Subacromial decompression surgery for adults with shoulder pain: a clinical practice guideline

CLINICAL QUESTION

Do adults with atraumatic shoulder pain for more than 3 months diagnosed as subacromial pain syndrome (SAPS), also labelled as rotator cuff disease, benefit from subacromial decompression surgery? This guideline builds on to two recent high quality trials of shoulder surgery.

CURRENT PRACTICE

SAPS is the common diagnosis for shoulder pain with several first line treatment options, including analgesia, exercises, and injections. Surgeons frequently perform arthroscopic subacromial decompression for prolonged symptoms, with guidelines providing conflicting recommendations.

RECOMMENDATION

The guideline panel makes a strong recommendation against surgery.

HOW THIS GUIDELINE WAS CREATED

A guideline panel including patients, clinicians, and methodologists produced this recommendation in adherence with standards for trustworthy guidelines and the GRADE system. The recommendation is based on two linked systematic reviews on (a) the benefits and harms of subacromial decompression surgery and (b) the minimally important differences for patient reported outcome measures. Recommendations are made actionable for clinicians and their patients through visual overviews. These provide the relative and absolute benefits and harms of surgery in multilayered evidence summaries and decision aids available in MAGIC (www.magicapp.org) to support shared decisions and adaptation.

THE EVIDENCE

Surgery did not provide important improvements in pain, function, or quality of life compared with placebo surgery or other options. Frozen shoulder may be more common with surgery.

UNDERSTANDING THE RECOMMENDATION

The panel concluded that almost all informed patients would choose to avoid surgery because there is no benefit but there are harms and it is burdensome. Subacromial decompression surgery should not be offered to patients with SAPS. However, there is substantial uncertainty in what alternative treatment is best.

A covalent succinylcysteine-like intermediate in the enzyme-catalyzed transformation of maleate to fumarate by maleate isomerase

Maleate isomerase (MI), a member of the Asp/Glu racemase superfamily, catalyzes cis-trans isomerization of the C2-C3 double bond in maleate to yield fumarate. Mutational studies, in conjunction with the structure of the C194A mutant of Nocardia farcinica MI cocrystallized with maleate, have revealed an unprecedented mode of catalysis for the superfamily in which the isomerization reaction is initiated by nucleophilic attack of cysteine at the double bond, yielding a covalent succinylcysteine-like intermediate.

Structure-function characterization and optimization of a plant-derived antibacterial peptide

Crushed seeds of the Moringa oleifera tree have been used traditionally as natural flocculants to clarify drinking water. We previously showed that one of the seed peptides mediates both the sedimentation of suspended particles such as bacterial cells and a direct bactericidal activity, raising the possibility that the two activities might be related. In this study, the conformational modeling of the peptide was coupled to a functional analysis of synthetic derivatives. This indicated that partly overlapping structural determinants mediate the sedimentation and antibacterial activities. Sedimentation requires a positively charged, glutamine-rich portion of the peptide that aggregates bacterial cells. The bactericidal activity was localized to a sequence prone to form a helix-loop-helix structural motif. Amino acid substitution showed that the bactericidal activity requires hydrophobic proline residues within the protruding loop. Vital dye staining indicated that treatment with peptides containing this motif results in bacterial membrane damage. Assembly of multiple copies of this structural motif into a branched peptide enhanced antibacterial activity, since low concentrations effectively kill bacteria such as Pseudomonas aeruginosa and Streptococcus pyogenes without displaying a toxic effect on human red blood cells. This study thus identifies a synthetic peptide with potent antibacterial activity against specific human pathogens. It also suggests partly distinct molecular mechanisms for each activity. Sedimentation may result from coupled flocculation and coagulation effects, while the bactericidal activity would require bacterial membrane destabilization by a hydrophobic loop.