Is there an advantage in partial humeral resurfacing hemicaps?

The hemicap was designed as a partial humeral head resurfacing that removes a minimal amount of bone. Here is the AP x-ray of the right shoulder of an active man taken two years ago.

He was treated with a hemicap at another institution. 

Because of pain and a sensation of crepitance, he presented to our service. Physical examination revealed a limited range of motion with a grinding that was palpable. His x-ray at presentation to us is shown below, demonstrating contact between the unresurfaced portion of the arthritic humeral head and the glenoid.

This finding was verified at surgery as shown below - note the prominent bone beneath the hemicap.

This was revised to a traditional hemiarthroplasty, which replaced the arthritic humeral joint surface with a smooth prosthetic humeral head secured by an impaction grafted stem in the medullary canal. No glenoid arthroplasty was required. The postoperative x-rays are shown below.

Immediately after surgery the shoulder demonstrated improved range of motion without crepitance.

Comment: A smaller implant is not necessarily more conservative. The structural properties of the metal hemicap are quite different from the neighboring bone. Incomplete resurfacing of the humeral articular surface risks contact between arthritic humeral bone and the glenoid.

===

Consultation for those who live a distance away from Seattle.

Click here to see the new Shoulder Arthritis Book

Click here to see the new Rotator Cuff Book

To see the topics covered in this Blog, click here

Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'

Partial humeral head resurfacing - Arthrosurface

Durability of partial humeral head resurfacing

The concept behind partial humeral head resurfacing arthroplasty is to use a tack-like device to manage a humeral head defect. These authors report on 39 shoulders with focal chondral defects of the humeral head treated with partial resurfacing arthroplasty. Almost all had had prior surgical procedures on the shoulder. Many had other pathologies in addition to the loss of cartilage. These individuals were young (45.6 years (range, 27-76 years)). 

Of these 39 shoulders only 25 showed functional improvement. Six patients required revision and another 4 were recommended to have revision.


While this procedure attempts to preserve as much of the native humeral head as possible, the problems are (1) it is uncommon to have to have only a small part of the articular surface affected by arthritis, (2) with segmental damage from avascular necrosis, the underlying bone is not normal and may compromise the quality of Arthrosurface fixation, and (3) the mechanical properties of the metal joint surface are in marked contrast to that of the surrounding articular cartilage.


===
To see the topics covered in this Blog, click here


Use the "Search" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'



See from which cities our patients come.




See the countries from which our readers come on this post.

humeral head resurfacing arthroplasty and humeral hemiarthroplasty in cadavers - JBJS Jan 2012

Hammond et al performed a seven cadaver study comparing humeral head resurfacing and hemiarthroplasty.

The authors disclose that this study was funded by a grant from Arthrosurface (which was the resurfacing prosthesis used in this study) and that one of the authors has a consultancy arrangement with Arthrex (which markets this prosthesis).

The model was of a normal shoulder, not of a shoulder with any of the types of conditions for which shoulder arthroplasty is performed. In contrast to the clinical situation where shoulder joint replacement is indicated, the glenoid anatomy was normal.

The resurfacing technique involved reaming away the surface of the normal humeral head around a guidewire and then placing a resurfacing cap over the guidewire. In this procedure the humeral head is not removed. When approaching a patient with shoulder arthritis, both sides of the joint (the humeral head and the glenoid) are almost always involved. Retaining the humeral head severely compromises access to the glenoid making the glenoid arthroplasty (which fails most often) even more difficult. When using a humeral hemiarthroplasty the humeral articular surface can be sized with respect to thickness and radius of curvature and positioned at the height, version, medial/lateral and anteroposterior configuration that best suits the kinematics of the shoulder after the arthritic glenoid has been managed by either a ream and run or a total shoulder arthroplasty.

The hemiarthroplasty technique involved removing the humeral head which, in a real patient, would be important for accessing the glenoid so that the glenoid arthroplasty could be optimized.

With in vitro testing in 20 different positions, the glenohumeral contact area (Table I), the mean contact pressure (Table II), and the peak contact pressure (Table III) were not significantly different among the three preparations (intact, resurfacing and hemiarthroplasty). The peak pressure was significantly elevated, compared with that in the intact condition, in five of the twenty positions following resurfacing and in two of the twenty positions following hemiarthroplasty.

The authors of this paper placed the apex of the humeral head significantly more superiorly following resurfacing than in the intact condition in two of the twenty positions. Using their technique, the apex of the humeral head was located significantly more superiorly following hemiarthroplasty than in the intact condition in all twenty positions. However, these authors did not use the many methods available for optimizing the position of the humeral head with respect to the reconstructed glenoid in the surgical management of glenohumeral arthritis, including adjusting the height, curvature, thickness, version, and eccentricity of the humeral head.

The authors' conclusions: "Resurfacing more closely restored the geometric center of the humeral head than hemiarthroplasty did, with less eccentric loading of the glenoid. Compared with hemiarthroplasty, humeral resurfacing may limit eccentric glenoid wear and permit better function because the glenohumeral joint biomechanics and the moment arms of the rotator cuff and the deltoid muscle are restored more closely to those of the intact condition" seem valid in a cadaver model of a normal shoulder. However the realities of the clinical management of the arthritic shoulder do not suggest that a resurfacing provides the necessary access to the glenoid, where the real challenges lie, nor the flexibility in humeral head reconstruction that are offered by a stemmed humeral component. 

--

If you have suggestions for topics you'd like us to address in this blog, please send an email to

shoulderarthritis@uw.edu.

Use the "Search the Blog" box to the right to find other topics of interest to you.

You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty,  and rotator cuff surgery.

See the countries from which our readers come on this post.