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Management of proximal humerus fractures with the Equinoxe[R] locking plate system.

Fractures of the proximal humerus comprise approximately 5% of all fractures with between 300,000 to 700,000 reported cases per year. (1-3) These fractures occur commonly as a result of a low energy fall in patients with poor bone quality. (1) Over 70% of proximal humerus injuries occur in patients 60 years and older, overwhelmingly in women over men, with a 3:1 predominance. (4) With our population rapidly aging, orthopaedic surgeons in the USA should anticipate a three-fold increase in proximal humerus fractures within the next 30 years. (4,5) Already, the rate of proximal humerus fracture operative treatment increased by 25.6% from 1999 to 2005. (6,7) These facts underscore the importance of care of proximal humerus fractures, as well as the method of fixation when operative treatment is selected. However, there is still no consensus in the literature concerning the optimal management of these injuries, due to high rates of complications, such as osteonecrosis (ON) and screw penetration and also due to the variety of implants and surgical techniques available that are utilized for fracture fixation. (7-10) Options for treatment include percutaneous pinning, intramedullary nailing, locking plates, hemiarthroplasty, or reverse total shoulder arthroplasty, each offering advantages and disadvantages. (8,11) Locking plates have been a significant improvement in proximal humerus fracture fixation, as they potentially maintain anatomical alignment and stable fixation, especially in osteoporotic bone. (8) While one study has analyzed one company's proximal humerus locking plate, the Proximal Humerus Internal Locking System (PHILOS), there have not been detailed examinations of other implant types. (12) In 2010, Exactech, Inc., (Gainesville, FL) released the Equinoxe[R] proximal humerus locking plate with several new improvements on existing locking plate designs. The purpose of this study is to present the patient outcomes and complication rates of 55 consecutive proximal humerus fractures treated with the Equinoxe[R] proximal humerus locking plate.


This retrospective study reports on the evaluation of patients who sustained a proximal humerus fractures and were treated by fellowship trained orthopaedic traumatologists at a single academic center between December 2010 and December 2014 using the Equinoxe[R] proximal humerus locking plate. The institution's Institutional Review Board approved the study. All patients who underwent open reduction and internal fixation (ORIF) with the Equinoxe[R] locking plate between December 2010 and December 2014 were identified. Exclusion criteria included lack of complete functional data or follow-up less than 6 months. Fractures were classified according to the Neer classification. (13) Surgical intervention was indicated for significantly displaced fractures and based upon the number of anatomic fragments. Surgeons experienced in the technique and implant performed all procedures. All surgeries were performed in the beach chair position. All patients were administered regional anesthesia, general anesthesia, or a combination of the both. The surgeries were performed via a deltopectoral or superolateral approach.

The Equinoxe[R] proximal humerus locking plate was developed to restore the anatomy of the native shoulder, incorporating contours that correspond to the lateral humerus to increase fit and stability. (14) The fracture plate system was introduced in the USA in 2010 and features a design that attempts to reduce humeral head collapse and improve outcomes for patients with suboptimal bone stock by maximizing contact area. Additional features include the ability to deploy bone filler after plate seating, multiple screw and blade configurations, and a design to allow suture placement after the plate is secured (Fig. 1).

Patients undergoing treatment with the Equinoxe[R] proximal humerus locking plate were followed at standard intervals using the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire to assess functional outcome and with physical examination and radiographic examination to determine clinical outcome or development of a complication at 3, 6, and 12 months after surgery and as available beyond 12 months. (15) The DASH results in a score between 0 to 100 where 0 = no disability and 100 = extreme disability. (16) Complications were also recorded, if present. Humeral head osteonecrosis (ON), surgical site infection, screw penetration, and heterotopic ossification limiting mobility were considered complications. Descriptive statistics were utilized to identify mean DASH scores, complication rates, and most prevalent complications among the data set. Student's t-test were utilized to determine if DASH scores were statistically significantly related to Neer classification or presence of complication.


A total of 55 consecutive patients underwent proximal humerus repair with the Equinoxe[R] locking plate during the study period. Five patients were excluded from the study due to inadequate follow-up, and one patient was excluded due to concomitant fractures that affected extremity function. The remaining 49 patients with 50 fractures had a mean follow-up of 16.8 months (range: 6 to 44 months). Of the 49 patients, 31 (63%) were female and 18 (37%) were male, with a mean age of 60.7 [+ or -] 14.5 years (range: 25.9 to 87.7 years), with no significant difference in mean age by gender. The mean age-adjusted Charlson Comorbidity Index (CCI) was 2.85 (range: 0 to 6). The fracture classifications were: 19 (38%) two-part fractures, 18 (36%) three-part fractures, and 13 (26%) four-part fractures. The overall complication rate was 10% (N = 5). The most common complication was ON (N = 3; 6.0%) followed by infection, heterotopic ossification, and screw penetration (N = 1; 2.0% each) (Fig. 2). Four patients required reoperation (8.0%). Two patients underwent removal of hardware with irrigation and debridement for infection, one patient underwent removal of hardware for ON and screw penetration, and one patient underwent arthroscopic release for adhesive capsulitis. All patients healed radiographically with the exception of one patient who developed ON and infection and underwent subsequent removal of hardware. At latest follow-up, mean active forward flexion for the cohort was 140.8[degrees] [+ or -] 30.1[degrees], mean passive forward flexion was 155.7[degrees] [+ or -] 25.2[degrees], and mean active external rotation was 50.1[degrees] [+ or -] 17.9[degrees]. For patients with postoperative complications, mean active forward flexion was 106.0[degrees] [+ or -] 23.0[degrees], mean passive forward flexion was 136.7[degrees] [+ or -] 23.1[degrees], and mean active external rotation was 34.2[degrees] [+ or -] 24.4. Active forward flexion and external rotation were statistically significantly different in the presence of a complication (p = 0.005 and p = 0.038, respectively). Mean DASH score for the cohort was 19.1 [+ or -] 20.9. Mean DASH score for patients who developed complications and or underwent reoperations was 34.2 [+ or -] 24.3 (Fig. 3).


We found favorable clinical and functional outcomes with use of the Equinoxe[R] locking plate, with a safety profile comparable to any other plating system available on the market. (10,12) The implant allowed for reliable fracture healing, early range of shoulder motion, and a low complication rate. The mean DASH score reported in this series corresponds to a high level of functionality in patients treated in this series.

Surgical fixation of proximal humerus fractures should offer the opportunity for anatomic restoration, with the potential to meet the patient's expectations of functionality and postoperative shoulder movement. All internal fixation techniques have strengths and weaknesses. Percutaneous pinning and nailing provide a minimally-invasive surgical method but offer less stability than other constructs, leading to high nonunion and malunion rates. (17) While percutaneous pinning may be the least invasive method of operative fixation and therefore provides a theoretically lower chance of osteonecrosis, it carries potential complications of pin migration and osteomyelitis. (6,18) Intramedullary nailing may be useful in osteoporotic bone but has shown to have inferior stability compared to plating and is associated with rotator cuff dysfunction. (18) Maier and coworkers (6) demonstrated that nailing may be utilized for three-part and four-part fractures with either metaphyseal comminution or diaphyseal fracture with only minimal tuberosity displacement. Non-locked plates for proximal humerus fractures have fallen out of favor, especially in poor bone due to screw pullout and implant failure. (5,8)

Locking plates are considered the gold-standard implant for ORIF of the proximal humerus, due to their strength and rotational stability. (2,19) One biomechanical study demonstrated that locking plates were less sensitive than other constructs to bone mineral density in the proximal humerus, making them a better choice for osteoporotic bone. The study also showed that, among intramedullary nail and plate constructs, locking plates offered the greatest stability, under both bending and torsional loading. (20) This combination of strength and stability reduces the risk of failure that accompanies many other implants. (2,20)

The DASH score is considered a reliable and accurate method of ascertaining functionality and disability in the upper extremity. (16) A 2012 study of the PHILOS plate reported a mean DASH score of 36. (12) In a review of all available proximal humerus locking plates currently in use, Sproul and colleagues (10) identified an average DASH for patients of 26.6. By comparison, the patients in the present study had a mean DASH score of 19.1, potentially achieving full functionality in many instances. According to de Kruijf and associates, (21) the highest functional outcome (DASH scores) for geriatric patients with proximal humerus fractures undergoing operative treatment was achieved with the use of a locking plate, followed by intramedullary nail, and hemiarthroplasty.

Proximal humerus fracture ORIF is not without its share of complications. Osteonecrosis is most prevalent among Neer three-part and four-part fractures, with findings of 25% to 30% in percutaneous pinning and 3.1% to 16.4% prevalence in locking plate cohorts. (4,10) ON can develop long after initial trauma and surgery, in some cases after 5 years. (10) Correspondingly, results of ON, such as pain, joint arthritis, and decreased functionality, can take years to manifest, although in such cases ON is not an implant-related complication but rather a result of the fracture itself. (10) Because locking plates do not rely on frictional forces, less soft tissue stripping is required for plate placement. This may be the explanation for lower ON rates seen with locked plates compared to historical series. Usually, intra-articular screw penetration occurs concomitantly with ON, as ON decreases bone quality and facilitates humeral head collapse leading to screw penetration. (5) The prevalence of intra-articular screw penetration ranges from 7.5% to 23%. (4,10) The complication rates with the Equinoxe[R] plates in our cohort are considerably lower than other locking plates series in the literature. (12) Our ON rate of 6% and screw pullout rate of 2.0% are markedly lower than rates for all locking plates and other methods of fracture repair. (4,10)

This study has some limitations. The cohort described in this study was treated by fellowship-trained traumatologists who had extensive knowledge of the Equinoxe[R] plate system and extensive surgical experience. It was a retrospective study without a control group. Many cases of ON can occur upwards of 5 years postoperatively. Since the implant has not been in clinical use for 5 years, we may see this reported rate increase with longer follow-up.


While locking plate fixation pitfalls are well documented, including high complication rates and loss of reduction, the Equinoxe[R] proximal humerus locking plate, as reported in this study, provides excellent short-term clinical results with a low complication rate. Proximal humerus fracture fixation is and will continue to be an important skill in any orthopaedic traumatologist's arsenal; additional and longer-term clinical follow-up is necessary to confirm these positive results.

Conflict of Interest Statement

Kari Broder, B.A., and Anthony Christiano, B.A., have no conflict of interest to report. Joseph D. Zuckerman, M.D., and Kenneth Egol, M.D., are consultants for Exactech, Inc. and receive royalties on products related to this article.


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Kari Broder, B.A., Anthony Christiano, B.A., Joseph D. Zuckerman, M.D., and Kenneth Egol, M.D., Department of Orthopaedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, New York, New York.

Correspondence: Kenneth Egol, M.D., Department of Orthopaedic Surgery, Hospital for Joint Diseases, NYU Langone Medical Center, 301 East 17th Street, New York, New York 10003; kenneth.

Caption: Figure 1 The Equinoxe[R] fracture locking plate with (top) and without (bottom) blade (Exactech, Inc., Gainesville, FL).

Caption: Figure 2 Complication rates for our cohort of Equinoxe[R] locking plates versus literature-reported rates for all locking plates. Rates for ON, screw penetration, and reoperation were calculated as the averages of ranges put forth by multiple sources. (4,10)

Figure 3 Functional healing as assessed by the DASH score for
the patients in our cohort with complications. A DASH score of
less than 15 corresponds to "no problem," a score between 15 to
60 "problem but working," and a score of more than 60 "unable
to work." (15)

Return of Function As Assessed by DASH Score

"no problem"             51%
"problem, but working"   37%
"unable to work"         12%

Note: Table made from pie chart.


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Author:Broder, Kari; Christiano, Anthony; Zuckerman, Joseph D.; Egol, Kenneth
Publication:Bulletin of the NYU Hospital for Joint Diseases
Article Type:Report
Date:Oct 1, 2015
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