OKOJ, Volume 9, No. 2

Orthopaedic Biomaterials: Part III. Polymers

Advances in biomaterials have been central to improvements in orthopaedic implants in all fields of orthopaedics. For the clinician, patient care decisions are most enhanced by key principles and facts, as opposed to technical details. In part III of this series, we review the basic principles of polymers, including common materials, commercial implant applications, and modern manufacturing processes. Emphasis is given to clinical relevance for patient care decisions.

    • Keywords:
    • polymer

    • copolymer

    • blend

    • composite

    • microstructure

    • physical properties

    • glass transition temperature

    • machining

    • molding

    • extrusion

    • self-reinforcing polymer

    • polyethylene

    • ultra-high-molecular weight polyethylene

    • UHMWPE

    • cross-linking

    • sterilization

    • tribology

    • wear

    • linear wear

    • volumetric wear

    • osteolysis

    • delamination

    • pitting

    • third-body wear

    • backside wear

    • polymethylmethacrylate

    • PMMA

    • polyester

    • polylactide

    • PLA

    • polyglycolide

    • PGA

    • poly-L-lactic acid

    • PLLA

    • poly-D-lactic acid

    • PDLA

    • PLAGA

    • polyetheretherketone

    • PEEK

    • polydioxanone

    • polypropylene

    • polyamide

    • polyethylene-terephthalate

    • PET

    • polyanhydrides

    • polyphosphazenes

    • Subspecialty:
    • Adult Reconstruction

    • Basic Science

HOT TOPIC: Computer-Assisted Navigation in Orthopaedic Oncology

Using both modern imaging techniques and computer precision, musculoskeletal surgeons are beginning to explore the benefits of computer navigation in oncologic surgery. Currently, computer navigation involves both software and hardware designed to assist the orthopaedic surgeon preoperatively, intraoperatively, and postoperatively. The technique predominantly uses image-based and imageless platforms for reference to the patient. Image-based referencing uses preoperative MRI and CT data for guidance during surgery, whereas imageless referencing allows the surgeon to use software data collected intraoperatively to recreate a virtual model of the surgical field as a map. The technology for computer navigation also allows, for example, the use of optical instrumentation for intraoperative tracking of the surgeon's movements and the entry of pertinent anatomic landmarks in real time, or for selection and intraoperative use of the appropriate instrumentation for resection in a particular case. By increasing precision in the operating room, use of computer navigation may lead to improved clinical and functional results for the patient population in orthopaedic oncology.

    • Keywords:
    • computer-assisted navigation

    • computer-assisted surgery

    • navigation guidance

    • computer navigation

    • CT-based navigation

    • imageless navigation

    • precision tumor resection

    • three-dimensional planning

    • orthopaedic oncology

    • tumor resection

    • real time feedback

    • Subspecialty:
    • Musculoskeletal Oncology

Massive Rotator Cuff Tears: Current Concepts

Massive rotator cuff tears often lead to considerable pain and disability and are difficult problems to treat. A wide variety of surgical and nonsurgical treatment options for massive tears are available, including closed-chain physiotherapy, primary cuff repair, tendon transfers, augmentation grafts, and even arthroplasty. Each of these can provide pain relief, improvement in function, and overall patient satisfaction when performed in the appropriate patient. Because massive rotator cuff tears are often associated with older patients who may have underlying medical comorbidities, patient factors must be taken into account when determining the best treatment plan.

    • Keywords:
    • rotator cuff tear

    • cuff tear

    • full-thickness rotator cuff tear

    • calcific tendinitis

    • adhesive capsulitis

    • glenohumeral arthritis

    • acromioclavicular arthritis

    • suprascapular neuropathy

    • brachial plexitis

    • cervical radiculopathy

    • drop-arm test

    • external rotation at side strength and lag

    • belly-press test

    • lift-off test

    • sacral lag sign

    • hornblowers sign

    • arthroscopic rotator cuff repair

    • tendon transfer

    • latissimus dorsi transfer

    • reverse total shoulder arthroplasty

    • Subspecialty:
    • Shoulder and Elbow

Locked Plating for Proximal Humerus Fractures

Proximal humerus fractures are common musculoskeletal injuries, accounting for 4% to 5% of all fractures in adults. Most proximal humerus fractures are undisplaced or minimally displaced, stable fractures that can be successfully treated nonsurgically. Displaced fractures of the proximal humerus, however, are much more complex and represent a treatment challenge for the orthopaedic surgeon. Although debate continues over the treatment of displaced proximal humerus fractures, locked plating systems have grown increasingly popular as an adjunct to surgical management. Techniques for locked plating of two-, three-, and four-part proximal humerus fractures, anterior fracture-dislocations, and posterior fracture-dislocations are described herein. Familiarity with locking plate-screw implant designs, potential iatrogenic and postoperative complications, and effective rehabilitation protocol is important in helping the patient with a displaced proximal humerus fracture to achieve a good surgical outcome.

    • Keywords:
    • proximal humerus fractures

    • displaced proximal humerus fractures

    • two-part proximal humerus fractures

    • three-part proximal humerus fractures

    • four-part proximal humerus fractures

    • anterior fracture-dislocations

    • posterior fracture-dislocations

    • locked plating

    • locking plates

    • Subspecialty:
    • Trauma