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Journal Club

May 2010

Failure of metal radial head replacement

• Authors: R. P. van Riet, J. Sanchez-Sotelo, B. F. Morrey
  
• Institution: Mayo Clinic, Rochester, Minnesota, United States
• Journal: J Bone Joint Surg [Br] 2010;92-B:661-7, VOL. 92-B, No. 5, MAY 2010
• Study type
  
  • Retrospective case series of joint registry database
    
  • Level IV evidence
  • Non-funded

 

Introduction

• Background
  
  • Replacement arthroplasty of the head of the radius is commonly used in the treatment of radiocapitellar disorders.
    
  • Acute fracture, and chronic conditions, including nonunion, malunion, post-traumatic osteoarthritis, and when symptoms arise following previous resection of the head
    
  • Most reports of replacements are in the short- or medium-term, and there are very few long-term follow-up studies.
    
  • Failure of replacement leading to revision surgery is mentioned in several studies, but the specific mechanisms of failure and the results of reoperation are currently unknown
    
• Aim
  
  • examine the mechanism of failure requiring revision surgery
    
  • document the findings at the time of re-operation

Methodology

• Inclusion
  
  • Revision of radial head replacement at Mayo clinic 1998-2008
• Exclusion
  
  • Patients who had a failed silastic prosthesis
    
  • failure of a radial head component as part of a total elbow or radiocapitellar arthroplasty
• Outcome Parameters
  
  • Timing of initial operation, post-operative complications, mechanisms of failure, and the type of revision surgery.
    
  • The design and fixation used in both the primary and revision procedure.
    
  • Range of movement
    
  • X-Rays
    
    • loosening, instability and radial over-lengthening relative to the lesser sigmoid notch of the ulna.
      
    • joint 'over-stuffing' leading to asymmetry of the ulnohumeral joint.
      
    • Any degenerative changes were graded using the Broberg and Morrey osteoarthritis (OA) scale
      
      • 0 normal elbow
      • 1 mild
      • 2 moderate
      • 3 severe degenerative changes

Results

• Results
  
  • 45 elbows (42 patients)
    
  • 42 fractures
    
    • 32% 1/52,
    • 17% 6/52,
    • 52% >6/52
      
• Initial Radial head replacement
  
  • Initial in 11
    
  • Failure in 34
    
  • ORIF 11, Resection 17, Arthroplasty 6
    
  • Prior revision 7
• Design and fixation
  
  • Initial radial head
    
    • Cement 9
      
    • Uncemented 38
      
    • Uncemented polished 13 stems.
      
    • Bipolar design 8
      
    • 4 in prior revisions.
      
• Reason for Revision
  
  • Clinical reasons for failure of radial head prosthesis
    
    • Pain 40
      
    • Stiffness 18
      
    • Instability 9
      
    • Infection 2
      
• Preoperative ROM
  
  • Mean flexion-extension arc 86° (30° to 150°)
    
    • Mean flexion 117° (60° to 150°)
      
    • Mean FFD 30° (0° to 65°)
      
    • 18 patients (20 elbows) functional ROM >100°,
      
    • at least 130° of flexion to < 30° fixed flexion deformity.
      
  • Pronation-supination arc mean of 110° (0° to 185°),
    
    • Mean pronation of 58° (-15° to 95°)
      
    • Mean supination of 52° (0° to 90°).
      
    • 28 patients (30 elbows) functional arc of rotation
      
      • from at least 50° of pronation and 50° of supination.
        
  • No significant difference for flexion, extension, pronation and supination between designs (p > 0.05).
• Overstuffing - ROM
  
  • No significant difference between overstuffed and correct length prosthesis
    
    • flexion, extension, pronation and supination
      
    • (student t-test; flexion p = 0.38, extension p = 0.45, pronation p = 0.79, supination p = 0.65).
      
• Radiological findings – Pre-revision
  
  • Implant related
    
    • Loosening 31
      
      • 3 cemented, 11 designed to be loose in canal
        
    • Over-lengthening (over-stuffing) 11
      
    • Radial head subluxation 5
      
    • Radial head dislocation 3
      
    • Component dissociation head from stem 3
      
  • Broberg and Morrey osteoarthritis
    
    • Grade 0 - 1
      
    • Grade 1 - 24
      
    • Grade 2- 13
      
    • Grade 3 - 9
• Further procedures
  
  • 18 radial head replacements were removed and not replaced.
    
    • 1 Bipolar stem left in situ
      
  • 24 radial head replacement revised to radial head replacement.
    
    • 18 cemented revision stem
      
    • 17 Bipolar design
      
  • 2 radial head component of a bipolar design was replaced, and the stem was left in situ.
    
    • 1 polyethylene component and a capitellar replacement
    • 1 because of dissociation of this component from the stem.
      
  • 3 total elbow replacements
    
    • These three patients (three elbows) are not included in the data in table IV.
      
• Severe erosion of the articular cartilage of the capitellum was noted at the time of further operation in 20 elbows.
  
• Design and the timing of the Index replacement of the radial head.
  • There was no significant difference in this interval between the loose-stem unipolar and the fixed-stem unipolar, nor between the fixed-stem unipolar and the fixed stem bipolar designs.
    
  • There were no significant differences between designs for time to failure or osteoarthritis scores (p > 0.05).
    
  • Loosening was less common in fixed-stem bipolar implants.
    
    • Five of eight fixed stem bipolar implants had been cemented in place,
      
    • Three were uncemented.
      
  • Radiocapitellar subluxation did not occur in any of the bipolar implants, but capitellar erosion was more prevalent in this group.
• Initial timing of index replacement
  
  • More bipolar prostheses were used in reconstructive procedures delayed more than six weeks after trauma.
    
  • Significant increased osteoarthritis score in Delayed implantation(> 6 weeks) compared with Acute implantation < 1 week (p = 0.03).
    
  • Radial head implanted between 1 to 6 weeks compared to acutely
    
    • Significantly increased fixed-flexion deformity (p = 0.03).
      
    • Over-lengthening
      
    • radial head subluxation
      
    • component dissociation
      
    • Instability all occurred more often
  • Radial head implanted more than six weeks after trauma
    
    • Capitellar erosion more frequent

Discussion

• Conclusions
  
  • Implant loosening
    • most common radiological finding prior to further surgery
    • 29 patients (31 elbows).
      
    • pain
      • In contrast with other authors, all 29 patients (31 elbows) with a radiologically loose implant had pain, which was moderate or severe in 28 patients (29 elbows).
        
    • Loosening of a fixed-stem bipolar implant was less common
      
  • Reduced movement
    • most common indication for further surgery
      
  • Delayed surgery
    • more challenging
      • Radial head replacement at one and six weeks may be technically more challenging.
        
        • significantly reduced extension compared with the acute group (p = 0.03)
          
    • Other technical issues
      • such as over-lengthening, radial head subluxation, component instability, all occurred more frequently.
        
  • Timing
    • most important factor in predicting the prevalence of capitellar erosion
      
    • (55%) who had a radial head replacement inserted more than six weeks after trauma there were clear signs of capitellar erosion.
      
  • Failed radial head replacements may lead to:
    • re-operation for pain,
    • reduced range of movement,
    • instability
    • infection
      
  • Radiological loosening was prevalent in this group of failed replacements.

Pros of Study

• Provides analysis of failed radial head replacements

Cons of Study

• Retrospective
  
• heterogeneous group
  
• wide range of indications for radial head replacement
  
• different designs.
  
• No indication of overall incidence of failure