was between 40 and 50° in 95% of patients. The mean acetabular inclination was 44.2° (range 38–53). No statistically significant association was found between initial alignment of the femoral component and clinical outcome.

Table 1.

Harris hip scores of patients showing functional outcomes

Results of Harris hip Score	Excellent	Good	Fair	Poor
Number of hips	32	21	3	0
Percentage	57.14%	37.5%	5.35%	0

Table 2.

Activity level of patients in study according to Johnston et al.

Results of Activity level	Strenuous manual labor	Moderate manual labor	light labor	Semi sedentary	Sedentary
Number of patients	6	34	4	6	0
Percentage	12%	68%	8%	12%	0

Fig. 3.

Five year follow up X-ray showing good osseointegration of femoral and acetabular component.

4. Discussion

THA has proven itself in elderly patients as a successful procedure with good long term functional outcome.9, 10, 11 Recently, the use of uncemented THA has increased in young adults which may give rise to debate. The literature reporting functional outcome of uncemented THA in young population is less.^2,12 Taking other alternatives of THA such as Hip arthrodesis and Resection arthroplasty in consideration. Both provide pain relief at the cost of restriction in activities of daily living such as inability to sit in chair, difficulty in using public transport. Patients also limp affecting hip biomechanics to such an extent that they may have low back pain and ipsilateral knee pain in medium or long term. Resection hip Arthroplasty leads to worse Harris Hip score, very low satisfaction rate and poor functional outcome. Also the gait provided by both these options has very high energy consumption (260% higher than normal)^13,14 Also both these options cannot be done in bilateral involvement. Moreover, the most common diagnosis for THA in our study is avascular necrosis of hip which is known to be bilateral in 30–40% patients.^15,16

Few studies have reported higher failure rate of THA in young patients and have attributed it to higher physical activities.¹ There are various improvements in uncemented implant's design, materials, bearing surfaces and surgical care leading to improved survival of implants. Thus, they have become the implant of choice over cemented THA for management in young adults.

As in our study, uncemented THA has reported excellent to good functional outcome and excellent radiological outcome. We are of the opinion that fully HA coated titanium femoral components and porous coated uncemented cup with highly crosslinked polyethylene liner can provide durable biological fixation in young patients.

There are certain limitations of this study such as, the cohort of patients has different number of diagnoses which may affect outcome and act as confounding factor. Five year follow-up is a relatively short follow-up. Although there are limitations to this study, study is important in the fact that it is prospective study and reports outcome of uncemented THA in young patients.

Source(s) of support

NIL.

Conclusion

Uncemented THA can be used in young patients with excellent to good functional and radiological outcome at midterm follow-up, high satisfaction rate and lower rate of complications. Longer follow-up and multicentric studies with larger sample size are necessary to establish confirmatory results.

Declaration of competing interest

None declared.