Stiffness of the shoulder following primary anatomic total shoulder arthroplasty (ATSA) and reverse total shoulder arthroplasty (RTSA) is poorly defined and often underreported as a unique surgical complication but is a common reason for dissatisfaction in patient-reported outcome studies.¹,²,³,⁴,⁵,⁶,⁷,⁸,⁹,¹⁰,¹¹ In a comprehensive review of complications of shoulder arthroplasty in 19,000 cases, stiffness was not listed as a unique complication.¹² Further confusing this issue, shoulder stiffness is often merely one of several factors accounting for failure following shoulder arthroplasty.

The purpose of this chapter is to define shoulder stiffness as a unique complication following shoulder arthroplasty; review the preoperative, intraoperative, and postoperative causes of stiffness; and provide an overview of the various treatments of shoulder stiffness based on etiology.

Stiffness as a unique complication following total shoulder arthroplasty may be defined as severe limitation of passive range of motion sufficient to compromise the basic activities of daily living necessary for independent self-care. A 2012 study quantified the range of motion required to perform the activities assessed by three validated shoulder patient-reported outcome measures: American Shoulder and Elbow Surgeons Score, the Simple Shoulder Test, and the University of Pennsylvania Shoulder Score.¹³ The average motion required to perform 10 functional activities were flexion, 121°; extension, 46°; abduction, 128°; cross body adduction, 116°; external rotation at 90° abduction, 59°; and internal rotation with the arm at the side, 102°. External rotation with the arm at the side was not recorded, nor was the correlation of humeral internal rotation with the common clinical measurement of internal rotation, ie, posterior reach (the highest midline spinal segment reached by the tip of the hitch-hiking thumb). The authors concluded that full range of motion of the shoulder is not required to perform the routine activities of daily living as defined in these three shoulder-specific patient-reported outcome measures. Hence, one could define shoulder stiffness as a complication following shoulder arthroplasty as range of motion less than the functional range of motion reported in the study.

Another definition of shoulder stiffness is the range of motion accounting for failure following total shoulder arthroplasty as reported by various investigators. In his 1982 report, Neer defined an unsatisfactory result following ATSA as <90° elevation and <25° external rotation,¹⁴ although the basis for these parameters was not discussed. Reporting on the characteristics of 139 failed shoulder arthroplasties, Hasan et al defined stiffness as the inability to perform activities relating to shoulder mobility as components of the Simple Shoulder Test: tuck in shirt, place hand behind head, place coin on shelf, and wash opposite shoulder.⁵

Another definition of shoulder stiffness to consider is the degree of limitation of motion that would indicate surgical intervention. Thorsness and Romeo recommended arthroscopic release for postarthroplasty patients with less than 90° forward flexion and less than 20° external rotation in the absence of component malposition or infection.¹⁵ Finally, in a study investigating severe preoperative external rotation deficits and RTSA outcomes, Carafino and coauthors defined stiffness as external rotation <20°.¹⁶

The lack of consensus on the definition of stiffness following shoulder arthroplasty contributes to its underreporting in the orthopedic literature. There are no accepted criteria for the degree of limitation of motion following shoulder arthroplasty that would qualify as a unique complication. Numerous reports of complications of shoulder arthroplasty either have not even included stiffness as a reason for failure or, when listed as a complication requiring revision surgery, have reported stiffness at a very low rate of 0.3% to 1%.¹,¹⁶ On the other hand, reporting on the reasons for patient dissatisfaction following shoulder arthroplasty, Franta and colleagues have stated that stiffness of the shoulder is the most common complaint, occurring in up to 74% of patients.³

For the purpose of this discussion, the degree of limitation of passive range of motion to define stiffness as a unique complication and a cause for a poor outcome following shoulder arthroplasty should be less than the range of motion required for functional use as described in the report of Namdari et al and, based
on the several studies cited above, may reasonably be defined as forward elevation less than 90°, external rotation less than 20°, and internal rotation to the gluteal region (“unable to tuck in shirt” in the Simple Shoulder Test), consistent with the range of motion Neer considered “unsatisfactory,” Thorsness and Romeo considered as an indication for arthroscopic release, Carofino et al considered “stiff,” and Franta et al reported as “unsatisfactory shoulder arthroplasties”³,¹³,¹⁴,¹⁵,¹⁷ (TABLE 36.1).

Identification of the etiology of stiffness following shoulder arthroplasty will both direct current treatment and, through better understanding of the causes of stiffness, prevent stiffness in subsequent cases. Analysis of shoulder stiffness following arthroplasty can be divided into preoperative, intraoperative, and postoperative factors.