Original article 1 Radial head resection and hemi-interposition arthroplasty in patients with multiple hereditary exostoses: description of a new surgical technique Mark Flipsena, John S. Hama, Arnard L. van der Zwana and Konrad Maderb Multiple hereditary exostoses (MHE) are a rare disorder characterized by the growth of bony protrusions. Elbow involvement is found in a considerable number of patients and varies from the presence of a simple osteochondroma to severe forearm deformities and radial head dislocation. Patients encounter a variety of symptoms, for example, pain, functional impairment, and cosmetic concerns. Several types of surgical procedures, therefore, can be offered, ranging from excision of symptomatic osteochondromas to challenging reconstructions. In this paper, we will discuss the essential basics of visualizing, planning, and treatment options of forearm deformities in MHE. In more detail, we will describe our current surgical technique as a salvage procedure for Masada type II forearm deformities in patients Introduction Multiple hereditary exostoses (MHE) are a rare autosomal dominant disorder characterized by the presence of multiple bony protrusions with a cartilage cap (osteochondromas). Osteochondromas in MHE occur as a result of abnormal enchondral bone growth characterized by metaphyseal protrusions of cartilage-capped bone . These osteochondromas often result in pain, whereas the disorder might lead to skeletal deformities, functional impairment, and cosmetic complaints because of the resulting deformities . Forearm osteochondromas and/or deformities are reported to occur in 50–85% of patients with MHE [3–5], which is associated with greater loss of function than in any other part of the body . Osteochondromas in the forearm, as in other long bones, most often develop at the site of the growth plate that distributes most to the growth of the specific bone. In the forearm, therefore, the site of predilection is in the distal ulna and radius. Osteochondromas at this location may cause different symptoms including pain and limiting motion because of impingement against the opposite bone. In particular, osteochondromas might obstruct unrestricted forearm rotation. Concomitant deformities of the forearm are also often present and might contribute toward further complaints and limitations in daily living. In some cases, osteochondromas and the resulting deformities in the elbow joint eventually lead to Preliminary results have been presented internationally at the BLRS/BAPRAS Annual Meeting (2016, Liverpool, UK), the SICOT Orthopaedic World Congress (2016, Rome, Italy), and the DKOU Congress (2016, Berlin, Germany). 1060-152X Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved. with MHE. J Pediatr Orthop B 00:000–000 Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved. Journal of Pediatric Orthopaedics B 2017, 00:000–000 Keywords: elbow reconstruction, external elbow fixator, hemi-interposition, Masada classification, Masada type II, multiple hereditary exostoses, multiple osteochondromas, radial head resection a Department of Orthopaedics, OLVG, Amsterdam, The Netherlands and Department of Orthopaedic, Trauma, and Spine Surgery, Section Upper Extremity, Asklepios Klinik Altona, Hamburg, Germany b Correspondence to Konrad Mader, MD, PhD, Department of Orthopaedic, Trauma, and Spine Surgery, Section Upper Extremity, Asklepios Klinik Altona, 22763 Hamburg, Germany Tel: + 47 181 881 8239; e-mail: firstname.lastname@example.org radial head dislocation or subluxation, which can have an additional negative effect on elbow and forearm function. This combination of forearm deformity and radial head dislocation is referred to as a Masada type II deformity according to the classification system reported by Masada and colleagues. In Masada type I, a combination of ulnar shortening and bowing of the radius together with osteochondromas of the distal ulna is present. In Masada type III, a relative radial shortening because of osteochondromas at the distal radius is present. In contrast to Masada types I and III, the Masada type II deformities are further specified on the basis of the presence of proximal radial osteochondroma(s) in Masada type IIa or IIb. As a consequence of the radial head dislocation, the Masada type II deformities demand a different approach because of their complexity and their influence on the elbow. The Masada classification is addressed in more detail later on in this manuscript. So far, there is no consensus with respect to indications for surgery or optimal treatment regimens for forearm osteochondromas and the different types of deformities. Treatment protocols for visualizing, planning, and treatment for Masada type I deformities have been reported before by our study group . The aim of this manuscript is to describe in more detail our treatment protocol including a new surgical technique for Masada type II deformities in MHE patients. The reported surgical procedure has now been performed in 15 selected cases; the results of this series will be analyzed and published in a separate paper. DOI: 10.1097/BPB.0000000000000496 Copyright r 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. 2 Journal of Pediatric Orthopaedics B 2017, Vol 00 No 00 The (blinded for submission) multiple hereditary exostoses database The (blinded for submission) is attended as an expertise center for MHE . More than 600 patients with MHE have been entered until this moment into a prospective database for various studies, including a large series of 120 patients with forearm osteochondromas and deformities (140 forearms) who were surgically treated since 2002 by three senior orthopedic surgeons. Surgical procedures performed included excision of osteochondromas, gradual ulnar lengthening, and radial corrective osteotomy (proximal and distal). Also, a combination of these procedures was often performed for forearm deformities, usually corrective osteotomy of the radius and/or the ulna with plate fixation of the radius and monolateral lengthening fixators for the ulna using hydroxyapatite-coated fixator pins and a dedicated lengthening and aftercare protocol. In most cases, these extended reconstructive procedures were perfomed for Masada type I defomities. In selected cases, the combination of surgical interventions was applied as a form of leveling procedure of the forearm in case of a Masada type II deformity in an attempt to reduce the (sub)luxated radial head, as was reported by Masada et al. . Masada et al.  found improvements in range of motion and radiographic findings in type II deformities treated by excision of osteochondroma, ulnar lengthening, and radial correction osteotomy. In one case, radial head resection was performed and they concluded by recommending this procedure for type IIa deformities. For the type IIb deformities, excision of osteochondroma, ulnar lengthening, and radial correction osteotomy are recommended . In selected cases of radial head (sub)luxation, redirectional proximal osteotomy of the radius with or without the ulna was performed, similar to the procedure reported for neglected Monteggia fractures. However, in persisting or recurrent radial head dislocation, despite leveling or redirectional procedures, with complaints of pain and/ or severe functional impairment, a salvage procedure including excision of the radial head and neck with a hemi-interposition using a local tissue flap and lateral ulnar collateral ligament (LUCL) graft reconstruction was considered a feasible treatment option. To date, we have performed this procedure in 15 MHE patients with a Masada type II deformity. The main reason for the use of this salvage procedure and not another form of treatment in type II deformities was the problem that we encountered in all 15 patients, that is, the severe deformation of the radial head, resulting in an inadequate and failing radiocapitular articulation (Fig. 1). Because of chronic (sub)luxation, large cartilage defects not only of the radial head but often also of the capitulum had developed in all cases. Because of this detoriation, reduction of the radial head was considered undesirable. To the best of our knowledge, this procedure has not been described before Fig. 1 Severely deformed radial head with cartilage defects, shown after resection. in the treatment of MHE Masada type II deformity. For other cases, such as inflammatory and post-traumatic arthritis of the elbow, autograft and allograft interposition arthroplasty procedures have been reported in the literature with satisfactory results [9–11]. The group of attending orthopedic surgeons counseled all patients and retrieved informed consent after presenting a structured treatment plan. Important basics in multiple hereditary exostoses of the forearm Since 1989, following the publication from Osaka by Masada and colleagues, the Masada classification for MHE deformity at the forearm level is generally used [7,8]. The classification is based on the morphological characteristics of the deformity on plain radiographs (Fig. 2). Three types are identified: (1) Type I: The main osteochondroma formation is located in the distal portion of the ulna. The ulna is shortened and there is bowing of the radius. However, the radial head is not dislocated (this is, according to Masada, the most common type: 55–61% of cases). (2) Type II: In addition to ulnar shortening, the radial head is dislocated (22–33% of patients). Bowing of the radius is less pronounced than in type I; this could be an effect of the dislocation. In subtype IIA, the radial head is dislocated because of an additional Copyright r 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. Radial head resection in MHE Flipsen et al. 3 Fig. 2 The Masada classification is based on the morphological characteristics of the deformity on plain radiographs Modified from Masada et al. . Adaptations are themselves works protected by copyright. So in order to publish this adaptation, authorization must be obtained both from the owner of the copyright in the original work and from the owner of copyright in the translation or adaptation. osteochondroma at the proximal metaphysis of the radius. In subtype IIB, there is no osteochondroma located in this region, but there is at the distal ulna. Dislocation of the radial head in general leads to rotational impairment, in particular, of pronation. (3) Type III: The main osteochondroma formation is in the metaphysis of the distal radius, and there is relative shortening of the radius. According to Masada et al. , this classification is quite useful as it indicates both the severity of the forearm deformity and the functional disabilities. Forearm rotation is most severely impaired in type I, whereas elbow motion is normal. Type II shows restriction of both elbow movement and forearm rotation. Radial deviation of the wrist is severely restricted in both subtypes. Type III retains almost normal forearm and elbow movement, but ulnar deviation of the wrist is often restricted and painful. Preoperative imaging and evaluation Radiographs of the total forearm in full supination and pronation as well as a total lateral view are taken: this is considered necessary to (i) visualize the presence of symptomatic and/or function limiting osteochondromas as well as (ii) deformities in both forearm bones, (iii) for imaging all four joints [elbow, wrist, distal, and proximal radioulnar joints (PRUJs)], (iv) to determine the center of rotation and angulation in case osteotomies have to be planned, and (v) to locate the most appropriate site for ulnar lengthening. Posteroanterior or anteroposterior radiographs are obtained with the arm placed on the imaging plate with the shoulder at 90° of abduction and the elbow at 90° of flexion for as far this is tolerable with patients’ range of motion. The beam is orthogonally directed toward the forearm in a neutral position in the posteroanterior direction. Several angles and other variables can be measured on the radiographs and form the basis for follow-up of forearm deformities during growth or outcome after forearm reconstruction. The most important radiographic measurements are the radial articular angle and the carpal slip. At the elbow joint level, the length and grade of dislocation of the radial head and the amount of radial head deformation are recorded. In addition, the congruency of the humeroulnar joint is assessed. Furthermore, the direction of the dislocation of the radial head (anterior or posteroradial) is visualized on lateral radiographs. Computed tomography with 3D reconstruction images are generally used to further visualize the complex deformity at the elbow level for planning of the location of radial head resection and to counsel patient and relatives. Computed tomographic imaging can also provide more insight into the joint anatomy and may visualize (early) degenerative changes. MRI was performed in selected cases to assess the status of the cartilage of the radial head and capitulum, and the presence and structural integrity of the LUCL. For evaluation of outcome, we used a prospective standardized protocol; pain scores, patients’ and/or parents’ complaints, restriction in daily living, preoperative and postoperative function, both at the elbow and at the wrist level, as well as elbow-ulnar and radioulnar joint (in)stability were recorded. Patient-specific outcome measures were also obtainted, including DASH, PRWE, and RAND36 questionnares. Multiple hereditary exostoses study group protocol Indications for surgery All surgeries were performed simultaneously by two senior orthopedic surgeons (Initials blinded for submission). Indications for surgery included a Masada type II deformity with PRUJ instability, chronic or recurrent radial head dislocation, functional impairment, pain, and severe deformation of the radial head with or without degenerative changes of the radial head and capitulum leading to unfavorable circumstances for reduction of the Copyright r 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. 4 Journal of Pediatric Orthopaedics B 2017, Vol 00 No 00 radial head. Cosmetic issues as a sole factor were not accepted as an indication for surgery. Procedures performed included radial head resection, hemi-interposition using a local tissue flap, and LUCL ligament graft reconstruction (most often indicated), followed by the application of a hinged elbow external fixator for 6 weeks or a plaster cast to maintain the optimal and most stable position of the elbow joint and to protect the reconstructed ligament. Procedures were most often performed after previous distal forearms procedures including excision of osteochondroma(s), ulnar lengthening and/or radial correction osteotomy, or previous proximal correction osteotomy. The severity of the deformity was determined on the basis of a radiological assessment. Operative technique Surgical technique The operative protocol was standardized. After induction of general anesthesia, each patient was examined preoperatively for proximal radial and/or posterolateral instability. A sterile tourniquet was placed at the most proximal aspect of the arm. The patient remained supine on the operating table with the arm placed on a hand table. Before surgical exposure, the positions of the radial head, the humeroulnar joint line, and other anatomic landmarks were determined using fluoroscopy and drawn on the skin using a sterile marker pen including a possible extension of the surgical approach proximal to the dorsum of the distal triceps region for raising a possible portion of the triceps humeri. The resection of the radial head and capitullar interposition arthroplasty was performed through the central portion of the marked approach by a 10 cm modified Kocher incision (Fig. 3). The Kocher interval between the extensor carpi ulnaris tendon and the anconeus muscle is typically defined by a thin stripe of fat observed through the deep fascia. The deep fascia was identified and incised along the supracondylar ridge, moving distally between the anconeus muscle and the extensor carpi ulnaris muscle. The extensor carpi ulnaris was reflected anteriorly with the common extensor origin by using sharp dissection of the underlying lateral collateral ligament complex. The anconeus muscle was elevated posteriorly. The LUCL complex was visualized, and its integrity and capacity to stabilize against lateral and posterolateral forces were documented to determine whether a tendon graft was necessary in cases of insufficient stability or plain absence of the ligament complex was noted (Fig. 4). After incision of the elongated joint capsule, the radial head was fully exposed and the morphology of the head and neck, the deformity, and the cartilage status was documented by photography. In cases with gross alteration of both morphology and cartilage radial head, resection was performed at the level of the radial neck. After reducing the elbow in 110° of flexion using fluoroscopy in a true lateral plane, the resection level was marked with a chisel in the projection of the joint line of the PRUJ (Fig. 5). Resection was performed using an oscillating saw while protecting the surrounding soft tissues with Langenbeck retractors. To raise the interposition flap, the inner part of the elongated central joint capsule was dissected from the undersurface of the common extensor origin by blunt and sharp dissection to elevate a 4 × 6 cm proximally rooted soft tissue flap (Fig. 6). Up to six bone anchors (Mitek 3metric; DePuy Synthes, Oberdorf, Switzerland) were placed after predrilling anterior and posterior at the respective rim of the capitulum humeri and the interposition flap was sutured into the joint, creating a durable interposition membrane (Fig. 7). In cases with sufficient Fig. 3 Fig. 4 The proposed lateral skin incision (Kocher approach) is drawn using anatomic landmarks (radial head and lateral epicondyle). The lateral ulnar collateral ligament complex is visualized and its integrity and capacity to stabilize against lateral and posterolateral forces is documented to determine whether a tendon graft is necessary. a, radial head; b, lateral ulnar collateral ligament. Copyright r 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. Radial head resection in MHE Flipsen et al. 5 Fig. 5 After reducing the elbow in 110° of flexion using fluoroscopy in a true lateral plane, the resection level was marked with a chisel in projection of the joint line of the proximal radioulnar joint. Fig. 7 Up to six bone anchors (Mitek 3metric; DePuy Synthes, Switzerland) were placed after predrilling anterior and posterior at the respective rim of the capitulum humeri (a), and the interposition flap was sutured into the joint, creating a durable interposition membrane. Proximal radial osteotomy (b). Fig. 8 Fig. 6 To raise the interposition flap, the inner part of the elongated central joint capsule (a) was dissected from the undersurface of the common extensor origin by blunt and sharp dissection to elevate a 4 × 6 cm proximally rooted soft tissue flap. LUCL complex, the joint capsule and the common extensor origin were sutured using modified Mason Allen sutures. In cases of gross radial instability, a central triceps graft was elevated (after proximal extension of the incision) and a double-strand docking LUCL ligament graft reconstruction using the technique published by Jones et al.  was performed. The insertion site for the tendon graft was prepared by drilling two holes with a 4 mm burr in the ulna in a manner that preserved a 2 cm One hole was located near the tubercle on the supinator crest (a) and the other hole was drilled ∼ 2 cm proximal to the first hole near the base of the annular ligament (b). osseous bridge or two cork-screws (Arthrex GmbH, Munich, Germany) were inserted into this region. One hole was located near the tubercle on the supinator crest and the other hole was drilled ∼ 2 cm proximal to the first hole near the base of the annular ligament (Fig. 8). A curved awl was used to create an osseous tunnel between these two drill holes, taking care not to violate the bony bridge. The isometric point was determined and the entry site for the graft was created using a 4 mm burr on the humerus at this location, avoiding severing of possible open growth plates. The hole was drilled to a depth of ∼ 15 mm. A dental drill with a small bit was used to Copyright r 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. 6 Journal of Pediatric Orthopaedics B 2017, Vol 00 No 00 create two small 15 mm exit punctures, separated by 1 cm, to allow for suture passage from the primary humeral tunnel. A suture passer was used from each of the two exit punctures to pass a looped suture that was used for later graft passage. The triceps tendon graft was woven through the ulnar tunnel from an anterior-toposterior direction. The limb of the graft that was stitched in a Krackow manner was passed into the humeral tunnel by shuttling the nonabsorbable sutures in the graft along with the sutures stitched into the posteriorly reflected capsule through the most posterior humeral puncture holes. With the first limb of the graft docked adequately into the humerus, the elbow was placed in 30°–40° of flexion and forced pronation. While tension was maintained on the graft, the arm was cycled (flexion–extension) to eliminate creep within the graft. The final length of the graft was determined by placing the free limb of the graft next to the humeral tunnel and visually estimating the length of graft that was necessary to adequately tension it within the humeral tunnel. This ideal tension point on the graft was marked with a skin marker and a no. 1 braided nonabsorbable suture was stitched in a Krackow manner in the free graft limb. The excess graft was excised carefully above the stitch and the graft was docked securely in the humeral tunnel with the sutures from the graft and the anteriorly reflected capsule exiting the small humeral puncture holes. Final graft tensioning was performed with the elbow positioned in 30°–40° of flexion and forced pronation. When adequate tensioning was achieved, the four pairs of graft sutures were tied over the osseous bridge on the lateral epicondyle. The capsular sutures were tied first, followed by the graft sutures. Closure was performed by approximating the extensor carpi ulnaris and the anconeus muscles before final skin closure. In cases with gross intraoperative instability and triceps grafting, a pediatric or a standard elbow hinged fixator (Orthofix Srl, Bussolengo VR, Italy) was applied using a standard operative technique published in detail elsewhere [13–15]. Postoperative management Postoperatively, the arm was immobilized in a posterior splint in full pronation and 90° of flexion for ∼ 10–14 days. In cases where an elbow fixator was used, it was locked in 90° of flexion and the central unit of the fixator was opened after 10–14 days to enable early active motion. The initial phases of rehabilitation allowed ∼ 30° of extension and 90° of flexion. These parameters were increased gradually until full extension and flexion was achieved. Range-of-motion exercises involving the wrist and hand were allowed without limitations. Strengthening exercises were generally initiated at 8–10 weeks postoperatively and full return to activity was permitted at 4–6 months depending on the specific activity. The elbow fixator was removed at 6 weeks postoperatively as an outpatient procedure without anesthesia in adults or under general anesthesia in the operating room in children. Pin-site care was performed on a weekly basis using a noncolored mild disinfectant. Complications This procedure was performed in a total of 14 patients. The median age of the patients at surgery was 11.5 years (range: 6.1–24.8 years). In nine cases, a previous leveling procedure had been performed. In these cases, treatment Fig. 9 Postoperative radiography of the elbow at the final follow-up in anteroposterior (a) and lateral (b) views. Copyright r 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. Radial head resection in MHE Flipsen et al. 7 with the new surgical technique was performed at a median of 3.1 years (range: 0.6–6.5 years) after the initial leveling procedure. The median follow-up duration for the entire group was 4.8 years; of these, 10 cases achieved skeletal maturity. A postoperative elbow radiography at 53 months of follow-up is shown in Fig. 9. No major procedure-related complications were observed, especially no external fixator-related radial nerve injures or acute Essex Lopresti phenomenon. It is important to state that at longer follow-up, a chronic slow proximal migration of the radius (chronic Essex Lopresti phenomenon) might occur with pain and functional deficit at the wrist level and chronic valgus instability of the elbow with late ulnar neuropathy. Proximal migration of the radius in these series was observed in one case (n = 1, 7%) at a follow-up of 21 months. At the final follow-up (68 months) at the age of 12 years, proximal migration of the radius had further progressed with bowing of the radius, but without pain complaints or a decrease in range of motion. This phenomenon was not encountered in any of the other skeletally mature or immature patients. In another case, superficial pin-site infection developed (n = 1, 7%). This was treated successfully with pin care and oral antibiotics. Acknowledgements Conflicts of interest There are no conflicts of interest. References 1 2 3 4 5 6 7 8 9 On the basis of the observations during outpatient visits, the new surgical technique seems to yield satisfactory results in the postoperative pain score, range of motion, elbow stability, patient satisfaction, and quality of life. These outcomes will be analyzed in detail and prepared for publication soon. 10 Conclusion 13 In MHE patients with a Masada type II deformity of the forearm, radial head resection, hemi-interposition arthroplasty, radiohumeral ligament augmentation, and temporary stabilization with a hinged fixator can be used as a salvage procedure. It is an optimal option for chronic radial head dislocation at advanced stages with osteoarthritis in patients after leveling procedures of the forearm. 11 12 14 15 Solomon L. Hereditary multiple exostosis. Am J Hum Genet 1964; 16:351–363. Goud AL, de Lange J, Scholtes VA, Bulstra SK, Ham SJ. Pain, physical and social functioning, and quality of life in individuals with multiple hereditary exostoses in The Netherlands: a national cohort study. J Bone Joint Surg Am 2012; 94:1013–1020. Schmale GA, Conrad EU III, Raskind WH. The natural history of hereditary multiple exostoses. J Bone Joint Surg Am 1994; 76:986–992. Solomon L. 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J Bone Joint Surg Am 2006; 88-A:221–223. Copyright r 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.