Fitmore Versus CLS Stem in Total Hip Arthroplasty. Bilateral One-stage Operations

Randomized Comparison Between the Fitmore and the CLS Stem in Patients Operated in One-stage Due to Bilateral Symptomatous Hip Disease

Main question: Will use of a stem design that allows anatomical reconstruction of the hip joint improve the outcome in terms of hip function and patient satisfaction without causing any adverse effects?

Background: Total hip arthroplasty with use of the most well documented implants is a safe and cost-effective procedure. In the Swedish Hip Arthroplasty register the CLS stem has a 16 years implant survival of 97, 5 %. It is a classic design which requires resection of most of the neck. The stem also intrudes into the greater trochanter which in patients with certain types of proximal hip anatomy makes proper introduction of the stem difficult. Finally it has a standard stem length which will jeopardise future stem removal should there occur any late infection or instability problems.

Short uncemented stems have been introduced to enable a more anatomic reconstruction of the hip joint and to cause less invasion of the femoral canal to facilitate future revision should it be necessary. A more conservative resection of neck could also be of value to improve the clinical outcome by improved hip function and patient satisfaction.

Purpose of the present study and design: In a prospective study the clinical outcome, stem fixation and bone remodelling around a short stem (Fitmore) will be studied. The main focus will be to evaluate patient reported outcomes especially concerning function, over all satisfaction, pain and activity. All patients will receive the same cup (Trilogy). This cup is chosen because it has a very thorough documentation in prospective RSA studies and in the Swedish hip arthroplasty register. All cups will be supplied with insert made of high molecular polyethylene (Longevity).

Number of hips in the study: 44 consecutive cases

Study Overview

• Status: Active, not recruiting
• Conditions: Surgical Treatment; Primary Hip Osteoarthritis; Secondary Hip Osteoarthritis Due to Idiopathic Femoral Head Necrosis, Childhood or Inflammatory Disease; Bilateral Hip Disease
• Intervention / Treatment: Device: Total hip arthroplasty (Fitmore or CLS uncemented femoral stem made by Zimmer-Biomet, Warshaw, USA)

Detailed Description

Main question: Will use of a stem design that allows anatomical reconstruction of the hip joint improve the outcome in terms of hip function and patient satisfaction without causing any adverse effects?

Background: Total hip arthroplasty with use of the most well documented implants is a safe and cost-effective procedure. In the Swedish Hip Arthroplasty register the CLS stem has a 16 years implant survival of 97, 5 %. It is a classic design which requires resection of most of the neck. The stem also intrudes into the greater trochanter which in patients with certain types of proximal hip anatomy makes proper introduction of the stem difficult. Finally it has a standard stem length which will jeopardise future stem removal should there occur any late infection or instability problems.

Short uncemented stems have been introduced to enable a more anatomic reconstruction of the hip joint and to cause less invasion of the femoral canal to facilitate future revision should it be necessary. A more conservative resection of neck could also be of value to improve the clinical outcome by improved hip function and patient satisfaction.

Purpose of the present study and design: In a prospective study the clinical outcome, stem fixation and bone remodelling around a short stem (Fitmore) will be studied. The main focus will be to evaluate patient reported outcomes especially concerning function, over all satisfaction, pain and activity. All patients will receive the same cup (Trilogy). This cup is chosen because it has a very thorough documentation in prospective RSA studies and in the Swedish hip arthroplasty register. All cups will be supplied with insert made of high molecular polyethylene (Longevity).

Number of hips in the study: 44 consecutive cases

Methods: EQ-5D including VAS-scale to evaluate pain and over all satisfaction, (specific questionnaire concerning side preference), Harris Hip Score, DXA, radiostereometry and gait analysis.

A. Clinical parameters: EQ-5D form (including VAS for pain and satisfaction) is filled in by the patients. Harris Hip Score is filled in by the examiner. SF-36 and activity scale (UCLA) is filled in by the patient. Patients also fill in a study specific form including questions about hip preferred and a pain drawing. Clinical parameters will be studied preoperative after 1, 2, 5, 7 and 10 years.

B. Conventional radiography: Examinations will be done preoperatively, postoperatively, after 1, 2, 5, 7 and 10 years.

C. Computed tomography: Preoperatively, after 1 and 7 years.

D. DXA measurements: Postoperatively, after 6 months, 1, 2, 5, 7 and 10 years.

E. Radiostereometry: Postoperatively, after 3 and 6 months, 1, 2, 5, 7 and 10 years.

F. Gait analysis: 1 and 2 years.

Focus of interest:

A. Patient reported outcomes and especially Oxford Hip Score will constitute our primary outcome parameter.

B. Conventional radiography (preop with metallic indicator to determine magnification) will include AP, True lateral and pelvic view.

C. Computed Tomography will be done for preoperative planning in 3D (a new software has been developed). Preoperative planning in 3D will be done for booth types of prostheses. A prerequisite is that we have 3D-models available for all implants used in the study. Preoperative planning will also be done in 2D.

The CT-examinations will be also used to measure the anteversion of the femur (preoperatively) and of the femoral component (1 year exam). The influence of this parameter on clinical results and fixation will be studied. CT at 7 years will be compared with previous examinations to study development of any osteolysis.

D. DXA - studies will be done to study bone remodelling in terms of changes of bone mineral density around the implant. Both the femoral- and the acetabular side will be studied.

E. Radiostereometry. The cup will be marked during surgery. Model based RSA for the cup Component will also be used. On the femoral side the femoral head centre will be used to measure stem migration. Tantalum markers will be inserted into the acetabular bone and proximal femur.

Femoral component migration will be measured as translations of the femoral head centre in three directions (medial/lateral, proximal/distal, anterior/posterior). Implant migration between the 6 months and 1 year follow up will constitute our second outcome parameter.

Comments: From previous studies of uncemented stems it has been found that these implants often subside up to 1-2 mm and some even more during 6 months (rarely up to 1 year) and may thereafter become stable and at least according to conventional radiography achieve osseous fixation.

Two years after the operation patients will also be studied using dynamic RSA during active abduction and flexion. The aim is to study any-lift off during these motions. A new radiostereometric laboratory has been installed in 2010 which has facilitated these types of examinations.

In addition the fixation of the cup and wear (femoral head penetration) will be measured.

F. Gait analysis will be performed one and two years after the operation. The patients will be studied walking and when rising from a chair. This analysis will focus on flexion/extension, motions of the hip and the knee and the ground reacting forces. The ab/adduction movements over the hip during walking will also be recorded.

• Study Type: Interventional
• Enrollment (Actual): 44
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 35 years to 75 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

1. Hip anatomy suitable for the Fitmore stem according to preoperative planning
2. Males and females aged 35 to 75 years (with bilateral hip disease).
3. Primary osteoarthritis.
4. Secondary osteoarthritis due to idiopathic femoral head necrosis, childhood or inflammatory disease. -

Exclusion Criteria:

1. Treatment with Cortisol or known osteoporosis.
2. Low expected activity rate due to other diseases including any generalized joint disease.
3. Anatomy unsuitable for the Fitmore stem.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Preferred hip (the hip arthroplasty preferred by the patient, right or left side)	Study specific protocol in which the patient from a general view tics one of 3 options: left side, right side or no difference). In the term preferred view the patient is asked to consider all aspects they Think are important such as freedom from pain, mobility, function or any other type of discomfort.	2 years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Stem subsidence (distal migration of the stem)	Stem subsidence in mm (distal migration of the femoral head center) measured with radiostereometry	2 years
Extent of radiolucent lines around the stem	Development of radiolucent lines in percent of total stem circumference as measured on conventional radiographs	2 years
Any new surgical procedure where the stem is removed or Exchanges (revision of the stem)	Stem Exchange or removal due to loosening, dislocation or periprostheic fracture	2, 5 and 10 years

Collaborators and Investigators

• Sponsor: Sahlgrenska University Hospital, Sweden
• Collaborators: Zimmer Biomet
• Investigators: Principal Investigator: Johan N Kärrholm, MD, Professor, Sahlgrenska University Hospital, Sweden

Study record dates

Study Major Dates

• Study Start (Actual): March 17, 2011
• Primary Completion (Anticipated): June 1, 2026
• Study Completion (Anticipated): June 1, 2026

Study Registration Dates

• First Submitted: March 7, 2017
• First Submitted That Met QC Criteria: April 7, 2017
• First Posted (Actual): April 13, 2017

Study Record Updates

• Last Update Posted (Actual): April 13, 2017
• Last Update Submitted That Met QC Criteria: April 7, 2017
• Last Verified: April 1, 2017

More Information

Terms related to this study

• Keywords: Arthroplasty; Outcome; Hip; Stem
• Additional Relevant MeSH Terms: Pathologic Processes; Joint Diseases; Musculoskeletal Diseases; Rheumatic Diseases; Arthritis; Osteoarthritis; Necrosis; Osteoarthritis, Hip; Physiological Effects of Drugs; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Enzyme Inhibitors; Gastrointestinal Agents; Cytochrome P-450 Enzyme Inhibitors; Anti-Ulcer Agents; Histamine Antagonists; Histamine Agents; Cytochrome P-450 CYP1A2 Inhibitors; Histamine H2 Antagonists; Cimetidine
• Other Study ID Numbers: Fitmore2011

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No