Variable tilt angle taper lock shoulder prosthesis

Details Variable tilt angle taper lock shoulder prosthesis Variable tilt angle taper lock shoulder prosthesis

2001-09-13

2004-01-13

Shaver, Kevin (Department: 3732)

Prosthesis (i.e., artificial body members), parts thereof, or ai

Implantable prosthesis

Bone

Reexamination Certificate

active

06676705

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates generally to a a variable tilt angle shoulder prosthesis comprising a head component having a socket depression that will mate with a proximal hemispherical dome end of the humeral neck as a ball-in socket joint, such that said head is capable of rotating along any circumference of the proximal ball end end of the humeral neck imitate the natural radial tilt angle of a patient's humerus.
2. Description of the Related Art
The French surgeon Paean is considered to be the first surgeon to perform a shoulder replacement, when he implanted a rubber and platinum prosthesis in the shoulder of a 37-year-old baker with tuberculous arthritis in 1893. Paean was also credited with the first complication and revision when he removed the prosthesis 2 years later because of recurrent infection. In 1951, Neer introduced hemiarthroplasty as a treatment option for proximal humerus fractures and fracture dislocations. He soon expanded his indications to the treatment of glenohumeral arthritis. Cameron, B, 30(2) O
RTHOP
C
LIN
N
ORTH
A
M
305-309, 305-6 (1999). In 1974, Neer described the pathologic findings of glenohumeral arthritis and reported successful treatment with shoulder arthroplasty. In 1982, he reported on a series of patients with osteoarthritis treated successfully with total shoulder arthroplasty. Since then, shoulder arthroplasty has become the standard treatment for advanced osteoarthritis of the glenohumeral joint (Fenlin, J M and Frieman, 29(3) O
RTHOP
C
LIN
N
ORTH
A
M
423-34, 423 (1998)).
Constrained shoulder arthroplasty became popular in the 1970s to restore the stability that was presumably lost in the setting of rotator cuff insufficiency. These implants have largely been abandoned because of their limited success and high complication rate, including prosthetic and periprosthetic fracture of both the glenoid and the humerus. Neer performed his last fixed fulcrum arthroplasty in 1973, when he redesigned the humeral component so that it could articulate with a polyethylene glenoid component that conformed to the contour of the glenoid articular surface. (Cameron, Id., at 305-6.).
The indications for hemiarthroplasty broadened to include primary osteoarthritis, rheumatoid arthritis, rotator cuff arthropathy, and avascular necrosis. This technique offered surgeons a broader range of treatment options and heralded the resurgence of a new interest in the field. (Brown, T and Bigliani, L, 31(1) O
RTHOP
C
LIN
N
ORTH
A
M
77-90, 77 (2000)).
Most current implant systems are a variation of Neer's original design. Cameron, B, 30(2) O
RTHOP
C
LIN
N
ORTH
A
M
305-309, 305-6 (1999). The primary indication for total shoulder arthroplasty in osteoarthritis of the glenohumeral joint is severe, chronic, and progressive shoulder pain. Usually the pain is accompanied by decreased range of motion and compromised function. Surgery may be considered when symptoms become refractory to conservative treatment such as anti-inflammatory medication, rest, and physical therapy (Fenlin, J M and Frieman, 29(3) O
RTHOP
C
LIN
N
ORTH
A
M
423-34, 423 (1998)).
The human shoulder varies amongst patients in two important aspects: the tilt angle between the distal humerus and the proximal neck; and the radial offset. The radial offset is the rotation of the humeral head itself along the radius of the neck, and may be in any direction. Poorly fitting devices can result in complications including aseptic loosening, periprosthetic fracture, and anterior or posterior instability.
Humeral radial offset is related to subscapularis function and integrity. It has been recommended that re-establishment of the lateral humeral offset (the distance from the base of the coracoid process to the lateral-most point of the greater tuberosity) close to the anatomical position is important for biomechanical function. Overstuffing the joint with a thick metal-backed glenoid component or an excessively large humeral head implant may dramatically increase the lateral humeral offset, creating an internal rotation contracture and placing excessive stress on the subscapularis repair. (Cuomo, F., and Checroun, A., 29(3) O
RTHOP
C
LIN
N
ORTH
A
M
507-18
, AT
08-09 (1998)).
Artifact often makes visualization of soft tissue structures by magnetic resonance imaging suboptimal; however, it may occasionally enable the surgeon to assess the integrity of the rotator cuff tendon. This assessment is important, particularly when planning preoperatively for massive tears that might require tendon transfers or use of a tendon allograft. Computed tomography (CT) scans require special techniques to minimize artifact from the component but may be useful for evaluating bone stock, tuberosity fracture healing, or glenoid version and wear. If a rotator cuff tear is suspected, a routine arthrogram can prove to be invaluable for diagnosing full-thickness tears. Arthroscopy in this patient population may prove beneficial, although its indications for diagnosis and treatment require better definition. (Brown, T. and Bigliani, L, 31 (1) O
RTHOP
C
LIN
N
ORTH
A
M
77-90, 78-9 (2000)).
To insert a prosthetic device, the humeral medullary canal is reamed or broached (depending on the prosthetic design) by hand or power until minimal resistance is met. This is more of a sizing procedure than a reaming procedure. Most of the patients who undergo prosthetic replacement for osteoarthritis are also osteopenic, and it is very easy to split the proximal humerus by overzealous reaming or broaching.
Prostheses may be cemented into place, or press-fitted. Fenlin's preference is to use cement in all cases of osteoarthritis, with the exception of younger individuals with excellent bone quality, because the majority of cases with humeral side loosening are in uncemented cases. (Fenlin, J M and Frieman, 29(3) O
RTHOP
C
LIN
N
ORTH
A
M
423-34, 428 (1998)). Torchia reports that a shift in position of the humeral component occurred in 49% of the press-fit stems and none of the cemented stems in a series of 113 shoulder replacements between 1975 and 1981. (Torchia, M E, Cofield, R H, Settergren, C R, 6(6) J
SHOULDER
E
LBOW
S
URG
495-505 (1997)).
Shoulder replacement continues to share many of the numerous complications encountered with other major joint replacements, including instability, aseptic loosening, infection, periprosthetic fracture, deltoid dysfunction, rotator cuff tears, modular implant dissociation, neural injury, and heterotopic ossification. The incidence of such complications can be minimized by the surgeon's use of appropriate surgical indications, precise surgical and sterile technique, attention to detail, a tailored rehabilitation program, and a thorough understanding of shoulder anatomy and kinematics. (Brown, T and Bigliani, L, 31(1) O
RTHOP
C
LIN
N
ORTH
A
M
77-90, 77 (2000)).
Precise soft tissue balancing and proper prosthetic positioning are needed to restore both rotational and translational components of normal shoulder kinematics. Soft tissues must be perfectly balanced, symptomatic subluxation or dislocation may result. Posterior, anterior, and inferior stability must be evaluated and accurately determined during each procedure. With the trial components in place, stability is tested by employing several specific maneuvers. Posterior stability is assessed with the posterior drawer test and with flexion of the internally rotated arm. This arm position is required for many important activities of daily living. Anterior stability may be tested with an anterior drawer and by external rotation with the arm abducted and at the side. Inferior stability is evaluated by downward traction on the arm in neutral rotation. (Id., at 509.).
Complications associated with humeral head replacement have been of concern since the first shoulder arthroplasty was performed by Paean in 1893. Although this patient did reasonably well for 2 years, a resection arthroplasty was ultimately required because of a postoperative course complicated by a chronic

Affiliated with

Also associated with

Rating

Variable tilt angle taper lock shoulder prosthesis does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Variable tilt angle taper lock shoulder prosthesis, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Variable tilt angle taper lock shoulder prosthesis will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3239794