Summary The OsseoFit™ Stemless Shoulder System is indicated for anatomic total shoulder arthroplasty in patients where a bone-sparing, stemless solution is desired to maximize humeral fixation. It achieves this through OsseoTi® Porous Metal Technology and a site-specific fin design that creates a stable, biological press-fit while simplifying the surgical workflow with integrated suture holes. This system addresses a wide variety of patient anatomies using its versatile inlay and onlay size options. Indications Indications osteoarthritis indicated for anatomic total shoulder applications Contraindications local/systemic infection, sepsis, and osteomyelitis active local or systemic infection sepsis osteomyelitis inadequate humeral bone inadequate bone may lead to poor implant fixation large metaphyseal cysts may compromise stemless fixation irreparable cuff tear rotator cuff must be functionally reconstructable for anatomic total shoulder arthroplasty revision of any stemmed or stemless prothesis contraindicated for revision of any stemmed or stemless prosthesis Anatomy Osteology humeral head anatomic neck greater tuberosity lesser tuberosity bicipital groove metaphyseal cancellous bone Muscles deltoid forms the lateral border of the deltopectoral interval pectoralis major forms the medial border of the deltopectoral interval subscapularis released and repaired according to surgeon preference Ligaments glenohumeral capsule is released as needed to expose the humeral head and glenoid coracohumeral ligament contributes to rotator interval constraint superior, middle, and inferior glenohumeral ligaments contribute to anterior stability transverse humeral ligament overlies the bicipital groove Nerves axillary nerve courses inferior to the subscapularis and around the lateral humerus must be protected musculocutaneous nerve lies medial to the coracobrachialis and conjoint tendon suprascapular nerve is at risk with aggressive posterior-superior glenoid exposure Blood supply anterior and posterior humeral circumflex arteries arcuate artery is a terminal branch of the anterior humeral circumflex system suprascapular and circumflex scapular vessels Preoperative Planning X-rays A/P, scapular Y and axillary views evaluate bony anatomy, humeral head position, glenoid wear, deformity, and acquired bone loss use x-ray templates to estimate stemless humeral implant size assess whether an anatomic total shoulder reconstruction is appropriate CT assess bone quality and identify any humeral bone tissues use to assess bone quality and identify humeral bone issues that may affect implant selection evaluate metaphyseal bone stock, cysts, avascular necrosis, deformity, and cortical support Approach Extended deltopectoral anterior incision with an optional biceps tenodesis beginning immediately above the coracoid process and extending distally and laterally, following deltopectoral groove along the anterior border of the deltoid Technique Humeral head resection expose the humeral head and identify anatomic neck landmarks fixed-angle resection targets 135° inclination and 30° retroversion select left- or right-specific extramedullary resection guide align the guide post with the humeral shaft for fixed-angle resection align the 30° version rod with the forearm flexed at 90° place pins to define version and inclination and to stabilize the cutting surface resect the humeral head through the far side of the humeral head adjust the resection with the guide or calcar planer if needed assess bone quality with direct pressure perpendicular to the resected surface consider stemmed humeral fixation if cancellous bone is easily depressed or primary stability is questionable Humeral protection during glenoid preparation select the humeral resection cover that most closely fits the resected surface prepare the glenoid using the appropriate compatible glenoid technique remove the humeral resection cover before humeral sizing Humeral sizing place the humeral sizer onto the resection surface select the size intended to optimize cancellous bone fixation without violating the inner cortical rim orient the sizer so the bicipital groove bisects the superior and anterior fins insert the central Steinmann pin through the center of the sizer and through the lateral cortex avoid deep lateral cortical penetration to reduce risk to the axillary nerve place a lateral humeral retractor as needed to protect the axillary nerve confirm sizing after any additional planing Humeral bone preparation (boss reaming) ream until the boss reamer bottoms out on the resected surface ream over the central Steinmann pin with the boss reamer protect the lateral humerus and axillary nerve with a retractor remove the boss reamer while leaving the central Steinmann pin in place Humeral bone preparation (broaching) select the reference foot based on implant size select the broach that corresponds to the humeral sizer align the broach superior fin with the superior indicator line on the broach inserter slide the assembly over the central Steinmann pin until the broach contacts the resection surface remove the inserter-reference foot assembly and central Steinmann pin perform broach stability testing consider stemmed humeral fixation if the broach is unstable Humeral head trialing determine humeral head diameter and height using the humeral head sizing template or the resected humeral head seat the head trial assembly into the broach rotate the trial assembly with the hex driver to assess coverage of the resection surface confirm alignment with the anterior and posterior borders of the humeral resection increase offset if the head trial does not cover one side of the resection decrease offset if the head trial overhangs the resected bone reduce the joint and perform trial range of motion record the final offset letter or interval on the proximal humerus remove and disassemble the head trial assembly Implant insertion remove the broach with the slap hammer while maintaining an on-axis trajectory use the same reference foot size used for broach insertion select the implant size corresponding to the final broach and operative side slide the reference foot down until it uniformly contacts the resection surface confirm superior fin markings on reference foot, implant, and bone are aligned disengage the inserter-reference foot assembly with axial traction and slight rotational force as needed onlay implant center boss is slightly proud of the resection surface, with fin top surfaces flush inlay implant sits below the resection surface Humeral head implantation select the final humeral head implant matching the trial diameter and height use the offset letter or interval determined during trialing place the humeral head into the concave surface of the impactor base on a rigid sterile table impact the adapter into the humeral head with the disposable impactor using a mallet, strike the head impactor at least twice until the humeral head is flush with the resection visually confirm uniform seating consider implant subsidence and stemmed fixation if no pre-impaction gap is present Technical specifications Implant design anatomically shaped asymmetric anchor design designed to match natural asymmetric humeral anatomy designed to maximize cancellous bone fit and help avoid cortical impingement six-fin configuration with progressive tapered wedge design fins are designed for press-fit insertion each fin contains a fully porous window anterior suture holes are present for subscapularis repair Porous technology OsseoTi® Porous Metal Technology is used in the stemless implant porous architecture is designed to mimic human cancellous bone design incorporates a fully porous 3D printed OsseoTi® lattice within a titanium framework Technical specifications OsseoFit Onlay Anchor Implant Side Size Left 1, 2, 3, 4, 5 Right 1, 2, 3, 4, 5 OsseoFit Inlay Anchor Implant Side Size Left 1, 2, 3, 4, 5 Right 1, 2, 3, 4, 5 OsseoFit Humeral Head Adapter