Does matching glenosphere size to patient height improve outcomes following reverse total shoulder arthroplasty?

Abstract

Introduction

Optimal biomechanics in reverse total shoulder arthroplasty (rTSA) are still a topic of debate. Although larger glenospheres have been linked with a theoretical improvement in the range of movement, results from clinical studies are mixed. We hypothesised that matching glenosphere diameter to patient height would result in greater improvements in post-operative range of motion (ROM) and patient-reported outcomes (PROMs).

Methods

An international database of rTSAs was analysed. After exclusions, 3318 rTSA patients were classified as short (<158 cm), average (158–173 cm) or tall(>173 cm). Outcomes were stratified for glenosphere size (small≤38 mm, large≥40 mm). Results were compared preoperatively and at 2 years.

Results

In short patients glenosphere diameter had no statistically significant impact on the degree of post-operative improvement for any ROM or PROM. Average height patients treated with small glenospheres had significantly more improvement in internal rotation (1.3 vs 1.0, p = 0.01), VAS pain (5.3 vs 4.8, p = 0.002), American Shoulder and Elbow Surgeons (47.8 vs 45.2, p = 0.03) and Shoulder Arthroplasty Smart (30.9 vs 28.2, p = 0.01) but significantly less improvement in constant score (31.7 vs 35.3, p = 0.009). Tall patients treated with small glenospheres had significantly more improvement in external rotation (21.2 vs 16.4, p = 0.01) and VAS pain scores (4.7 vs 4.3, p = 0.04).

Conclusions

While most significant differences favoured small glenospheres, the magnitude of these differences was small. Overall, patients of all heights can expect similar clinical improvements irrespective of glenosphere size.

Introduction

Reverse total shoulder arthroplasty (rTSA) has proven to be a reliable surgical option for the treatment of end-stage degenerative shoulder disease ¹ and now accounts for over half of all shoulder arthroplasty procedures captured by major national joint registries. ² rTSA has been shown to improve both patient range of movement (ROM) and patient-reported outcomes (PROMs).^1,3 Glenosphere diameter is one specific factor associated with the degree of improvement in these outcomes.^4–7

While early biomechanical studies demonstrated increased impingement-free ROM with larger glenosphere size^4,5 the reverse was noted during a subsequent cadaveric study. ⁸ Although increased glenosphere diameter has been linked with a better range of movement and less potential for scapular notching ⁸ the results from retrospective clinical studies remain mixed. While some studies have observed improvements in range of movement^6,7 and functional scores ⁹ with larger glenospheres, others have identified no statistical relationship between glenosphere diameter and range of movement or patient PROMs.^10–13

There is evidence for predictable surgeon preference for implanting comparatively smaller glenospheres into shorter patients and larger glenospheres into taller patients. ¹¹ This may be due to difficult access in smaller patients affecting ease of implantation or due to attempts to best recreate patients’ native anatomy. The cut-off value for the prosthesis used in this study, where a patient can be expected to receive a glenosphere of 40 mm diameter or larger, has been reported as 170 cm. ¹¹ By retrospectively analysing a large sample of RTSAs as three distinct cohorts we hoped to understand the effect of glenosphere size on short, average and tall patients, respectively. We hypothesise that patients at divergent ends of the height range might expect distinctly different changes in their post-operative ROM and PROMS when treated with either large or small glenospheres.

The purpose of this study is to analyse an international database of a single shoulder prosthesis to compare clinical outcomes associated with patients of short, average and tall height when outcomes are stratified by glenosphere diameter.

Methods

All shoulders were treated using a single arthroplasty system (Equinoxe; Exactech, Gainesville, FL, USA). This 145° onlay system is provided in five glenosphere diameter options (36, 38, 40, 42 and 46 mm), with 2 mm of lateral offset for all standard glenosphere sizes and 6 mm of lateral offset additionally available for the 36, 38, 40 and 42 mm sizes. Glenosphere size was chosen intraoperatively based on surgeon preference. No single glenosphere size is officially recommended based on any patient characteristics.

The international database for this prosthesis was analysed to evaluate the impact of patient height on clinical outcomes at latest 2-year minimum clinical follow-up. Primary RTSA patients from May 2007 to April 2021 were included in this study if they had available demographic information related to height to classify as short (<158 cm), average (158–173 cm) or tall (>173 cm) stature and had outcome data to a 2-year minimum follow-up. Patients with a history of revision arthroplasty, humeral fractures, Rheumatoid arthritis diagnosis, or previous infections were excluded.

Patients were evaluated pre-operatively and post-operatively using ROM and PROMs. ROM measurements included forward elevation (FE), abduction and external rotation (ER) measured in degrees. Internal rotation (IR) was assessed and recorded on an objective points scale. One point was awarded for internal rotation to the level of the hip, two points for the level of the buttock, three points for the sacrum, four points for the level of the L4/5 disc, five points for between L3 and L1, six points if T12 was reached and seven if T7 could be reached. PROMs included the American Shoulder and Elbow Surgeons (ASES) score, Constant score, Shoulder Arthroplasty Smart (SAS) score, ¹⁴ simple shoulder test (SST) score and University of California at Los Angeles (UCLA) score.

To analyse the impact of patient height on outcomes, stature cohorts were compared at the latest follow-up when stratified by glenosphere diameter into two cohorts: Small glenospheres were categorised as 38 mm diameter or less and large glenospheres categorised as 40 mm diameter or more. The pre-operative, latest follow-up and pre-to-post-operative improvement of clinical outcomes of each cohort, as well as the complication and revision rates were compared using student's t-test for continuous variables and a Wilcoxon-rank-sum test for ordinal variables, with p<0.05 denoting significance.

Results

The clinical outcomes of 3318 (1993 F/1325 M) primary RTSA patients were analysed in this study. 787 (764 F/23 M) primary RTSA patients were included in the short-stature cohort, 1614 (1154 F/460 M) primary RTSA patients were in the average-stature cohort and 917 (75 F/842 M) primary RTSA patients were in the tall-stature cohort.

Several demographic, operative and implant size differences were observed between cohorts (Table 1). Most notably, small-stature patients were predominately (97.1%) female and received a 38 mm glenosphere or smaller 88.9% of the time; whereas tall-stature patients were predominately (91.8%) male and received a 40 mm glenosphere or larger 76.1% of the time. By comparison, average-stature patients were 71.5% female and received a 38 mm glenosphere or smaller 68.5% of the time. The comorbidities recorded in each cohort were not statistically significantly different.

Table 1.

Comparison of RTSA patients of short, average and tall height, pre-operative demographic differences.

	Short (n = 787)	Average (n = 1614)	Tall (n = 917)
Mean patient height	153.4	165.5	179.9
Mean age	73.7	72.2	70.5
Gender	97.1% F	71.5% F	8.2% F
BMI	29.7	28.8	29
% No comorbidities	33.20%	32.10%	29.30%
Received small diameter glenosphere (≤38 mm)	89%	69%	24%

At the latest follow-up, short-stature patients with 38 mm glenospheres or smaller had significantly more FE (139.9 vs 132.6, p = 0.0477) and significantly higher shoulder arthroplasty smart scores (74.6 vs 70.6, p = 0.0099) than those with 40 mm glenospheres or larger (Table 2). However, when taking into account the pre-operative differences between cohorts, glenosphere diameter had no statistically significant impact on the overall improvement in clinical outcomes for any measure of ROM or PROMS for short-stature patients.

Table 2.

Comparison of RTSA patients of short height with 38 mm glenospheres or smaller versus patients of short height with 40 mm glenospheres or larger diameter, pre-operative, at latest follow-up and pre-to-post-operative improvement.

Short stature patients
	Pre-operative			Latest follow-up			Pre-op vs LFU improvement			MCID14,16,22,23
	≤38 mm	≥40 mm	(38 mm vs 40 mm)	≤38 mm	≥40 mm	(38 mm vs 40 mm)	≤38 mm	≥40 mm	(38 mm vs 40 mm)
Abduction	79.0 ± 36.2	72.6 ± 32.3	p0.1215	120.4 ± 32.6	118.4 ± 32.0	p0.6102	42.7 ± 40.0	45.8 ± 42.9	p0.5395	4.4
Forward elevation	92.7 ± 39.8	79.7 ± 34.9	p0.0044	139.9 ± 28.9	132.6 ± 32.7	p0.0477	47.0 ± 41.3	53.7 ± 44.9	p0.2097	8.5
IR score	3.2 ± 1.9	2.7 ± 1.8	p0.0508	4.1 ± 1.8	3.8 ± 1.8	p0.2001	0.9 ± 2.1	0.8 ± 1.9	p0.8474	−0.1
Ext. rotation	21.9 ± 20.3	18.3 ± 19.6	p0.1190	37.2 ± 17.6	34.6 ± 20.3	p0.2324	15.7 ± 17.6	17.0 ± 24.3	p0.6466	2.6
VAS pain	6.6 ± 2.1	6.3 ± 2.5	p0.1726	1.3 ± 2.2	1.3 ± 2.2	p0.9181	5.4 ± 2.2	5.0 ± 3.1	p0.2727	−1.3
SST	3.3 ± 2.6	3.4 ± 2.8	p0.8307	9.2 ± 2.8	8.5 ± 3.2	p0.0850	6.0 ± 3.3	5.2 ± 3.9	p0.0756	1.8
Constant	35.9 ± 14.3	32.7 ± 14.7	p0.1038	64.7 ± 14.3	62.1 ± 15.5	p0.1816	28.8 ± 17.0	30.6 ± 19.4	p0.4967	3
ASES	33.2 ± 15.4	34.1 ± 17.8	p0.6233	80.2 ± 19.5	78.2 ± 20.1	p0.3750	47.3 ± 21.9	45.1 ± 25.6	p0.4119	11.2
SAS	46.0 ± 12.5	43.1 ± 13.2	p0.0617	74.6 ± 12.1	70.4 ± 13.4	p0.0099	28.3 ± 15.2	28.9 ± 18.1	p0.7884	4.9

Statistical significance values are in bold.

At the latest follow-up, average-stature patients treated with 38 mm glenospheres or smaller had significantly more internal rotation (4.5 vs 3.9, p<0.0001), ER (39.6 vs 37.1, p=0.0172) and significantly higher shoulder arthroplasty smart scores (76.2 vs 74.4, p=0.00212) (Table 3). When taking into account pre-operative differences, average-stature patients with 38 mm glenospheres or smaller had significantly more improvement in internal rotation (1.3 vs 10, p=0.0118), VAS pain (5.3 vs 4.8, p=0.0356), SST (6.3 vs 5.9, p=0.0020), ASES (47.8 vs 45.2, p=0.0374) and SAS Score (30.9 vs 28.2, p=0.0107) than patients with 40 mm glenospheres or larger diameter. However, patients with 40 mm glenospheres or larger diameter had significantly more improvement in the constant score (35.3 vs 31.7, p=0.0092) (Table 3).

Table 3.

Comparison of RTSA patients of average height with 38 mm glenospheres or smaller versus patients of average height with 40 mm glenospheres or larger diameter, pre-operative, at latest follow-up and pre-to-post-operative improvement.

Average stature patients
	Pre-operative			Latest follow up			Pre-op vs LFU improvement			MCID14,16,22,23
	≤38 mm	≥40 mm	(38 mm vs 40 mm)	≤38 mm	≥40 mm	(38 mm vs 40 mm)	≤38 mm	≥40 mm	(38 mm vs 40 mm)
Abduction	76.0 ± 37.6	72.5 ± 39.1	p0.1024	124.3 ± 32.4	123.4 ± 32.2	p0.6404	48.2 ± 40.9	48.4 ± 41.0	p0.9121	4.4
Forward elevation	89.7 ± 39.9	87.2 ± 40.0	p0.2572	142.3 ± 27.8	143.4 ± 27.7	p0.4988	51.9 ± 42.8	54.0 ± 43.3	p0.3971	8.5
IR score	3.2 ± 1.9	3.0 ± 1.8	p0.1469	4.5 ± 1.7	3.9 ± 1.8	p<0.0001	1.3 ± 2.2	1.0 ± 2.1	p0.0118	−0.1
Ext. rotation	20.7 ± 22.4	18.4 ± 22.4	p0.0638	39.6 ± 17.7	37.1 ± 18.7	p0.0172	19.6 ± 23.2	18.3 ± 23.6	p0.3817	2.6
VAS pain	6.4 ± 2.2	6.0 ± 2.2	p0.0005	1.2 ± 2.0	1.2 ± 2.1	p0.7132	5.3 ± 2.7	4.8 ± 2.6	p0.0020	−1.3
SST	3.3 ± 2.7	3.8 ± 2.8	p0.0039	9.7 ± 2.7	9.8 ± 2.8	p0.4151	6.3 ± 3.4	5.9 ± 3.6	p0.0809	1.8
Constant	35.4 ± 14.2	35.3 ± 14.3	p0.9436	68.3 ± 14.6	69.5 ± 15.0	p0.2368	31.7 ± 18.1	35.3 ± 16.8	p0.0092	3
ASES	34.7 ± 15.6	37.5 ± 14.7	p0.0012	82.4 ± 18.1	82.8 ± 19.2	p0.6738	47.8 ± 21.6	45.2 ± 21.3	p0.0374	11.2
SAS	45.6 ± 12.2	46.3 ± 11.8	p0.3468	76.2 ± 12.1	74.4 ± 12.9	p0.0212	30.9 ± 15.2	28.2 ± 15.1	p0.0107	4.9

Statistical significance values are in bold.

At the latest follow-up, tall-stature patients treated with 38 mm glenospheres or smaller had significantly more internal rotation (4.6 vs 3.9, p<0.0001), however, they had significantly better internal rotation preoperatively (Table 4). At the latest follow-up, tall-stature patients treated with 38 mm glenospheres or smaller had significantly more ER (43.0 vs 38.9, p=0.0061) and significantly more improvement in ER (21.2 vs 16.4, p=0.0161). They did however have significantly lower constant scores at last follow-up (68.7 vs 72.2, p=0.0370) compared to patients treated with 40 mm glenospheres or larger. Tall-stature patients with 38 mm glenospheres or smaller had significantly more improvement in VAS pain scores (4.7 vs 4.3, p=0.0356) than patients treated with 40 mm glenospheres or larger.

Table 4.

Comparison of RTSA patients of tall height with 38 mm glenospheres or smaller versus patients of tall height with 40 mm glenospheres or larger diameter, pre-operative, at latest follow-up and pre-to-post-operative improvement.

Tall stature patients
	Pre-operative			Latest follow up			Pre-op vs LFU improvement			MCID14,16,22,23
	≤38 mm	≥40 mm	(38 mm vs 40 mm)	≤38 mm	≥40 mm	(38 mm vs 40 mm)	≤38 mm	≥40 mm	(38 mm vs 40 mm)
Abduction	86.5 ± 41.9	85.0 ± 40.5	p0.6433	130.9 ± 32.2	129.4 ± 32.1	p0.5895	45.2 ± 40.4	44.5 ± 42.3	p0.8504	4.4
Forward elevation	97.4 ± 40.8	96.4 ± 40.7	p0.7511	141.6 ± 27.1	143.7 ± 27.9	p0.3905	45.0 ± 41.4	46.7 ± 42.2	p0.6447	8.5
IR score	3.5 ± 1.9	3.2 ± 1.8	p0.0295	4.6 ± 1.6	3.9 ± 1.7	p<0.0001	1.0 ± 2.1	0.6 ± 2.1	p0.0535	−0.1
Ext. rotation	24.0 ± 21.1	22.4 ± 21.8	p0.3552	43.0 ± 16.7	38.9 ± 17.1	p0.0061	21.2 ± 21.2	16.4 ± 22.7	p0.0161	2.6
VAS pain	5.9 ± 2.3	5.4 ± 2.4	p0.0194	1.3 ± 2.2	1.2 ± 2.1	p0.8110	4.7 ± 2.7	4.3 ± 2.9	p0.0356	−1.3
SST	4.4 ± 2.8	4.9 ± 2.9	p0.0455	10.1 ± 2.4	10.4 ± 2.5	p0.2558	5.9 ± 3.1	5.4 ± 3.4	p0.1183	1.8
Constant	41.0 ± 15.1	40.8 ± 15.1	p0.8820	68.7 ± 15.9	72.2 ± 15.0	p0.0370	28.7 ± 19.8	31.9 ± 17.8	p0.1700	3
ASES	39.8 ± 16.1	42.6 ± 16.7	p0.0407	83.2 ± 19.4	84.4 ± 19.0	p0.4186	44.0 ± 21.3	41.5 ± 22.9	p0.1908	11.2
SAS	49.4 ± 12.8	49.4 ± 12.5	p0.9851	76.6 ± 11.9	75.4 ± 11.9	p0.2690	28.1 ± 14.4	25.8 ± 14.7	p0.1067	4.9

Statistical significance values are in bold.

 Table 5 reports low complication, dislocation and revision rates with both small and large glenospheres, regardless of short or tall patient height. The only statistically significant difference noted was for average-height patients. At the latest follow-up, average-height patients had a 2.4% revision rate when treated with a larger glenosphere, compared to a 1.1% revision rate in the smaller glenosphere cohort.

Table 5.

Complication, dislocation and revision rate comparison of RTSA patients of short, average and tall height with 38 mm glenospheres or smaller diameter versus patients of short, average and tall height with glenospheres 40 mm or larger diameter.

	Short stature patients			Average stature patients			Tall stature patients
	≤38 mm	≥40 mm	38 mm vs ≥40 mm	≤38 mm	≥40 mm	38 mm vs ≥40 mm	≤38 mm	≥40 mm	38 mm vs ≥40 mm
Complication rate at LFU	3.1%	2.3%	p0.6664	2.9%	3.1%	p0.7858	3.2%	4.6%	p0.375
Dislocation rate at LFU	0.6%	1.1%	p0.5230	0.5%	0.4%	p0.8660	1.2%	1.1%	p0.953
Revision rate at LFU	0.9%	2.3%	p0.2066	1.1%	2.4%	p0.0499	2.3%	3.7%	p0.3035

Statistical significance values are in bold.

 Table 6 displays the distribution in the use of expanded glenospheres across the patient cohorts. The only statistically significant difference was observed in the short-stature cohort.

Table 6.

Percent usage of expanded glenospheres for short, average and tall height patients with 38 mm glenospheres or smaller diameter versus patients of short, average and tall height with glenospheres 40 mm or larger diameter.

	Short stature patients			Average stature patients			Tall stature patients
	≤38 mm	≥40 mm	38 mm vs ≥40 mm	≤38 mm	≥40 mm	38 mm vs ≥40 mm	≤38 mm	≥40 mm	38 mm vs ≥40 mm
% Usage of expanded glenospheres	3.7%	13.0%	p0.001	4.2%	5.0%	p0.477	8.5%	9.6%	p0.630

Statistical significance values are in bold.

Figure 1 collates and visually represents all statistically significant improvement differences observed between small and large glenospheres across all cohorts.

Figure 1.

All statistically significant differences in improvement between glenosphere sizes across all height cohorts. (IR points have been scaled up by a magnitude of 10.)

Discussion

The results of this study of 3318 RTSAs demonstrate that positive clinical outcomes at 2-year minimum follow-up can be achieved for patients of small, average and tall height using an onlay rTSA system. A comparison of clinical outcomes and rage of motion when stratified by glenosphere diameter identified only a few small differences in clinical outcomes and ROM, confirming that RTSA using an onlay system is an effective treatment option for patients across the height range. Overall complication, dislocation and revision rates remain low in all height cohorts despite variance in glenosphere size.

Multiple biomechanical factors have been associated with improvement in clinical outcomes following rTSA. Humeral version, neck-shaft-angle and lateralisation along with glenoid inferiorisation, eccentricity, overhang, version and diameter are all factors that have been associated with improved impingement-free ROM. ¹⁵ Biomechanical studies evaluating the effect of increased glenosphere diameter and lateralisation of the centre of rotation reported larger impingement free motion and less potential for scapular notching.^4,5,8,15 However, quantifying the role that a singular change in glenosphere diameter plays on post-operative clinical ROM and outcomes is yet to reach consensus within the literature.

Several retrospective clinical studies have reported better post-operative outcomes with larger glenosphere sizes. Bloch et al. reported significantly more FE improvements in patients treated with larger glenospheres but no significant differences in ER or IR. ⁶ Their sample size was small at 133 RTSA and the authors concluded that the improvement in FE did not reach the minimally clinically important difference. Muller et al. analysed another small sample of 68 rTSAs post-operatively and described superior ER and abduction in the larger glenosphere group but found no significant changes in functional outcomes or incidence of scapular notching. ⁷ Mollon et al. analysed the outcomes of 297 RTSAs and found that larger glenospheres were associated with significantly more improvement in FE and ER. ⁹ Oak et al. found that increased glenosphere size significantly predicted more improvement in Vetrans-RAND-12 health score but not in other clinical outcomes. ¹⁷ Sabesan retrospectively analysed 148 RTSAs, finding no significant impact of glenosphere size on either ROM or PROM score. ¹⁰ Similarly Hochreiter et al. found glenosphere diameter had no significant impact on IR in a 52 patient cohort. ¹² Schoch et al. were the only authors to evaluate post-operative ROM and PROMs as a function of both glenosphere diameter and patient height but again found no clear statistical differences across a continuous 612 RTSA cohort. ¹¹ While each study reports positive results, our results appear incongruous to the previous studies as we did not find that larger glenosphere size resulted in superior post-operative outcomes. Positive post-operative improvements were observed irrespective of glenosphere diameter and though a few statistically significant differences were observed, the magnitude of differences was small.

The key outcome focused on in our analysis is the degree of improvement observed in each cohort when taking into account preoperative differences. For example, patients treated with a small glenosphere in the short cohort, achieved higher postoperative FE values. However, when considering the higher preoperative FE values for these patients, there was no statistical difference in the amount of improvement postoperatively.

In the short cohort, glenosphere diameter seemed to have no statistically significant predictive value for the degree post operative improvement in ROM or PROMS. However, smaller glenospheres in the average cohort were associated with significantly more improvement in ASES, SAS and VAS pain scores, yet significantly less improvement in the Constant score. In the tall cohort, we observed significantly more improvement in ER and VAS pain scores with smaller glenospheres which may be counterintuitive given that taller patients have presumed larger native anatomy.

In this study, more improvement in Constant score was associated with larger glenospheres, whereas more improvement in ASES and SAS scores was seen with smaller glenospheres. The constant score defines a normal shoulder as that of a 25-year-old male, ¹⁸ which potentially introduces an element of inherent age and gender bias. Floor effects with the strength component of the Constant score ¹⁹ have been linked to the measurements being performed at 90° of abduction, which some patients fail to achieve before or after surgery.^20,21 Given the gender imbalance between our cohorts, with the tall cohort being predominantly male and receiving large glenospheres, gender is a significant confounder and possibly responsible for the association between improved constant score and large glenospheres.

Relevant minimally clinically important difference (MCID) values following rTSA are displayed in Tables 2–4.^14,16,22,23 Improvement in Constant score and IR, in the average stature cohort, were the only statistically significant values to reach the MCID threshold. This suggests that the other observed differences, while statistically significant, may not be clinically important.

Table 6 demonstrates the usage of expanded glenospheres, which give +4 mm of centre of rotation lateralisation, for a given glenosphere diameter. There were no significant differences in usage of expanded glenospheres for the average and tall stature cohorts. However, expanded glenosphere usage was significantly lower for smaller glenospheres (3.7% vs 13.0%, p < 0.001) in the short cohort. Although another confounder, this single variable is small in magnitude and confined to only the short cohort. It therefore likely does not explain the observed findings.

Although revision rates overall remained low despite variance in glenosphere size, we observed a small but statistically significant increase in revision rate when average patients were treated with larger glenospheres. Further work and analysis may help to explain the cause of this difference.

This study has several limitations. First, the design of this study is retrospective in nature with no blinding of surgeons to glenosphere diameter. The different stature cohorts had numerous differences in pre-operative characteristics, implant and surgical factors, which may have confounded our findings. As an example, we did not stratify clinical outcomes in each patient height cohort by the usage of augmented glenoid baseplates, where 26.7% of short patients had an augmented baseplate, 30.0% of average-height patients had an augmented baseplate and 42.8% of tall patients had an augmented baseplate; these differences in native glenoid deformity and implant correction between cohorts may have influenced results.

Perhaps most significantly, we did not attempt to normalise gender or age. Specifically, regarding gender, 97.1% of the short-stature cohort were female as compared to only 8.2% of the tall-stature cohort. Regarding differences in age, the short-stature cohort was significantly older than the average-stature and tall-stature cohort. As these difference in gender, age, implant size and surgical technique may influence the observed differences in pre-operative and post-operative outcomes rather than glenosphere diameter alone; future work should aim to compare clinical outcomes for each glenosphere size in each patient height cohort when matching for age and gender.

Conclusions

The optimal biomechanics of RTSA for a given patient morphology is still a topic of debate. While lateralisation with RTSA may improve ROM^24,25 it can be achieved by adjusting a variety of components such as humeral liner thickness, baseplate offset (e.g., standard or augmented), or glenosphere thickness/diameter depending on the particular implant system. Our study demonstrated that patients of short, average and tall height achieved similar levels of clinical improvement, regardless of glenosphere diameter and these positive results were achieved in each cohort despite pre-operative, demographic and surgical differences. Future work should attempt to more quantifiably analyse differences in other technical factors, such as glenoid lateralisation, humeral version and soft tissue tensioning, as these parameters may play a more important role than glenosphere size alone.