To investigate whether arthroscopic lateral acromion resection can sufficiently reduce the critical shoulder angle (CSA) without damaging deltoid muscle insertion.
Ninety patients who underwent arthroscopic rotator cuff (RC) repair were retrospectively analysed. According to the preoperative CSA, patients were categorized as Group I (CSA < 35°) and Group II (CSA ≥ 35°). Additional arthroscopic lateral acromion resection was performed in Group II. The CSA was measured 1 week postoperatively, while RC integrity and the deltoid attachment were assessed at 3, 6 and 12 months via ultrasound. Deltoid function was evaluated using the Akimbo test, in which patients place their hands on the iliac crest with abduction in the coronal plane and internal rotation of the shoulder joint while simultaneously flexing the elbow joint and pronating the forearm.
Large and massive RC tears were more prevalent in Group II (p = 0.017). In both groups, the CSA reduction was statistically significant (Group I = 1°: range 0°–3°, Group II = 3.7°: range 1°–8°; p < 0.001). When the preoperative CSA was > 40°, the respective postoperative CSA remained > 35° in 83.3% of cases (p < 0.001). Final shoulder strength was correlated with the amount of CSA reduction (rho = 0.41, p = 0.002). The postoperative CSA was higher, but not significantly different (n.s.), in patients with re-torn (36°, range 32°–40°) than with healed RC (33°, range 26°–38°). No clinical detachment or hypotrophy of the deltoid was observed with the Akimbo test and ultrasound evaluation.
Arthroscopic lateral acromion resection is a safe procedure without affecting deltoid muscle origin or function, and it is effective in significantly reducing the CSA. However, the CSA cannot always be reduced to < 35°, especially in patients with preoperative CSA values > 40°.
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Critical shoulder angle
Arthroscopic lateral acromioplasty
Rotator cuff tear
Distal clavicle resection
Body mass index
Range of motion
Visual analogue scale
Simple shoulder test
Subjective shoulder value
American Shoulder and Elbow Score
Critical acromial point
Altintas B, Kääb M, Greiner S (2016) Arthroscopic lateral acromion resection (ALAR) optimizes rotator cuff tear relevant scapula parameters. Arch Orthop Trauma Surg 136:799–804
Banas MP, Miller RJ, Totterman S (1995) Relationship between the lateral acromion angle and rotator cuff disease. J Shoulder Elbow Surg 4:454–461
Barth J, Fotiadis E, Barthelemy R, Genna S, Saffarini M (2015) Ultrasonic evaluation of the repair integrity can predict functional outcomes after arthroscopic double-row rotator cuff repair. Knee Surg Sports Traumatol Arthrosc 23:376–385
Bonnevialle N, Colombi R, Girard M, Azoulay V, Martel M, Mansat P (2018) L’acromioplastie diminue-t-elle le critical shoulder angle? Revue Chir Orthop Traumatol 104:S96
Burkhart SS, Brady PC (2006) Arthroscopic subscapularis repair: surgical tips and pearls A to Z. Arthroscopy 22:1014–1027
Cofield RH (1985) Rotator cuff disease of the shoulder. J Bone Joint Surg Am 67:974–979
Collin P, Abdullah A, Kherad O, Gain S, Denard PJ, Lädermann A (2015) Prospective evaluation of clinical and radiologic factors predicting return to activity within 6 months after arthroscopic rotator cuff repair. J Shoulder Elbow Surg 24:439–445
Collin P, Matsumura N, Lädermann A, Denard PJ, Walch G (2014) Relationship between massive chronic rotator cuff tear pattern and loss of active shoulder range of motion. J Shoulder Elbow Surg 23:1195–1202
Daggett M, Werner B, Collin P, Gauci M-O, Chaoui J, Walch G (2015) Correlation between glenoid inclination and critical shoulder angle: a radiographic and computed tomography study. J Shoulder Elbow Surg 24:1948–1953
Engelhardt C, Farron A, Becce F, Place N, Pioletti DP, Terrier A (2017) Effects of glenoid inclination and acromion index on humeral head translation and glenoid articular cartilage strain. J Shoulder Elbow Surg 26:157–164
Fehringer EV, Sun J, VanOeveren LS, Keller BK, Matsen FA (2008) Full-thickness rotator cuff tear prevalence and correlation with function and co-morbidities in patients sixty-five years and older. J Shoulder Elbow Surg 17:881–885
Fujihara Y, Doi K, Dodakundi C, Hattori Y, Sakamoto S, Takagi T (2012) Simple clinical test to detect deltoid muscle dysfunction causing weakness of abduction—“Akimbo” test. J Reconstr Microsurg 28:375–379
Gagey O, Hue E (2000) Mechanics of the deltoid muscle. A new approach. Clin Orthop Relat Res 375:250–257
Garcia GH, Liu JN, Degen RM, Johnson CC, Wong AC, Dines DM, Gulotta LV, Dines JS (2017) Higher critical shoulder angle increases the risk of retear after rotator cuff repair. J Shoulder Elbow Surg 26:241–245
Gerber C, Catanzaro S, Betz M, Ernstbrunner L (2018) Arthroscopic correction of the critical shoulder angle through lateral acromioplasty: a safe adjunct to rotator cuff repair. Arthroscopy 34:771–780
Gerber C, Snedeker JG, Baumgartner D, Viehöfer AF (2014) Supraspinatus tendon load during abduction is dependent on the size of the critical shoulder angle: a biomechanical analysis. J Orthop Res 32:952–957
Goutallier D, Postel JM, Bernageau J, Lavau L, Voisin MC (1994) Fatty muscle degeneration in cuff ruptures. Pre- and postoperative evaluation by CT scan. Clin Orthop Relat Res 304:78–83
Hamada K, Fukuda H, Mikasa M, Kobayashi Y (1990) Roentgenographic findings in massive rotator cuff tears. A long-term observation. Clin Orthop Relat Res 254:92–96
Hashimoto T, Nobuhara K, Hamada T (2003) Pathologic evidence of degeneration as a primary cause of rotator cuff tear. Clin Orthop Relat Res 415:111–120
Hughes RE, Bryant CR, Hall JM, Wening J, Huston LJ, Kuhn JE, Carpenter JE, Blasier RB (2003) Glenoid inclination is associated with full-thickness rotator cuff tears. Clin Orthop Relat Res 407:86–91
Kaiser D, Bachmann E, Gerber C, Meyer DC (2018) Influence of the site of acromioplasty on reduction of the critical shoulder angle (CSA)—an anatomical study. BMC Musculoskelet 19:371
Karns MR, Jacxsens M, Uffmann WJ, Todd DC, Henninger HB, Burks RT (2018) The critical acromial point: the anatomic location of the lateral acromion in the critical shoulder angle. J Shoulder Elbow Surg 27:151–159
Katthagen JC, Marchetti DC, Tahal DS, Turnbull TL, Millett PJ (2016) The effects of arthroscopic lateral acromioplasty on the critical shoulder angle and the anterolateral deltoid origin: an anatomic cadaveric study. Arthroscopy 32:569–575
Kukkonen J, Kauko T, Vahlberg T, Joukainen A, Äärimaa V (2013) Investigating minimal clinically important difference for Constant score in patients undergoing rotator cuff surgery. J Shoulder Elbow Surg 22:1650–1655
Li H, Chen Y, Chen J, Hua Y, Chen S (2018) Large critical shoulder angle has higher risk of tendon retear after arthroscopic rotator cuff repair. Am J Sports Med 46:1892–1900
Marchetti DC, Katthagen JC, Mikula JD, Montgomery SR, Tahal DS, Dahl KD, Turnbull TL, Millett PJ (2017) Impact of arthroscopic lateral acromioplasty on the mechanical and structural integrity of the lateral deltoid origin: a cadaveric study. Arthroscopy 33:511–517
Minagawa H, Yamamoto N, Abe H, Fukuda M, Seki N, Kikuchi K, Kijima H, Itoi E (2013) Prevalence of symptomatic and asymptomatic rotator cuff tears in the general population: from mass-screening in one village. J Orthop 10:8–12
Moor BK, Bouaicha S, Rothenfluh DA, Sukthankar A, Gerber C (2013) Is there an association between the individual anatomy of the scapula and the development of rotator cuff tears or osteoarthritis of the glenohumeral joint? A radiological study of the critical shoulder angle. Bone Joint J 95-B:935–941
Moor BK, Kuster R, Osterhoff G, Baumgartner D, Werner CML, Zumstein MA, Bouaicha S (2016) Inclination-dependent changes of the critical shoulder angle significantly influence superior glenohumeral joint stability. Clin Biomech (Bristol Avon) 32:268–273
Moor BK, Röthlisberger M, Müller DA, Zumstein MA, Bouaicha S, Ehlinger M, Gerber C (2014) Age, trauma and the critical shoulder angle accurately predict supraspinatus tendon tears. Orthop Traumatol Surg Res 100:489–494
Neer CS (1972) Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg Am 54:41–50
Nyffeler RW, Werner CML, Sukthankar A, Schmid MR, Gerber C (2006) Association of a large lateral extension of the acromion with rotator cuff tears. J Bone Joint Surg Am 88:800–805
Ozaki J, Fujimoto S, Nakagawa Y, Masuhara K, Tamai S (1988) Tears of the rotator cuff of the shoulder associated with pathological changes in the acromion. A study in cadavera. J Bone Joint Surg Am 70:1224–1230
Park TS, Park DW, Kim SI, Kweon TH (2001) Roentgenographic assessment of acromial morphology using supraspinatus outlet radiographs. Arthroscopy 17:496–501
Patte D (1990) Classification of rotator cuff lesions. Clin Orthop Relat Res 254:81–86
Sano H, Ishii H, Yeadon A, Backman DS, Brunet JA, Uhthoff HK (1997) Degeneration at the insertion weakens the tensile strength of the supraspinatus tendon: a comparative mechanical and histologic study of the bone-tendon complex. J Orthop Res 15:719–726
Sonnabend DH, Yu Y, Howlett CR, Harper GD, Walsh WR (2001) Laminated tears of the human rotator cuff: a histologic and immunochemical study. J Shoulder Elbow Surg 10:109–115
Soslowsky LJ, Thomopoulos S, Esmail A, Flanagan CL, Iannotti JP, Williamson JD, Carpenter JE (2002) Rotator cuff tendinosis in an animal model: role of extrinsic and overuse factors. Ann Biomed Eng 30:1057–1063
Spiegl UJ, Horan MP, Smith SW, Ho CP, Millett PJ (2016) The critical shoulder angle is associated with rotator cuff tears and shoulder osteoarthritis and is better assessed with radiographs over MRI. Knee Surg Sports Traumatol Arthrosc 24:2244–2251
Tempelhof S, Rupp S, Seil R (1999) Age-related prevalence of rotator cuff tears in asymptomatic shoulders. J Shoulder Elbow Surg 8:296–299
Tétreault P, Krueger A, Zurakowski D, Gerber C (2004) Glenoid version and rotator cuff tears. J Orthop Res 22:202–207
Tonotsuka H, Sugaya H, Takahashi N, Kawai N, Sugiyama H, Marumo K (2017) Target range of motion at 3 months after arthroscopic rotator cuff repair and its effect on the final outcome. J Orthop Surg 25:230949901773042
Viehöfer AF, Gerber C, Favre P, Bachmann E, Snedeker JG (2016) A larger critical shoulder angle requires more rotator cuff activity to preserve joint stability. J Orthop Res 34:961–968
Yamamoto A, Takagishi K, Osawa T, Yanagawa T, Nakajima D, Shitara H, Kobayashi T (2010) Prevalence and risk factors of a rotator cuff tear in the general population. J Shoulder Elbow Surg 19:116–120
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Olmos, M.I., Boutsiadis, A., Swan, J. et al. Lateral acromioplasty cannot sufficiently reduce the critical shoulder angle if preoperatively measured over 40°. Knee Surg Sports Traumatol Arthrosc 29, 240–249 (2021). https://doi.org/10.1007/s00167-020-05951-4
- Critical shoulder angle
- Rotator cuff
- Rotator cuff retear
- Lateral acromioplasty
- Deltoid insertion