The Outcome of Hook Plate for Lateral Third Clavicle Fractures

Objectives: The objective of this study was to assess the outcome of displaced lateral third clavicle fractures which were fixed using hook plates. Introduction: The lateral third clavicle fractures in adults are unstable fractures requiring operative treatment and are prone to non-union and delayed union. The clavicle hook plate is one of the many operating techniques that can achieve a high rate of union and relatively low rate of complications for this type of fracture, as evident from its extensive use in the last decade or so. Literature suggests good results with many studies reporting union rates of up to 100%. However, the technique is not without its fair share of controversies regarding complications like shoulder impingement, resulting in long term shoulder pain and subacromial osteolysis. We aim to assess the outcome of the patients treated with hook plate and determine whether this technique has good outcome. Methods: 22 patients, who were previously operated on at two health-care centres of Peshawar from April 2016 to March 2019 for displaced fractures of the lateral third of the clavicle by using hook plate technique, were assessed retrospectively from case records and radiographs and clinical examinations of patients, to determine their functional and radiological outcome. The follow-up duration ranged from six months to three years. Result: The average age was 31.6 years with range of 18 to 53 years. Among these 17 were males and 5 females. All the fractures united successfully making the union rate 100%. The implant was removed from 6 of the cases, with only 3 of them due to complications. One of them had a periprosthetic fracture while the other 2 experienced persistent pain and limitation of abduction. Only 37% of the patients had long-lasting pain and 16% complained of stiffness with all of them returning to their work/sports successfully. The functional outcome according to constant score was above 80 in 90% cases. Conclusion: Surgical fixation of lateral-third clavicle fractures with a hook plate is an effective technique resulting in excellent rate of union and relatively good functional outcome.


Introduction
Clavicle fractures account for around 2.6% of all fractures and are common in young and active individuals [1]. Majority of the clavicle fractures are due to mechanisms involving highspeed falls or those that involve violent collisions. Such mechanisms cause a direct blow to the shoulder. Lateral third fractures are the second most common clavicle fractures, mid-shaft fractures being the most common [1][2][3]. The lateral third clavicle fractures have been classified by Neer according to the ligamentous injury and degree of displacement. Type I is the least severe injury in which the coracoclavicular ligaments are intact. In type II the coracoclavicular ligaments detach from the medial fragment with only the trapezoidal ligament remaining attached. Type III is a distal clavicular fracture that extends into the Acromioclavicular joint [1,4].
While majority of the clavicle shaft fractures can be successfully treated conservatively [1,[5][6][7]. The displaced lateral third clavicle fractures have a significantly high non-union rate and can result in delayed union, as they are unstable fractures. Therefore, the treatment of these lateral third fractures is often operative [2,8]. There are many operating techniques to fix such fractures, including trans articular k-wires, tension band, coracoclavicular screw, recontoured locking plates and dacron band fixation, with all of them providing good results. The hook plate is one such technique that has been used extensively in the past few decades with excellent outcomes, achieving a high rate of union and relatively low rate of complications [4,9]. Literature suggests good results with many studies reporting union rates of up to 100% [3,4,[10][11][12][13][14][15]. However, the technique is not without its fair share of controversies regarding complications like shoulder impingement by the implant resulting in long term shoulder pain [11,16,17]. We aim to assess the outcome of the patients treated with hook plate and to determine whether this technique results in a successful treatment ( Figure 1).   The average age of the patients was 31.6 years with a range of 18 years to 53 years. There were 17 males and 5 female patients with 13 of them injuring their right shoulder while the left side was involved in 9 of the cases. The commonest cause of their injuries were motor vehicle accidents and falls from height or sports injuries. All the fractures united successfully. There was no infection in any case. The implant was removed from 6 of the cases. Only 3 of the cases had their implants removed due to complications, one due to a periprosthetic fracture while the other two dues to persistent pain after successful fracture healing. The remaining three implants were removed 15 months post-operatively without any complications. No patient had subacromial osteolysis. Persistent shoulder pain and limited range of motion (especially abduction), was the most common complaint by the patients who underwent hook plate fixation. The Constant Murley scoring system showed score of 90 and above in 4(18%) cases, 80-90 in 16(73%) cases, below 80 in two (9%) cases (Table 1).

Discussion
Most authors agree that lateral clavicle fractures which are displaced need surgical fixation. There are many methods available including Kirchner wire fixation, locking plate fixation and lately hook plate fixation [7,10,18,19]. The use of the hook plate for fixation of displaced lateral third clavicle fractures in our setup yielded arguably good results with acceptable and encouraging functional outcomes. A study by Mousa [19] from Egypt showed over 90% union rate and the outcome was graded excellent in both short term and long term follow ups.
Lee et al. [20] from South Korea showed 100% union rate but had shoulder stiffness in up to 22% of their patients with Neer Type II fractures. Overall results were satisfactory. Another study published in Pakistan journal of medical sciences also showed significantly better results in lateral third fractures treated with hook plates thank wires [21] (Figure 3). Although we instruct and refer our patients to the Physiotherapy department for proper and early post-operative rehabilitation, very few of them actually follow and complete the programme properly. This was probably one of the chief factors in preventing some of the patients from achieving a full range of motion at the shoulder joint. Adding substance to this argument was the fact that in those who actively followed the post-operative rehabilitation instructions, stiffness was not an issue. Two of the patients were professional Polo players and are currently pain free with healed fractures and are actively playing. Tiren et al. [5] showed 96% union rate and Constant Murley score of 97 in their patients with lateral third clavicle fractures. 32% of their patients had impingement symptoms while 22% developed osteolysis in subacromial region.
A significant limitation of the hook plate technique is that the implant has to be removed once the fracture has united. This could be a deciding factor for some surgeons and or patients against this technique, although in our setup, this was not an issue as the resulting benefits greatly outweighed this. Swamy [22] from India had also excellent union rate with 87 Constant score and had infection in one case. He recommends routine removal of plate after fracture healing to prevent complications. Our results were in line with those of other such studies carried out around the world with comparable outcomes and we found the hook plate fixation to be an excellent and satisfactory method for fixing fractures of the lateral third of the clavicle. There is some disagreement about the removal of plate after fracture unites, most authors recommend removal. Otherwise there is risk of fracture medial to the plate in sportsman with falls [5,14, ,22-25].

Conclusion
Hook plate fixation of lateral third clavicle fracture has excellent results in terms of union and functional outcome. It has short duration of surgery and low complications.