INDICATIONS

Osteolysis with or without associated fracture. This technique can be used in conjunction with strut grafting, particularly when fracture or bone distortion is present.

SURGICAL TECHNIQUE

The exposure is routine. As in all revisions, it is imperative that the ulnar and radial nerve be identified and protected.

Bone preparation follows the same basic steps:

FIGURE 66-2 The technique of impacting grafting. A, A smaller diameter tube is inserted through a larger diameter tube and extends past the larger diameter tube for a distance (D) by approximately 2 cortical diameters into the normal host bone. The outer diameter tube is inserted to the depth of the osteolytic segment. B, Small chips of cancellous bone are tightly impacted around the outer diameter tube. C, The cement cartridge is attached to the inner diameter tube, which is withdrawn to the level of the larger outer tube while cement is being injected. D, At this point, both tubes are withdrawn together while cement continues to be delivered through the inner tube. E, The implant is inserted through the cement and impacted graft composite and into normal host bone.

RESULTS

The value of impaction grafting was described originally for acetabular deficiencies by Schreurs et al.¹³ A 20-year experience with impaction grafting and cemented acetabular component revealed excellent long-term results as well as biopsy evidence of viability and incorporation of the impacted graft. This provides a rationale and a basis for the application at the elbow. We have recently reviewed our experience with 12 patients undergoing revision elbow arthroplasty using an impaction grafting technique between the years 1993 and 1997.⁹ The average surveillance period was 6 years, with a minimum 2-year follow-up. Recognizing that this represents a salvage-type revision, at the time of last follow-up, eight were intact after the index procedure (Fig. 66-3). In addition, two other patients underwent revision because of loosening and a third required revision due to a subsequent failure of the unrevised ulnar component. One patient developed an infection. Of the eight remaining patients, marked radiographic improvement was observed. At the final follow-up after the additional revision in three patients, five were excellent and four were good with three fair results. This suggests that impaction grafting is a viable option as a salvage for the difficult revision with poor bone quality due to osteolysis.

FIGURE 66-3 A, A patient with marked osteolysis of the distal humerus with gross loosening. B, Seven years following impaction, grafting shows a well-fixed implant with no evidence of loosening.

INDICATIONS

In type II or III periprosthetic fractures, bone struts are used to reconstruct distal or proximal bone deficiency and as bone graft to be placed behind the anterior flange.

SURGICAL TECHNIQUE

After the appropriate exposure, once again the nerves are identified. For the strut grafting of the humerus, it is particularly important to identify the radial nerve because wires are routinely passed under the nerve in order to provide fixation of this graft more proximally.

TECHNICAL NOTES

FIGURE 66-4 With osteoporotic bone, the bone strut is best applied as a pair to avoid wire cut through and to enhance stability. To avoid a stress riser effect, care is taken to avoid having the grafts end at the same level of the host bone

FIGURE 66-5 A, Deficiencies up to 8 cm in length can be addressed by a 4-cm extension of graft to span the anterior defect and by accepting a 2-cm shortening of the extremity. B, The distal 3 cm of the humerus is not required for proper position and fixation.

Pearl.

The cerclage wires are placed loosely around the humerus. The strut grafts are then fashioned and inserted anteriorly and posteriorly. The struts are stabilized by loosely tightening the cerclage wire.

7. The implant is then inserted into the cemented canal with premeasurement as to the appropriate depth of insertion, which dictates the distal extension of the anterior strut length.

Pearl.

The depth of insertion of the humerus is determined by the “Shuck” test. The trial implant is inserted and with the elbow at 90 degrees the ulna is separated as much as allowed by the soft tissue. This position determines the correct depth of insertion (Fig. 66-6).

8. The technique with the ulna is similar to that with the humerus. On occasion, a double strut construct is employed. One unique feature of ulnar strut grafting is that this can be used as an extension proximally to provide a lever arm against which the triceps may function more effectively.

FIGURE 66-6 The so-called “Shuck” test assists in determining the proper depth of insertion of the humeral component in the absence of distal humerus. The humeral implant is inserted down the canal and is coupled with the ulnar trial. At 90 degrees of flexion the forearm is then displaced distally. The position of the humeral component defines the optimum position for implant insertion

RESULTS

Some employ bone grafting techniques to reconstruct the distal condylar portion of the humerus, if this bone is required by the implant design.⁷ Experience using strut grafts at the elbow is relatively limited. The Mayo experience with these strut grafts for periprosthetic fractures of the humerus was reported by Sanchez-Sotelo in 2002.¹² Between 1991 and 1999 at the Mayo Clinic, 11 periprosthetic fractures with a loose humeral component were managed by two parallel strut grafts, as described earlier (see Fig. 66-4).

The average follow-up was 3 years but ranged from 0.75 years to 8 years. At the time of final assessment, there were no implant failures. Seven of eight patients with an intact reconstruction had a functional arc and no sign of pain (Fig. 66-7). One patient did have limited motion and moderate pain. The complications included one additional undisplaced humeral periprosthetic fracture that failed to heal with closed treatment, one olecranon fracture, one ulnar nerve palsy, and one case of triceps insufficiency. It was concluded that the use of a strut graft can be an effective means of reconstructing the patients with a type II or III periprosthetic fracture.

FIGURE 66-7 A, A Mayo type H2 periprosthetic fracture. Strut grafts applied to the distal humerus are secured with monofilament wire. The anterior strut is used to provide fixation for stability to the anterior flange of the implant. The posterior strut enhances the stability of the construct and avoids the wire from cutting through the osteoporotic bone. Anteroposterior (B) and lateral radiographs (C) at 1 year.

At the ulna, Kamineni et al⁸ documented the outcome of 22 patients so treated (Fig. 66-8). For the most part, these series represented a salvage procedure because they had an average of two and one-half prior procedures involving the elbow joint. Among 22 patients, the Mayo Elbow Performance score improved from 34 to 79 points. Overall some incorporation of the strut graft occurred in 91%, which reflects the approximate 90% satisfactory rate with the procedure.

FIGURE 66-8 A, Excessive ulnar deficiency. B, Problem was managed by dual onlay strut grafts. Note that the proximal extension of the ulnar strut provides a lever arm for the extensor mechanism in an attempt to enhance the extension moment.

INITIAL MAYO EXPERIENCE

Thirteen patients were reviewed who underwent allograft prosthetic composite.¹¹ With an average of 42 months’ follow-up, the Mayo Elbow Performance score was excellent for four, good for three, fair for one, and poor for five (Fig. 66-9). Nine of the 13 patients had minimal pain. The mean arc of flexion was 97 degrees. There were seven complications affecting seven elbows. Five of the seven, however, required revision procedures. Deep infection was the most serious complication, occurring in four elbows. There were two nonunions occurring at the allograft-humeral junction.

FIGURE 66-9 Traditional allograft prosthetic composite reconstruction. The proximal ulna is deficient (A) and resected (B). The junction of the allograft composite is secured with metallic plates (C and D).

As a result of this experience, we entered a period in which the allograft prosthetic composite was avoided in favor of the strut grafts described earlier. However, a modification of the fixation has provided a new perspective.

CURRENT MAYO TECHNIQUE

The difficulty and the time consumption of precise step-cuts prompted the concept of a “side-to-side” application. With this logic, the entire circumferential allograft is applied to the host bone and secured with cerclage wires. This approach has been used effectively in those individuals with marked bone loss and in whom the above-mentioned techniques would not be adequate (Fig. 66-10). Several variations have been developed (Fig. 66-11). One modification of this technique has been developed by employing the circumferential allograft to stabilize the implant, but the distal or proximal extension is modified as a continuation of a strut type graft (Fig. 66-12). There is some concern as to the strength of the interface between the allograft and the host bone but there is a high likelihood of healing of the strut graft. A third and final version of fixation is to telescope the circumferential allograft into the expanded host bone (Fig. 66-13).

FIGURE 66-10 A, An example of a side-to-side allograft prosthetic composite. Loss of the proximal one third of the ulna is treated with side-to-side application of fibular allograft (B and C). The broad surfaces of the allografts reliably heal to the broad surface of the host bone.

FIGURE 66-11 Several APC constructs are currently being employed. A, “Side-to-side” anastomosis in which the tubular allograft is secured to the tubular host bone by cerclage wires. B, A tubular allograft secures the implant, but the allograft is altered by removing a portion of the circumferential cortex, allowing a continuation of the remaining cortex to serve as a strut along the host bone. In many instances, a longer implant is employed so that it can traverse the circumferential allograft and then be inserted down the medullary canal of the host bone. C, In some instances, a ballooned cortex that is not felt to be adequate for impaction grafting is filled with circumferential allograft with the host bone securely wired to the allograft with anticipation that the host will heal to the allograft and the allograft will serve as secure stabilization of the cemented implant.

FIGURE 66-12 A and B, Patient with loss of distal humerus and proximal ulna. The problem was resolved with strut grafting on the humerus (C and D). A type II allograft prosthetic composite was employed in which the extended ulnar component traverses the circumferential allograft and then enters the host bone. The allograft continues distally as a strut (see Fig. 66-11B).

FIGURE 66-13 A, Patient with a loose ulnar component with osteolysis of the entire proximal ulna in a circumferential manner. B, This patient was managed effectively by cementing a long-stemmed implant into a circumferential fibular strut. The implant extends into the host bone. C, The circumferential fibular strut is wired to the proximal ulna with anticipation of osseous incorporation, providing and anticipating a long-term stable construct.

MAYO EXPERIENCE

We are currently investigating the outcome of these various modifications of the allograft prosthetic composite. Our impression to date is that this is a more reliable method to address these difficult salvage elbows. It is our clinical impression that the outcomes are better and the complication rate is lower with the approach described earlier.