A total of 140 patients from two prospective clinical trials were analyzed. Both trials evaluated the results of minimally invasive surgery (MIS)-plating in proximal humeral fractures. The procedures were performed from May 2008 to November 2011, and only patients with a displaced proximal humeral fracture were included [5, 6]. The fractures were diagnosed by plain radiographs in the a.p. and axial views and were then classified according to the Neer classification by the surgeon in the operating suite. A CT scan was not routinely performed.
Patients who met the following criteria were initially excluded: age younger than 18 years, multiple traumas, pathological fractures, combined fractures of the upper extremity, a duration between trauma and surgery of more than 10 days, preoperative nerve or vascular lesions that persisted after closed reduction, grade II and III open fractures, fractures combined with shoulder dislocations, and isolated fractures of the greater or lesser tuberosity.
Furthermore, patients who either submitted an incomplete questionnaire or who received primary or secondary joint replacement were excluded from the mid-term analysis.
Our trials were approved by the Marburg School of Medicine ethics committee (file numbers 142-69192 and 150/09). Informed consent was obtained prior to patient inclusion.
A total of 140 patients were included. The follow-up rate was 90 % after 6 weeks, 78 % after 6 months, and 62 % after 4.5 years.
Of the 140 included patients, 16 died during follow-up. One patient had a stroke that prohibited further evaluation of shoulder function, and nine patients received a secondary prosthesis and were excluded from the follow-up. Of the 114 remaining patients, 43 could not be contacted. A total of 71 patients completed the questionnaire administered at the 4.5-year follow-up (Fig. 1). The shortest follow-up was 34 months, and the longest was 72 months.
Data from each follow-up of 52 patients were used to analyze the time course of the selected outcome parameters.
To assess potential bias, we also evaluated the data of the 43 patients who were lost to follow-up.
The procedure was conducted as previously described:
An anterolateral 3 cm deltoid split with incision of the bursa subdeltoidea was performed.
The axillary nerve was identified by index finger palpation through the bursa subdeltoidea, and its course was marked on the skin (Fig. 2).
A potentially displaced greater tuberosity was fixed by a stay suture or cerclage.
The fracture was reduced by ligamentotaxis (downward traction of the arm) and/or direct manipulation with pushers or rasps through the deltoid split to manipulate important fragments that were not attached to tendons or ligaments. The manipulation of pulling the arm downward simultaneously enabled the anatomic reduction. Moreover, the setting allowed the direct visualization of the manipulation by the intensifier.
The fracture was temporarily fixed by a Kirschner wire that was drilled using an oblique technique from proximal lateral (through the tip of the greater tuberosity) into the medial part of the proximal humeral shaft.
The plate was inserted below the nerve and temporarily fixed to the humeral head and the shaft by K-wires through the jig.
A long five-hole plate was percutaneously fixed with three locking screws to the diaphysis through the jig after verification of the correct position in both directions turning the forearm from neutral to a 90° internal rotation. To prevent damage to the axillary nerve, only the distal three holes were used.
The three cannulated locking screws were placed over the K-wires into the humeral head.
A displaced greater tuberosity was fixed through the holes in the plate by fiber wire or cerclage [5].
The shoulder was immobilized for the first 2 days after surgery. Early passive and limited active motion of the shoulder was initiated. Regarding abduction, however, only assisted abduction up to 90° was allowed for the first 6 weeks after surgery.
The implant
The non-contact bridging plate (NCB-PH; Zimmer, Warsaw, IN, USA) is a polyaxial locking plate used for internal fixation of proximal humeral fractures. Using a less-invasive deltoid split approach, the plate and the shaft screws are inserted with an aiming device.
The head area consists of five holes. Additionally, there are two angular holes designated for wire cerclages and non-absorbable sutures that can be used for additional fixation of the greater tuberosity.
Previous research has shown that the biomechanical properties of the implant are feasible for daily clinical practice use. However, some authors cited the thickness of the implant as a disadvantage that could lead to secondary impingement. [4, 7]
Assessment of mid-term results
At all follow-ups, the Constant score, which was adapted according to gender and age as described by Katolik, and the activities of daily living (ADL) score were recorded [8]. At our first follow-up, the patients were also queried to obtain their ADL scores before their injuries. Pain and subjective shoulder function were evaluated by the visual analog scale (VAS) score at discharge, 6 weeks, 6 months, and a minimum of 2.5 years (median 51 months) postoperatively. Our patients chose values on graphic scales from 0 to 10 according to their personal perceptions of pain and shoulder function. On these scales, a low value represented a low degree of pain or poor shoulder function, whereas a high value indicated a high degree of pain or good shoulder function. Additionally, relevant complications with regard to axillary nerve function were recorded at all follow-up visits.
Statistics
Results were documented in a case report format and registered in a database. A baseline analysis was performed and figures were generated using IBM SPSS statistics 22 (Statistical Package for the Social Sciences, IBM Corporation, Armonk, NY, USA). After a baseline analysis, a bivariate analysis of the dichotomous and numeric parameters was performed using analysis of variance (ANOVA) and chi-square tests. Next, a secondary analysis of the repetitive measurements for all parameters was performed. For these calculations, only patients with a full dataset were included (n = 52). A p-value <0.05 was used as the cut-off value for significant differences.
We performed multivariate regression analyses for the Constant and ADL scores to control for confounding factors, including age, gender, and fracture complexity (2-part vs. 3- and 4-part fractures).