**5. Necessary equipment**

588 Recent Advances in Arthroplasty

5. *Emotional History*: patients with ongoing poorly controlled mental health issues are not optimal candidates for this procedure. If patients have symptoms and disability out of proportion to the clinical scenario, have fibromyalgia or a significant poorly defined myofascial component to their pain or if patients have fallen victim to the disease construct of their condition, they are not likely to fair well with the Ream and Run procedure. The optimal patient has demonstrated a balanced self-management approach to their condition, has continued to remain active and engaged despite their physical limitation, and has demonstrated the emotional capacity to deal with the pain and life-altering nature of their diagnosis. Self-assessment scores can sometimes provide a useful window on a patient's emotional state. For instance, those patients who circle "No" on all 12 questions of the Simple Shoulder Score have a self-perceived disability that likely supersedes their actual physical limitation and their outcome after the Ream and Run will be uncertain. If a patient enters a "12" on a 0-10 Visual Analog Pain Scale, one should be concerned about the potential success of the Ream and Run.

1. *Glenoid Erosion and Morphology*: the success of Ream and Run hinges on the ability of the surgeon to achieve a smooth concavity that is oriented perpendicular to the native glenoid centerline. Preservation of subchondral bone leads to more predictable outcomes. In cases with preoperative posterior glenoid erosion, double concavity and/or posterior humeral subluxation, careful preoperative templating must be performed based on CT imaging to determine whether corrective reaming will compromise the aforementioned goals. Moderate correction often results in medialization of the glenoid, which not only reduces the surface area of the concavity but also may penetrate into the cancellous bone of the glenoid vault. In such cases, placement of a prosthetic glenoid component is recommended as hemiarthroplasty alone may result in postoperative erosion into the softer bone with consequent persistent glenoid pain. Patients noted to have decentering of the humeral head with glenoid erosion must be counseled preoperatively about the possible need for standard total shoulder arthroplasty pending the appearance of the

2. *Soft-tissue balance*: because younger patients with glenohumeral arthritis may have a variety of different arthritis types including post-traumatic and post-capsulorraphy arthropathy, there may be alteration of the soft-tissue anatomy from prior anatomy altering surgery. This is particularly the case for patients who may have undergone a prior Bristow or Latarjet type coracoid transfer in whom there can be significant scarring in the subscapularis and conjoint tendon region. If surgical releases are not able to result in a balanced soft tissue envelope that permits a wide range of motion, persistent postoperative stiffness may result in obligate translations that cause recurrent eccentric glenoid wear. Thus, a careful understanding the patients pre-operative anatomy and prior

3. *Proximal humeral anatomy*: achieving an anatomical reconstruction of the proximal humerus is equally important to recentering the humeral head into a properly oriented and shaped concavity. A modern arthroplasty system that allows accurate and reliable reproduction of the native shoulder anatomy is essential and care must be taken to restore the proper relationships between the head, tuberosities and shaft in terms of the joint center of rotation and cuff insertion. A resurfacing cap may be used as an

surgical history is critical to forecasting the success of the Ream and Run.

**4.2 Anatomy factors** 

glenoid after corrective reaming.

In order to restore proper load bearing mechanics at the glenohumeral articulation, the reamed glenoid must be sufficiently concave to ensure stability, and sufficiently conforming to avoid load concentration over a small area. Thus, custom-made reamers are necessary so that there is a corresponding reamer for each humeral head diameter.(Figure 7) In order to avoid too much constraint and permit physiological glenohumeral translations, a 2mm mismatch between head diameter and reamer diameter has become the convention, as previously discussed. Thus, if the chosen head size is 52mm, a custom reamer with a diameter of curvature of 54mm is used for glenoid reaming. These reamers should enlarge in circumference as their diameter enlarges in order to contact the surface area of the native glenoid. Cannulated reamers are preferable in that they can follow a pre-drilled K-wire oriented along the glenoid centerline. This greatly improves the accuracy of the reaming process when correction is needed. An open blade reamer design is also beneficial since it allows the surgeon to see the area of bone that has been reamed during version correction.

Fig. 7. Custom reamers are necessary for the Ream and Run. They should have incremental increases in the diameter of curvature by 2mm and should increase in size to cover a larger area of the glenoid face as the diameter increases. Open blade reamers are helpful in following the degree of correction during the reaming process.

An arthroplasty system of the surgeon's choice can be used with the stipulation that the chosen system allows reliable and reproducible anatomical reconstruction of proximal humeral anatomy. The author currently uses the Synthes EPOCA shoulder system (Synthes,

Humeral Hemiarthroplasty with Spherical Glenoid

translation at the conclusion of the case.

Reaming: Theory and Technique of The Ream and Run Procedure 591

humeral retrotorsion is selected. In the author's personal series, circumferential capsular releases have never resulted in postoperative posterior instability but do improve range of motion during the early recovery. If there is a concern about posterior laxity, the rotator interval can be closed slightly more medially to provide a checkrein against posterior

The humeral osteotomy is then made along the anatomical neck generally in 25-30 degrees of retrotorsion. It is critical that this cut is flush with the articular-sided insertion of the supraspinatus tendon fibers so the anatomical reconstruction of the head-tuberosity relationship can be properly achieved.(Figure 8) Once the cut is made and refined, osteophytes around the margins of the anatomical neck can be removed, particularly those inferiorly which can cause calcar impingement with the inferior glenoid if not cleared out. A head diameter that best covers the osteotomy surface is then chosen. It is best to err toward the smaller size assuming there will be no uncovered bone that would impinge during glenohumeral rotation.

Fig. 8. The humeral osteotomy should be flush with the insertion of the supraspinatus tendon to restore the head-tuberosity relationship. The trial stem should be positioned to

the head can be reamed and the cap sized according to the system's technique.

scapular body, which is critical for restoring orientation of the glenoid concavity.

If a stemmed arthroplasty is to be used, the humeral canal can then be prepped via the conventions of the given system and a trial stem placed. If a cap prosthesis is chosen, then

The humerus is then subluxated posteriorly using a Fukuda or similar retractor. A complete circumferential release of the subscapularis can now safely be performed. The interval between the anterior capsule and inferior muscular fibers of the subscapularis is developed with Metzenbaum scissors allowing safe release of the anterior capsular from the glenoid rim and release of adhesions to the coracoid base. All adhesions should be released so that external rotation can be restored. The surgeon should feel a soft bounce when the subscapularis is pulled laterally. A blunt Hohman or spiked ribbon retractor can then be placed medially within the subscapularis fossa with the tendon and lesser tuberosity tucked medially behind it. This should allow full visualization down the anterior face of the

restore humeral retrotorsion of approximately 25-30 degrees.

Westchester, PA), which includes press-fit and cemented stem options and a dual eccentricity design that allows precise placement of the humeral head on the humeral osteotomy surface. This precision improves the accuracy of restoring the humeral center of rotation and head-tuberosity relationship, which is critical in defining soft-tissue balance and proper rotator cuff function.
