Locking Plate Fixation for Proximal Humerus Fractures: A Comparison With Other Fixation Techniques

Abstract

Various traditional surgical treatment methods for displaced proximal humerus fractures were compared with locking plates. Ninety-eight patients were reviewed and functional outcomes were obtained. After a mean 45-month follow-up, trends were noted toward better fracture reduction with locking plates and greater range of motion (ROM) with percutaneous pinning. Complications occurred in 22 patients, unrelated to treatment type. Method of fixation did not correlate with outcome scores, but functional ROM was associated with better American Shoulder and Elbow Surgeons (ASES) scores. Locking plates are comparable to traditional fixation methods. Functional ROM is associated with better outcome scores.

The majority of proximal humerus fractures are minimally displaced and can be successfully treated nonoperatively with early rehabilitation.^1,2 Early studies reported less satisfactory results for 3- and 4-part fractures treated by closed reduction, with only 10% of patients achieving satisfactory function.^3,4 Closed reductions of comminuted fractures are difficult to maintain. Three- and 4-part fractures in healthy, active patients are typically treated with surgery to optimize shoulder function.^3,5

Despite general agreement that complex fractures should be treated operatively, no consensus exists on the type of surgical technique. Closed reduction and percutaneous pinning,⁶ tension band wiring,⁷ intramedullary nailing,⁸ plate fixation,⁹ and hemiarthroplasty¹⁰ have demonstrated mixed results. Defining appropriate treatment protocols is complicated by poor reproducibility and reliability of the commonly used classification system devised by Neer.^11-13 The AO/Association for the Study of Internal Fixation (AO/ASIF) classification system also has been shown to be insufficiently reproducible.¹⁴ Additionally, the most commonly used measurements of shoulder function by Neer¹ and Constant and Murley¹⁵ have been shown to be unreliable.^16,17

Several new locked plate devices have been developed because research suggests plates with attached (locked) screws may provide improved fracture stability and healing.¹⁸ Locking the screw to the plate mechanically recreates a point of cortical bone contact,¹⁹ which may be useful in the poor cancellous bone of the proximal humerus. Locking plates also have a preconfigured shape and screw direction, which may reduce hardware complications. Early clinical results using the locking proximal humerus plates have been promising,^20,21 although no comparisons with other techniques have been published.

This retrospective review examines all proximal humerus fractures consecutively treated using the Locking Compression Plate Proximal Humerus Plate (Synthes, Inc, West Chester, Pennsylvania) at 1 institution during the first 18 months of use. Outcomes of these patients were compared to matched historical cohorts of patients with similar displaced proximal humerus fractures treated by the same surgeons with other techniques.

Materials and Methods

An institutional review board–approved retrospective review was performed of 98 patients with proximal humerus fractures treated surgically by 5 fellowship-trained traumatologists, 1 of whom is an author (H.A.V.), over a 10-year period at a tertiary referral level I trauma hospital. Patients were treated according to individual surgeon preference with surgical indications including irreducible fractures, persistent fracture displacement, open fractures, or multiple traumatic injuries. All open surgical procedures were performed through a deltopectoral approach.

Two independent examiners not involved in the patients’ care (D.M.F., A.A.) evaluated anteroposterior, scapular Y, and axillary plain radiographs of the shoulder obtained at the time of injury, postfixation, and at most recent follow-up to classify the fracture and measure the fracture displacement and head–neck angle. Computed tomography (CT) scans were not used. The proximal humerus fracture was classified by the Orthopaedic Trauma Association system.²² If the 2 observers did not agree on the classification, the radiograph was reevaluated and consensus on the classification was reached.

All patients had a 12-month minimum clinical follow-up, with a mean of 45 months. At the most recent follow-up, shoulder range of motion (ROM) was evaluated by the treating surgeon and recorded. Patients were evaluated in clinic or contacted by mail or telephone and asked to complete a Musculoskeletal Function Assessment score and an American Shoulder and Elbow Surgeons (ASES) score. The Musculoskeletal Function Assessment is a 100-item self-reported general disability questionnaire that has demonstrated reliability and validity in patients with a broad range of musculoskeletal disorders,²³ with lower scores indicating better outcomes. The ASES score is derived from the visual analog scale score for pain (50%) and a cumulative score for several upper extremity–related activities of daily living (50%).²⁴ Higher scores indicate better functional outcome. The ASES has demonstrated reliability, validity, and responsiveness for several shoulder conditions.²⁵ Both Musculoskeletal Function Assessment and ASES scores are affected by increasing patient age, and a 10-point difference in scores has been deemed clinically relevant.²⁶

For purposes of analysis, the historical control patients were separated into different groups treated by blade plates, closed reduction with percutaneous pinning, and other methods of internal fixation, including tension band wiring and non-fixed angle plate/screw constructs (Other). Patient demographics, radiographic parameters, ROM, clinical outcome scores, and surgical complications were compared between each of the historical treatment groups and the Locking Compression Plate treatment group. MicrOsiris (Schwenksville, Pennsylvania) statistical and data management software was used to analyze the data and perform post-hoc power and sample-size analyses. Student t test was used to compare means between 2 treatment groups. Analysis of variance was used to compare the means between multiple groups with P values reported for each test. A chi-square analysis was used to compare the nonparametric variables between groups. The 95% confidence interval with P<.05 was used to determine significant differences between groups.

Results

The total number of proximal humerus fractures treated at this level I trauma center during the entire collection period is unknown. As an estimate, during the final 2 years of the collection period 110 patients with proximal humerus fractures were treated, and 35% of the fractures were treated surgically. The remaining analysis evaluates only the patients who required surgical treatment by 5 fellowship-trained orthopedic traumatologists. Each surgeon surgically treats >10 proximal humerus fractures yearly and is familiar with each surgical technique. The Locking Compression Plate was not available as a treatment option in our institution until July 2003, but was used with increasing frequency thereafter as surgeons became more familiar with its use.

Of the 146 patients treated operatively for a proximal humerus fracture during the study period, 27 patients (18%) had incomplete records and/or inadequate clinical follow-up. These patients were no different demographically than those included in the study, with respect to age, gender, mechanism, and fracture classification (P>.5 in all cases). An additional 19 patients (13%) were treated with primary hemiarthroplasty for nonreconstructable fractures, but these patients were excluded due to the significantly different demographics of this group compared to the remaining groups (mean age, 65 years; low-energy fractures 68%; P<.1). During the study period, 2 patients treated with intramedullary nails were excluded from the analysis. The demographic characteristics of the remaining 98 patients are in Table 1. All patients were followed clinically for a minimum of 12 months, and mean follow-up at final examination was 45 months. Twenty patients were treated with a Locking Compression Plate, 21 with blade plates, 35 with closed reduction with percutaneous pinning, and 22 with other internal fixation methods. As described below, the patients in each treatment group were matched for age, gender, mechanism of injury, surgical timing, fracture/dislocations, and fracture classification.

Mean patient age was 52 years (range, 17-86 years) with a normal distribution and no significant difference in mean age between each treatment group. Injuries were classified as low-energy if they occurred during a fall from standing position. The remainder of the injuries were of higher-energy mechanisms: motor vehicle accident, motorcycle accident, fall from height, or gunshot wound. Although minor differences were noted between the mechanism of injury and the gender of each treatment group, with the data available these differences were not significant (P=.5). There were no differences among groups regarding surgical timing. The 7 patients with fracture dislocations were distributed among the treatment groups. The length of clinical follow-up was >12 months in all patients (range, 12-103 months). Mean follow-up was shorter in the Locking Compression Plate group, since we reviewed patients treated in the first 18 months of use of this device in our hospital. Notably, all of the Locking Compression Plate patients had healed fractures, and any complications in the Locking Compression Plate group had been addressed within the follow-up period.

Seventy-five of the 98 total patients (77%) had a complete set of radiographs at most recent follow-up. This group was not different in terms of clinical results or in terms of demographics vs patients with complete radiographs (P>.5 for age, gender, mechanism, fracture pattern, type of treatment). Two patients had signed out their radiographs, but clinical follow-up was available. Twenty-one other patients had incomplete or inadequate radiographs (missing ≥1 views, or of unacceptable quality to make measurements).

There were 39 type IIA fractures (2-part), 39 type IIB fractures (3-part), and 20 type IIC fractures (4-part). Three fractures were open, 2 in the blade plates group and 1 in the Other group. One fracture in each group required scheduled bone grafting to achieve fracture union. Neither developed an infection. The distribution of fractures in each treatment group was not significantly different (P=.4). The fracture displacement between the inferior edge of the head fragment and the adjacent medial edge of the shaft fragment was measured on the initial anteroposterior shoulder radiograph (Table 2). The initial head–shaft fracture displacement was 26 mm on average (range, 5-76 mm). Although a trend was noted for less initial fracture displacement in the Locking Compression Plate group as compared to other groups, with the numbers available this difference was not statistically significant. Initial attempts to measure the fracture angulation were abandoned due to variability in the radiographic technique, which has been previously noted to be a critical factor in the assessment of the humeral fracture angulation.²⁷

The final anteroposterior shoulder radiograph was used to measure the final displacement of the inferior edge of the humeral head from the medial humeral shaft and the head–neck angle as described by Keene.²⁸ The average measurement by the 2 independent examiners was used as the final value. The radiographic measurements are displayed in Table 2. No significant differences were noted in the initial fracture displacement or fracture reduction when stratified by Orthopaedic Trauma Association classification. A trend was noted toward better fracture alignment in the Locking Compression Plate group, with reduced fracture displacement (P=.10) and valgus head–neck angle (P=.07). Post-hoc power analysis demonstrated that with power set at 80% and α=0.05, each group would have required 31 patients to detect a 4-mm difference in the mean fracture displacement and a 10° difference in the mean head–neck angle.

Data for forward flexion, abduction, and external rotation were available for 57 of the 98 patients (58%). Internal rotation was reported too infrequently for meaningful analysis. Shoulder ROM by each treatment is listed in Table 3. Although ROM was clinically the best in the closed reduction with percutaneous pinning group, with the numbers available this did not reach statistical significance (P=.10). Post-hoc power analysis demonstrated that with power set at 80% and α=0.05, each group would have required 36 patients to detect a 15° difference in shoulder ROM in any direction.

An independent examiner (A.A.) located 61 of the 98 patients (62%) to complete ASES and Musculoskeletal Function Assessment outcomes scores. These data were obtained at a mean of 53 months follow-up (range, 13-148 months). The data are reported in Table 4, along with normative scores for a general population.^23,26 Patients with proximal humerus fractures performed significantly worse than normal uninjured controls (P<.05). The treatment method had no effect on mean ASES (P=.5) or Musculoskeletal Function Assessment (P=.2) scores with the numbers available. The study group does not represent isolated proximal humeral fractures, and many patients had comorbidities and injuries that may have affected their scores. The 31 patients with isolated proximal humerus fractures had a mean ASES score of 71.9 and Musculoskeletal Function Assessment score of 27.4. No difference was noted between this group and the 16 patients with both a proximal humerus fracture and another injured limb (mean ASES score, 75.2; mean Musculoskeletal Function Assessment score, 26.6).

Complications occurred in 22 of 98 patients (22%; Table 5). Several patients had >1 complication. Complete humeral head osteonecrosis developed in 3 patients, all in the Other treatment group. Two of these 3 patients were treated with revision to hemiarthroplasty. The third patient requested nonoperative symptomatic treatment. One additional patient in the Other group was revised to a hemiarthroplasty for a malunion. Two of 2 patients in the closed reduction with percutaneous pinning group required early revision fixation with fixed-angle blade plates for malunion. Four of 6 patients who had a fracture nonunion required bone grafting and revision internal fixation. One patient each in the blade plates group and the closed reduction with percutaneous pinning group were comfortable despite a nonunion and elected nonoperative treatment.

Four patients reported impingement symptoms and stiffness related to prominent hardware that required removal. Three patients (9%) in the closed reduction with percutaneous pinning group had superficial pin tract infections treated with oral antibiotics and early pin removal. No deep infections resulted. One patient in the Locking Compression Plate group had a deep infection that required implant removal, debridement, prolonged intravenous antibiotics, and revision internal fixation. Two patients in the Locking Compression Plate group developed post-traumatic arthrosis, 1 of whom required surgical debridement and plate removal.

Discussion

The literature describes many options for treatment of displaced proximal humerus fractures.^3-10 Treatment focuses on the displaced fracture fragments, since these may have limited vascularity and may benefit from reduction and fixation. Using the Neer classification, >85% of all proximal humerus fractures are 1-part fractures that should heal successfully after a brief period of sling immobilization followed by early physical therapy within 14 days of injury.^1,2 In our retrospective study, we focused on displaced or high-energy 2-, 3-, and 4-part fractures. All patients were treated surgically, and several techniques were successful in attaining fracture healing. The clinical results of these different methods were similar. Our results with each technique parallel the results reported by other authors.^3-10 Few of these reports, however, make a comparison between techniques.

Neer² originally experienced treatment failure with internal fixation in 11 of 30 three-part fractures, but was able to improve to 86% satisfactory results with a suture tension band technique. Stableforth⁴ reported 100% satisfactory results with a similar tension band technique that focused on the reduction of the greater tuberosity fragment. Flatow et al⁷ extended these results to treat greater tuberosity 2-part fractures successfully with tension band techniques as well. Although this has worked effectively in older patients, it may be less reliable in younger patients with complex high-energy fractures or multiple extremity injuries.

Jaberg et al⁶ reported 95% fracture union with closed reduction and percutaneous pinning, but noted 4 cases (7%) of pin tract infection. Neurovascular complications, articular penetration, and pin migration have also been noted.²⁹ We noted a 91% union rate with our patients treated with closed reduction with percutaneous pinning and only 3 (9%) pin tract infections. There were 3 cases of pin migration; however, no neurovascular complications resulted.

Kristiansen and Christensen³⁰ reported only 45% satisfactory results according to Neer criteria using an AO T plate for 3-part fractures. Paavolainen et al³¹ obtained 63% satisfactory results using the same technique by positioning the T plate more inferiorly on the greater tuberosity to avoid impingement on the acromion; however, they still encountered intra-articular screw placement. In a group of younger patients (20 to 40 years), Moda et al³² obtained 83% satisfactory results with meticulous placement of a T plate and screws but noted poor results in patients with severe rotator cuff damage. In an attempt to avoid hardware-related complications of the T plate, Esser⁹ used a cloverleaf plate and was able to obtain 92% satisfactory results with a contoured cloverleaf plate. Semitubular plates fashioned into a blade plate for improved fixation have also demonstrated good results with few hardware complications.^19,33

Early clinical results using the Locking Compression Plate Proximal Humerus Plate have been promising, though not without complications.^34-36 Björkenheim et al²¹ reported the results of 72 elderly patients (mean age, 67 years) with isolated proximal humerus fractures treated with the Locking Compression Plate. Thirty-six patients (50%) achieved a good or excellent Constant score at 1-year follow-up, with reduced scores in elderly patients and those with type C fractures. There were 3 cases of osteonecrosis and 2 nonunions, but 19 fractures (26%) developed varus malalignment. Initial varus malreduction has been noted to increase the risk of fracture fixation failure.^34,37 Fankhauser et al²⁰ noted loss of proximal screw fixation and varus malalignment in 10% of cases. They recommended augmenting the proximal fixation with sutures placed through the rotator cuff and attached to the Locking Compression Plate. In addition, they reported 2 cases of osteonecrosis and 1 case of plate failure in their 29 patients. Constant scores averaged 74.6 for all patients, again with reduced scores noted with type C fracture patterns. Despite the paucity of published results, surgeons have begun using locked plating for complex proximal humerus fractures based on the theoretical benefits of improved fracture stability and enhanced healing.

Our retrospective review examines proximal humerus fractures treated using the Locking Compression Plate. The outcomes of these patients were compared to historical cohorts of patients with similar complex proximal humerus fractures treated by the same surgeons using other surgical methods. The treatment cohorts were well matched (Tables 1, 2) for age, gender, mechanism of injury, delay from injury to surgery, number of fracture dislocations, fracture complexity by Orthopaedic Trauma Association classification, and preoperative fracture displacement. There were 4 to 7 complications in each treatment group (Table 5), but the type of complication varied, and not all patients required secondary surgery. No differences were noted among treatment groups in rates of complication or secondary procedures. The only patients requiring revision to hemiarthroplasty were in the Other group (P=.01).

Trends were noted toward improved fracture reduction (mean displacement, 2.5 mm; P=.1) and valgus head–neck alignment (mean, 142.1°; P=.07) in the Locking Compression Plate group (Table 2), which could be advantageous for fracture healing.^34,35 A larger study may demonstrate improved alignment with the Locking Compression Plate, especially compared to blade plates or other fixation techniques, since the postoperative displacement and head–neck angle mean differences were minor between these groups. The ROM in the Locking Compression Plate group (mean forward flexion, 123°; mean abduction, 114°; mean external rotation, 45°) was also similar to the other treatment groups. However, our data did not establish a relationship between better fracture alignment and ROM or functional outcome.

A trend was also seen toward better postoperative shoulder forward flexion (mean, 145°; P=.1) in the closed reduction with percutaneous pinning group (Table 3). This may be the result of limited surgical dissection and scarring associated with the closed reduction with percutaneous pinning technique. More comminuted fractures or dislocations may not be adequately treated with this method, and these more complex injuries may be inherently associated with more postoperative stiffness. Complete surgical exposure for the other techniques involves extensive dissection of the deltoid. Fortunately, in all treatment groups mean range of shoulder motion was functional, as defined by Matsen et al’s criteria.³⁸

One notable finding of this review was that nearly all patients had worse functional outcome scores (mean ASES score, 71.5; mean Musculoskeletal Function Assessment score, 31.0; P=.0001) compared to normal age-matched control patients (Table 6). Mean scores were nearly 20 points different on each scale. Even after eliminating the 22 patients with a postsurgical complication, the mean ASES score of 74 and mean Musculoskeletal Function Assessment score of 29 were not much better. Surgical treatment of complex proximal humerus fractures may improve the results and function compared to nonoperative treatment,³⁹ but the patients often do not return to normal function.

Factors that may play a role in worse outcomes were separately analyzed (Table 6). Although the cohorts were too small to obtain statistical significance at P<.05, we observed trends for worse ASES scores in patients older than 65 years or with a history of surgical complication. Surgical delay >5 days, Orthopaedic Trauma Association type C fracture, and poor postoperative ROM were associated with worse functional outcomes. Older patients have been previously noted to have worse outcome scores on both the ASES²⁶ and Musculoskeletal Function Assessment²³ scales. The effect of surgical timing may represent medical comorbidities that delayed surgery and thus independently portend a worse outcome. Others have noted that patients with type C fractures have worse Constant scores.²¹ Although the type C fractures had fracture reduction of the humeral head similar to type A fractures, the tuberosity fractures, fracture comminution, and associated soft tissue injury likely led to more pain and difficult rehabilitation. Those patients who achieved <100° of forward flexion or abduction had the strongest association with poor outcome scores. A surgical complication affected shoulder function as measured by the ASES score, but had minimal effect on the overall health function as measured by the Musculoskeletal Function Assessment score.

The postoperative ROM was statistically associated with an improved outcome score, which reflects the fact that improved ASES and Musculoskeletal Function Assessment scores require functional shoulder ROM. Although successful postoperative reduction and head–neck angle restoration were not associated with improved outcome scores, 80% of patients had surgical reductions within 1 cm and a head–neck angle >100°. This reduction functionally converts the fracture to a Neer 1-part fracture that can be treated with rehabilitation. Successful operative treatment may depend on the same variable that leads to successful nonoperative treatment of simple 1- and 2-part fractures: early physical therapy. Perhaps the best indication for surgical treatment is to maintain an adequate stable fracture reduction to proceed with early ROM.

This study has several limitations. Although a prospective comparative trial might better decide the best surgical technique for proximal humerus fractures, the current study is a retrospective review of multiple fracture types. After the introduction of the Locking Compression Plate, only 3 of 23 fractures were fixed at our institution with alternative methods. Several surgeons felt that the Locking Compression Plate provided more stable fixation for complex fracture patterns. We speculate that the use of the Locking Compression Plate may allow more aggressive postoperative physical therapy and rapid return to productive activity. Such speculation by the treating surgeons may have led to treatment of fractures with less preoperative fracture displacement in the Locking Compression Plate group than the other groups (Table 2). Our retrospective review was unable to address these questions. We observed fracture union with accurate alignment in 19 of 20 patients treated with the Locking Compression Plate, despite a short period of clinical follow-up of these patients. This group also had a low complication rate despite its use for high-energy fractures, dislocations, and complex fracture patterns that have historically been subject to high rates of osteonecrosis and may have previously been deemed nonreconstructable, necessitating hemiarthoplasty. The specific indications, limitations, and cost effectiveness of the Locking Compression Plate implant warrant further study. We favor it for most fractures in active patients with type B and C patterns that cannot be adequately stabilized by other means.

A second limitation is the size of the study. The cohorts were too small to achieve statistical differences in the fracture reduction, ROM, and outcomes of the treatment groups. Since the majority of proximal humeral fractures are treated nonoperatively, it is difficult to collect a large group of surgically treated patients. The scope of this review was fairly broad in an attempt to collect as many patients as possible. A multicenter trial may be required to collect enough patients requiring surgical treatment.

Although the radiographs were evaluated independently, the ROM data were collected through visual examination by the treating surgeon. Not only may there be an observer bias in this method, but visual examination has been demonstrated to be fairly unreliable.⁴⁰ Since minimal differences were found in the ROM of different treatment methods, this effect on the study is fairly small. Another limitation is the use of the ASES scoring system. Although the ASES has been validated as a reliable and responsive index for several shoulder conditions,⁴¹ it has not been specifically validated for a traumatic population. No scoring systems have been validated for proximal humeral fractures.^42,43 We use this scoring system because of its ease of use and self-reported nature.

These preliminary results suggest that the Locking Compression Plate Proximal Humerus Plate is a favorable treatment option for displaced, comminuted proximal humerus fractures sustained by both low- and high-energy mechanisms and that it compares favorably to other established techniques. The blade plates and closed reduction with percutaneous pinning groups also had few complications with similar postoperative fracture alignment. Several patients treated by other methods of plate and tension band wiring fixation required revision to hemiarthroplasty after developing fracture malalignment or complete humeral head osteonecrosis. Hemiarthroplasty remains a viable option for older patients with osteonecrosis and head splitting fractures. All treatment groups demonstrated similar ROM and functional ASES and Musculoskeletal Function Assessment scores at final clinical follow-up.

Conclusion

Treatment of displaced proximal humerus fractures using the Locking Compression Plate Proximal Humerus Plate offers several theoretical advantages over other treatment modalities. We retrospectively reviewed the results and outcomes after treatment with the Locking Compression Plate vs several other surgical options. Although they did not reach statistical significance, several trends were noted. Better alignment was noted in the Locking Compression Plate group. Several cases of malunion and/or nonunion were seen in the blade plates, closed reduction with percutaneous pinning, and Other groups, whereas there were no cases of malunion or nonunion in the Locking Compression Plate group. Revision of fixation was required more frequently in the blade plates (2/21) and closed reduction with percutaneous pinning (4/35) groups vs the Locking Compression Plate group (1/21). Superficial infection was most common in the closed reduction with percutaneous pinning group (9%), but the closed reduction with percutaneous pinning group had the best ROM.

Despite noted trends, no differences were detected among treatment groups with regard to functional outcomes. This may be at least partially attributable to small sample size in each treatment group. However, functional ROM was associated with better outcome scores. Across treatment groups, the majority of patients had worse outcome scores compared to normal, uninjured age-matched controls. Thus, while surgical treatment of proximal humerus fractures may be indicated in some cases, patients are not likely to return to their normal preinjury level of function. Additional comparative studies are warranted to further evaluate results, outcomes, and costs after treatment of proximal humerus fractures.

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Authors

Drs Friess, Attia, and Vallier are from MetroHealth Medical Center, Cleveland, Ohio.

Drs Friess, Attia, and Vallier have no relevant financial relationships to disclose. No funds were received in support of this study.

The authors thank Beth Ann Mahdinec for assistance with data collection and gratefully acknowledge members of the Department of Orthopedic Surgery at MetroHealth Medical Center—Brendan M. Patterson, MD; John K. Sontich, MD; John H. Wilber, MD; and Roger G. Wilber, MD—for inclusion of their patients in this study.

Correspondence should be addressed to: Heather A. Vallier, MD, Department of Orthopedic Surgery, 2500 MetroHealth Dr, Cleveland, OH 44109.