CHAPTER SYNOPSIS

Common complications of shoulder arthroplasty include infection, instability, stiffness, rotator cuff problems, loosening, periprosthetic fractures, and neurologic injury. We discuss the incidence and possible causes and outline methods for diagnosis and treatment. Symptom relief and some functional improvement could be achieved after careful consideration and treatment of these complex and difficult problems.

IMPORTANT POINTS

• 1
  

  The majority of infections occur early and can be treated successfully, although deep infections require staged revisions.

  
  
• 2
  

  Instability and stiffness are mainly related to component malposition, which requires correction by revision surgery.

  
  
• 3
  

  Rotator cuff–related problems are particularly difficult to treat in rheumatoid patients.

  
  
• 4
  

  Periprosthetic fractures are most likely to occur perioperatively; later occurrences are usually due to a fall.

CLINICAL/SURGICAL PEARLS

• 1
  

  Clinical evaluation and positive cultures from intraoperative tissues are considered the gold standards for diagnosing infections in patients with prosthetic joint arthroplasties.

  
  
• 2
  

  There is often more than one cause for instability, and each cause should be addressed in sequence with correction of component positions and reconstruction of soft tissue envelope, followed by appropriate rehabilitation.

  
  
• 3
  

  Component position should be checked and revised if needed. Manipulation should be avoided. Arthroscopic capsular release is an option in resistant cases in which rehabilitation has failed, though arthroscopy in the presence of an arthroplasty is difficult.

  
  
• 4
  

  Once a tear has been identified, it is essential to treat the tear before atrophy and retraction occurs. The method of repair is dictated by the condition of the cuff. Tendon-to-tendon repair, tendon-to-bone repair using bone anchors, or reattachment of a tuberosity may be necessary.

  
  
• 5
  

  Type C fractures can be treated like any other humeral shaft fracture, and most of them heal with nonoperative treatment, although open reduction and internal fixation may be required if the fracture is unstable.

CLINICAL/SURGICAL PITFALLS

• 1
  

  In the authors’ experience, infection mostly occurs in patients who have had previous surgery, especially percutaneous K-wire fixation of a proximal humerus fracture.

  
  
• 2
  

  There is often more than one cause for instability, and each cause should be addressed in sequence.

  
  
• 3
  

  Component oversizing (overstuffing the joint) is also an important reason for stiffness after replacement and should be avoided.

  
  
• 4
  

  It is essential that even during the primary procedure care is taken to preserve and restore cuff musculature as much as possible. It is usually possible in patients with osteoarthritis, but in rheumatoid patients the condition of the cuff can be less than optimal.

  
  
• 5
  

  Excessive torque and reaming during the primary operation, osteoporotic bone, and rheumatoid arthritis are some of the predisposing causes of fractures.

VIDEO AVAILABLE

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INFECTION

Deep infection in shoulder arthroplasty have been reported as being between 0% and 3.9% for unconstrained shoulder arthroplasties and 0% and 15.4% for constrained arthroplasties. Infection occurs more frequently in immunocompromised patients, diabetics, patients on steroids, rheumatoid patients, and patients who have had previous surgery to the shoulder.

Deep joint infection can be classified into acute, subacute, and late. Infection is considered acute if it occurs within 3 months after primary procedure, subacute if it is present between 3 months and 1 year, and late if it appears more than 1 year after the primary procedure.

Redness, swelling, discharge, sinus formation, fever, rigors, and pain are the most common signs and symptoms. Radiographs can show periosteal reaction and radiolucency at the bone–cement or bone–prostheses interfaces, indicating loosening due to infection. In knee arthroplasty patients, erythrocyte sedimentation rate and C-reactive protein have been shown to provide excellent diagnostic information for establishing the presence or absence of infection. In the authors’ experience these tests have poor reliability.

The entire profile of the patient and test results should be considered to make a diagnosis of deep infection, especially in patients who do not have all the classic clinical, radiologic, and hematologic findings. Nuclear imaging such as a LeukoScan may be helpful in indicating a possible diagnosis of infection. In a meta-analysis of the studies on the use of 99mTc-sulesomab (LeukoScan) in infected hip and knee arthroplasty, a sensitivity and specificity of 83% and 80%, respectively, was found, compared with 54% and 83% for the three-phase bone scan.

Clinical evaluation and positive cultures from intraoperative tissues are considered the gold standards for diagnosing infections in patients with prosthetic joint arthroplasties. The most commonly reported infecting organisms after shoulder arthroplasty are Staphylococcus aureus, coagulase-negative Staphylococcus, Propionibacterium acnes, and Strepto-coccus .

Superficial infection during the early postoperative period is treated with appropriate antibiotics. Antibiotic choice depends on cultures from swabs if discharge is present or blood cultures if the patient is pyrexial.

Early deep infections within the first 6 weeks after the primary procedure can be treated by surgical debridement with retention of prostheses followed by intravenous antibiotics administered according to established sensitivities from cultures of tissues obtained during surgery. However, prosthetic removal and revision surgery (one- or two-stage) may be required. Ince et al. (nine patients) and Coste et al. (three patients) have reported good outcomes after single-stage revisions.

Late deep infection is usually due to dissemination from a distant foci. The options available are single-stage revision, two-stage revision, resection arthroplasty, shoulder arthrodesis, and ultimately amputation.

The authors’ experience of shoulder prosthesis infection is that the majority are early and can be treated by revision surgery. Of these patients, infection mostly occurred in patients who had previous surgery, especially percutaneous K-wire fixation of a proximal humerus fracture. One patient presenting late was treated by excision arthroplasty. Two-stage revisions are by far the best option in the authors’ experience, and good results have been reported compared with other treatments. At the first-stage components are removed, a thorough debridement is performed and tissues are obtained for culture and histology. An antibiotic spacer inserted at this stage may help in eradication of infection. Appropriate intravenous antibiotics should be given for at least 6 weeks. The second stage involves further debridement and implantation of new components. Cultures are also obtained at this stage to ensure eradication and to establish the need for further antibiotics. Antibiotic therapy sometimes can be prolonged and is usually tailored to the individual patient. Advice should always be taken from the microbiologists in the institution to avoid inappropriate and indiscriminate use of antibiotics.

Resection arthroplasty is an option in carefully selected patients with deep infection of the shoulder. This should be considered only in patients who have poor general condition and poor soft tissue envelope. Although infection is eradicated, the functional outcome is very poor after this procedure.

INSTABILITY

Subluxation or dislocation after shoulder arthroplasty can occur in all four directions, anterior, posterior, superior or inferior. Causes include malposition of the components, incorrect version of the glenoid or humeral cuts, soft tissue contractures or laxity, and cuff deficiency. Incidence varies from 0% to 38%.

Moeckel et al. showed that all seven anterior dislocations in 236 replacements were due to rupture of subscapularis, whereas the posterior instabilities were due to multiple factors. The predominant factor causing posterior instability is glenoid component malposition in retroversion. This is due secondarily to the posterior glenoid bone loss, which is common in osteoarthritis of the shoulder. Failure to recognize and address glenoid deficiencies during the primary surgery is a surgical error.

Nyffler et al. have also shown that glenoid version plays an important role in both anterior and posterior instability, which leads to eventual loosening of the glenoid component. Altering the humeral anteversion to accommodate the excessive glenoid retroversion does not seem to help in cadaveric studies, although a larger glenoid component provides more stability compared with a smaller one.

Humeral head offset in relation to the axis of the humeral stem has also been shown to affect the amount of anteroposterior translation and superior subacromial impingement. Cadaveric experiments by Williams et al. have shown that variations to the anterior to posterior humeral head offset and superior to inferior offset made a statistically significant difference to the total anteroposterior translation ( p = 0.01) and the total superoinferior translation ( p = 0.03), respectively.

Inferior malposition of humeral components greater than 4 mm can lead to increased subacromial contact. Therefore, if subacromial contact is to be minimized and glenohumeral motion maximized after shoulder replacement, anatomic reconstruction of the humeral head–humeral shaft offset to within 4 mm is desirable.

A thorough imaging evaluation including subtraction technique computed tomography (CT) and magnetic resonance imaging (MRI), as well as appropriate plain radiographs, is essential prior to treating instability. Particular attention must be paid to the position of both humeral and glenoid components with regards to size, version, and offset. Bone deficiencies should be accounted for, and the status of the cuff and the biceps tendon should be established.

There is often more than one cause for instability, and each cause should be addressed in sequence with correction of component positions and reconstruction of the soft tissue envelope followed by appropriate rehabilitation. The surgeon should be aware of the various possible causes for instability and endeavor to correct them even at primary surgery.

Glenoid deficiencies should be corrected with a bone block or metal augmentation, and sometimes both, prior to reimplantation of the component. Modular components for the humerus are quite versatile and allow the surgeon to achieve a desirable construct.

STIFFNESS

Stiffness is a very common problem after any shoulder procedure. Although rehabilitation is important in regaining movement, other factors can contribute to stiffness. Williams et al. have shown statistically significant reduction in range of movements with changes in humeral head offset. Offset of 8 mm in any direction results in significant decreases in passive range of motion. Both anterior-to-posterior and superior-to-inferior humeral head offset were associated with statistically significant changes in total range of motion.

Component oversizing (overstuffing the joint) is also an important reason for stiffness after replacement and should be avoided. Component position should be checked and revised if needed. Manipulation should be avoided. Arthroscopic capsular release is an option in resistant cases in which rehabilitation has failed, though arthroscopy in the presence of an arthroplasty is difficult.