Grey (2018) — Stem Loosening rTSA Systematic Review

Stem Loosening Rtsa Systematic Review

Grey·JBJS_Humeral·2018·Shoulder & Elbow

Summary

This systematic review and meta-analysis pooled outcomes from 75 studies on reverse shoulder arthroplasty. It asked whether cemented versus uncemented humeral fixation, follow-up duration, or surgical indication affect aseptic stem loosening. Data from 1,660 cemented and 805 uncemented stems were analyzed.

Study Snapshot

Design

Systematic review and meta-analysis

Setting: Groote Schuur Hospital, Cape Town

Funding: Industry fellowships (DePuy, Smith & Nephew)

Objective

Whether cement fixation, follow-up length, or etiology affect aseptic humeral stem loosening after RSA

Outcome(s)

Aseptic stem loosening, radiolucent lines, revision for loosening

Subjects

2,465 stems

1
660Cemented
805Uncemented

Inclusion

Clinical RSA studies reporting stem loosening
Any design or sample size
English language

Exclusion

Biomechanical, cadaveric, case reports, reviews
Stemless RSA, platform stems, registry data
Revisions performed for infection

Follow-up

Stratified <5 vs ≥5 years mean follow-up

Statistics

Chi-square testsHolm-Bonferroni correctionKappa statistic

Key Findings

Aseptic humeral stem loosening after RSA is rare, with an overall pooled rate of 1%. This confirms the stem is not the weak link in most RSAs.
Loosening rose with time — 2.0% at ≥5 years vs 0.8% at <5 years (p=0.01). Most RSA literature has only short to mid-term follow-up, so true long-term rates may be underestimated.
Cement made no difference to loosening or revision. Cemented stems loosened at 1.16% vs 0.75% uncemented (p=0.40, not significant). Fixation choice can be driven by other factors.
Cemented stems showed more humeral radiolucent lines (15.9% vs 9.5%, p=0.002). The authors caution that stress-shielding can mimic radiolucent lines around uncemented stems, muddying interpretation.
Etiology drove risk. The tumor subgroup had the highest loosening at 10.8% (4 of 37), followed by revision RSA at 3.7%. Both linked to proximal humeral bone loss.
Revision RSA loosened 6-fold more than primary RSA for cuff pathology (3.66% vs 0.61%, p=0.02). Monitor these patients closely.
No acute fracture or fracture sequelae stems loosened (0 of 497 and 0 of 199). Yet 41% of fracture sequelae stems showed radiolucent lines, so short follow-up may be masking future risk.

Board PearlAseptic humeral stem loosening after RSA is rare (1%), unaffected by cement, but driven by proximal bone loss — highest after tumor excision and revision.

Clinical Relevance

When you counsel a patient before RSA, the humeral stem is rarely the failure point — pooled aseptic loosening is only about 1%. The decision that actually matters is not cement versus no cement. Loosening and revision rates were statistically identical between the two, so fixation can be chosen on surgeon preference, bone quality, and future revision considerations.

What drives loosening is proximal humeral bone loss. Tumor excision (10.8%) and revision-of-failed-arthroplasty cases (3.7%) carry the real risk, because torsional forces concentrate at the shortened bone-cement interface. Translate this to practice: flag tumor and revision RSA patients for closer radiographic surveillance.

Be cautious reading radiolucent lines. Cemented stems show more of them, but stress-shielding mimics radiolucency around uncemented stems, and not all lines progress to clinical loosening.

Supplemental

Stem Loosening Rtsa Systematic Review

Stem Loosening Rtsa Systematic Review

Study Snapshot

Key Findings

Clinical Relevance

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