- Email: [email protected]
Clavicle hook plate fixation for displaced lateral-third clavicle fractures (Neer type II): a functional outcome study
J Shoulder Elbow Surg (2012) 21, 1045-1048
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Clavicle hook plate fixation for displaced lateral-third clavicle fractures (Neer type II): a functional outcome study Daniel W. Good, BA, MRCSI*, Darren F. Lui, MCh, MRCS, Michael Leonard, MCh, MRCS, Seamus Morris, MCh, FRCS (Trauma Orth), John P. McElwain, FRCS (Trauma Orth) Department of Trauma Orthopaedics, The Adelaide and Meath Hospital, Dublin, Incorporating the National Children’s Hospital, Dublin, Ireland Background: Controversy exists with the use of the acromioclavicular hook plate for the treatment of lateral-third clavicle fractures (Neer type II). This is thought to stem from problems associated with the hook plate causing impingement symptoms, which can cause long-term limitation of movement and pain. Our aim was to evaluate the functional outcomes of patients with lateral-third clavicle fractures treated with the hook plate. Methods: We prospectively reviewed all patients who underwent surgery from July 2005 to August 2009 using our prospectively recorded electronic patient information database. All patients were assessed in the clinic to determine both Oxford and Constant shoulder scores. Results: We identified 36 patients who underwent surgery with the hook plate, 26 men and 10 women. The mean age was 36.2 years (range, 22-60 years). Of the patients, 46% were smokers. The median length of hospital stay was 2 days (interquartile range [IQR], 1-3). The median follow-up was 28 months (IQR, 23-37). The median time from date of injury to surgery was 7 days (IQR, 4-76). The mean time to union was 3 months (IQR, 2-4), and the union rate was 95%. In total, 92% of plates were removed. The median time to removal was 4.5 months (IQR, 3-8.75). There were no complications. Two patients presented months later after falls with fractures around the medial end of the hook plate. Conclusion: Hook plates are an effective form of treatment for lateral third clavicle fractures. The best outcomes occur with plate removal before 6 months postoperatively, provided that the fracture has healed. Level of evidence: Level IV, Case Series, Treatment Study. Ó 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Hook plate; functional outcomes; lateral-third clavicle fractures; constant score
This study received institutional ethical board approval. *Reprint requests: Daniel W. Good, MB, BCh, BAO, BA, MRCSI, Department of Trauma Orthopaedics, The Adelaide and Meath Hospital, Dublin, Incorporating the National Children’s Hospital, Tallaght, Dublin 24, Ireland. E-mail address: [email protected] (D.W. Good).
There is equipoise for many surgeons with regard to the management of displaced lateral-third fractures of the clavicle (Neer type II) (Fig. 1). This stems from the fact that both conservative treatment and surgical treatment are associated with complications. Conservative management
1058-2746/$ - see front matter Ó 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2011.07.020
1046
D.W. Good et al.
Figure 1 Radiograph showing lateral-third displaced fracture of clavicle (Neer type II).
Figure 3
Radiograph after hook plate removal.
Materials and methods
Figure 2
Radiograph showing hook plate in situ.
of these fractures has been shown to be associated with relatively high rates of nonunion, delayed union, and malunion.14,15,19 It is also associated with acromioclavicular (AC) joint arthritis.19 Many surgeons would recommend surgical treatment for this fracture; however, there is no consensus as to the optimal method of fixation to use.7 Many published studies showing good outcomes are from small case series describing a new technique or using several different operative techniques from a single center over a long period of time with small patient numbers, and it is difficult to draw strong conclusions from these studies.10 A recent systematic review of 425 fractures found that conservative treatment resulted in a higher rate of nonunion (33.3%) compared with surgical treatment (22.2%) but yielded a lower rate of complications.15 This systematic review concluded that should surgical intervention be considered, it should be performed with intramedullary screw fixation, coracoclavicular stabilization, and interfragmentary fixation, because they have the lowest complication rates. Whereas the manufacturer of the hook plate (SynthesStratec Medical, Solothurn, Switzerland) recommends removal after union,18 there are reports of patients retaining the implant without any problems.8,13 The timing of removal of the implant has been controversial as a result. We report the use of the clavicle hook plate for the treatment of patients with displaced lateral-third clavicle fractures (Neer type II) presenting to our hospital over a 5-year period (Fig. 2). Our experience with the use of the hook plate for this fracture type contrasts with a recent meta-analysis,15 and we aim to show our results. We also aim to analyze whether there is a relationship between length of time that the implant is retained and decreased functional outcome.
We reviewed all patients with displaced lateral-third clavicle fractures treated surgically from July 2005 to August 2009. We retrospectively identified all patients who were treated surgically for any clavicle fracture and then sub-selected those with a displaced lateral-third (Neer type II) clavicle fracture. Patients were identified using our electronic patient information database. They were then prospectively reviewed in the outpatient department to determine functional outcomes at a median follow-up of 28 months after the date of surgery. Functional outcome was assessed with the new Oxford shoulder score4 and the Constant shoulder score, both of which have been widely used and validated to determine functional outcome in this setting.10,17 The Oxford shoulder score is particularly sensitive in revealing shoulder girdle problems.10 Outcome data included patient demographics, smoking status, union, time from injury to surgery, time from surgery to removal of plate, length of hospital stay, time to union, and any complications that occurred. Union of fractures was defined radiologically when 3 of 4 cortices were healed on 2 separate radiographs (Fig. 3). This was assessed prospectively and independently after review by 2 senior members of the orthopedic team. Union was accepted after independent agreement between the two. The operative technique was standardized among operating surgeons and is explained in detail elsewhere.3 Postoperatively, patients are managed by use of a shoulder sling for 1 week before starting early range of movement. They are advised against range of movement above 90 in flexion or abduction and to avoid sporting activity and heavy physical activity; this is in line with other institutions.2
Statistics After data collection, the data were entered into an Excel spreadsheet (Microsoft, Redmond, WA, USA), and we used paired t tests when comparing Oxford and Constant scores in different groups.
Results We identified 134 patients who had open reductione internal fixation (ORIF) of a clavicle fracture over the 5-year study period. Of these patients, 36 underwent ORIF for displaced lateral-third fractures of the clavicle (Neer type II). All 36 had ORIF with the clavicle hook plate. There were 26 men and 10 women, with a mean age of 36.2 years (range, 22-60 years); 46% were smokers. The
Hook plate for lateral-third clavicle fractures Table I
1047
Oxford and Constant shoulder scores based on timing of plate removal
Scoring system Oxford shoulder score Constant shoulder score
Mean (all patients)
Time to removal of plate
43.8 (38-48) 83.8 (44-100)
Statistical significance
<6 mo (n ¼ 26)
6 mo (n ¼ 6)
47.2 (45-48) 98 (88-100)
41.5 (38-48) 76.5 (64-100)
P ¼ .0178 P ¼ .0135
The median follow-up for all patients was 28 months (IQR, 23-37).
Table II
Oxford and Constant shoulder scores for plates with delayed removal and plates left in situ
Scoring system
Mean (all patients)
6 mo to plate removal (n ¼ 6)
Plate not yet removed (n ¼ 3)
Statistical significance
Oxford shoulder score Constant shoulder score
43.8 (38-48) 83.8 (44-100)
41.5 (38-48) 76.5 (64-100)
40 (38-42) 65.3 (44-80)
P ¼ .019 P ¼ .001
The median follow-up for all patients was 28 months (IQR, 23-37).
indications for ORIF were acute fractures in 80% (n ¼ 29) and delayed union in 20% (n ¼ 7). The median time from injury to surgery in the acute fracture group was 7 days (range, 4-76 days); that for the delayed-union group was 2 months (range, 1.75-3.5 months). We were able to prospectively review 35 of 36 patients in our outpatient department. We were unable to contact 1 patient. The median length of follow-up at the time of review was 28 months (interquartile range [IQR], 23-37). The rate of union was 95% (n ¼ 34). The median time to union was 3 months (IQR, 2-6). In total, at the time of review, 92% of plates (n ¼ 33) had been removed. The median time to removal of hook plates was 4.5 months (IQR, 3-8.75). Of the 3 patients in the study group with plates remaining in situ, 1 had nonunion and 2 had peri-implant fractures 1 and 2 months postoperatively after falling onto their affected shoulders and required further ORIF while maintaining the hook plates in situ, because their lateral-third clavicle fractures had not yet united at the time. The median length of hospital stay was 2 days (IQR, 1-3). The complication rate was 8.3% (n ¼ 3), with 1 superficial wound infection requiring oral antibiotics and 2 peri-implant fractures as described earlier, caused by falls onto the affected shoulder after discharge home. The Oxford and Constant shoulder scores are shown in Tables I and II. Statistically significantly better Oxford and Constant scores were obtained when the hook plate was removed compared with not being removed, and the best results were found with removal before 6 months.
Discussion A displaced lateral-third clavicle fracture presents a clinical dilemma for the orthopedic surgeon. This results from the lack of a clear gold standard treatment modality that has been shown to have the best outcome. Fractures of the
lateral third of the clavicle account for approximately 10% of all clavicle fractures.16 Many studies have shown poor outcomes with conservative treatment, with relatively high rates of nonunion and AC joint arthritis.14,15,19 Our results have shown a union rate of approximately 95% (n ¼ 34) despite almost half of patients being smokers, which has been shown to reduce bone healing and lengthen the time to bone union.1,11 The literature is quite consistent with regard to union rates of different methods of fixation, with many studies showing high union rates for K-wire fixation (95%),6 tension band wiring (90%),9 and Knowles pins (92%).20 However, complication rates have been high with these methods. K-wire fixation is controversial because of the high risk of K-wire migration.10,18 Knowles pins cross the AC joint and may cause osteoarthritis and pain in this joint; however, they tend not to migrate.7 However, many of these studies used mainly subjective outcome data and not validated shoulder scores. A recent meta-analysis also confirmed that internal fixation with the clavicle hook plate resulted in high rates of union.15 The mechanical strength around the AC joint has been shown to be weaker with the hook plate than with transarticular K-wires with a tension band wire.12 However, the mechanics of the hook plate are such that it has no rotational stiffness and allows normal rotation at the AC joint while allowing undisturbed bone healing at the fracture site.12 This mechanical advantage enables high rates of union and, more importantly, enables early range of motion, which may lead to better functional outcomes. The mean Oxford score for all patients was 43.8 (maximum score [indicating a normal shoulder], 48; minimum score [indicating a very poor shoulder], 0). There was a statistically significantly better Oxford shoulder score for those patients who had their hook plate removed before 6 months compared with the other 2 groups (removal after 6 months and plate in situ). The mean Constant score for all patients was 83.8 (maximum score [indicating a normal
1048 shoulder], 100). These results show that most patients obtain an excellent outcome. The best results (mean Constant score, 98) are achieved when the hook plate is removed before 6 months, which was done in the vast majority of patients (n ¼ 26). In 7 patients, there was a delay in plate removal. Of these 7 patients, 2 had a peri-implant fracture after discharge home and required a reoperation. There were 5 other delayed unions: 4 of these 5 eventually united, and the plates were removed after 7 months. Three patients have refused further surgery and have their hook plates in situ. A cadaveric morphometric assessment of the hook plate has been performed,5 which showed that there was a high rate of contact between the hook part of the hook plate and subacromial structures. Our subjective and objective functional outcome data have shown that hook plates are an effective treatment for a difficult fracture. There are excellent outcomes when the plates are removed before 6 months. Impingement symptoms can occur but tend to be confined to patients in whom there is prolonged retention of the hook plate or failure to remove the hook plate. It should be noted that postoperatively, our patients are instructed not to flex or abduct their shoulder above 90 ; this may prevent damage to subacromial structures that may occur because of contact with the hook part of the hook plate. Removing the hook plate is not universally regarded as essential, and there are reports of good outcomes without its removal.8,13 Our results have shown that functional outcomes are still good without removal of the hook plate; however, they show that after union, the earlier the plate is removed, the better the functional outcome. Because of difficulties with access to surgical beds for non-emergency surgery, in national health services, there can often be delays in plate removal.13 Our study shows that excellent outcomes are still obtainable with removal of the plate before 6 months.
Conclusion Our study shows that ORIF with the clavicle hook plate is a good option for a challenging fracture. We recommend removal of the hook plate within 6 months, because the Constant and Oxford scores are statistically significantly better. Hook plate fixation can be performed with minimal complications and union rates of up to 95%, despite almost half of the patients smoking.
Disclaimer The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
D.W. Good et al.
References 1. Castillo RC, Bosse MJ, MacKenzie EJ, Patterson BM, LEAP STUDY Group. Impact of smoking on fracture healing and risk of complications in limb-threatening open tibia fractures. J Orthop Trauma 2005; 19:151-7. 2. Charity RM, Haidar SG, Ghosh S, Tillu AB. Fixation failure of the clavicular hook plate: a report of three cases. J Orthop Surg (Hong Kong) 2006;14:333-5. 3. Clavicle hook plate technique guide. Solothurn, Switzerland: SynthesStratec Medical; 2003. Available from: URL: www.shoulderdoc.co.uk/ documents/synthes_clavicle_hook.pdf. Accessed January 4, 2011. 4. Dawson J, Rogers K, Fitzpatrick R, Carr A. The Oxford shoulder score revisited. Arch Orthop Trauma Surg 2009;129:119-23. doi:10.1007/ s00402-007-0549-7 5. El Maraghy AW, Devereaux MW, Ravichandiran K, Agur AM. Subacromial morphometric assessment of the clavicle hook plate. Injury 2010;41:613-9. doi:10.1016/j.injury.2009.12.012 6. Eskola A, Vainionpaa S, Paetiaelae H, Rokkanen P. Outcome of operative treatment in fresh lateral clavicular fracture. Ann Chir Gynaecol 1987;76:167-9. 7. Fann CY, Chiu FY, Chuang TY, Chen CM. Chen TH.Transacromial Knowles pin in the treatment of Neer type 2 distal clavicle fractures. A prospective evaluation of 32 cases. J Trauma 2004; 56:1102-5; discussion 1105-6. doi:10.1097/01.TA.0000082649. 57981.F9 8. Faraj AA, Ketzer B. The use of a hook-plate in the management of acromioclavicular injuries. Report of ten cases. Acta Orthop Belg 2001;67:448-51. 9. Flinkkil€a T, Ristinemi J, Hyvoenen P, Haemaelaeinen M. Surgical treatment of unstable fractures of the distal clavicle: a comparative study of Kirschner wire and clavicular hook plate fixation. Acta Orthop Scand 2002;73:50-3. 10. Flinkkil€a T, Ristiniemi J, Lakovaara M, Hyv€onen P, Leppilahti J. Hookplate fixation of unstable lateral clavicle fractures: a report on 63 patients. Acta Orthop 2006;77:644-9. doi:10.1080/17453670610012737 11. Hoogendoorn JM, Simmermacher RK, Schellekens PP, Van der Werken C. Adverse effects of smoking on healing of bones and soft tissues. Unfallchirurg 2002;105:76-81 (in German). 12. Keifer H, Claes I, Burri C, Holzworth J. The stabilizing effect of various implants on the torn acromioclavicular joint. A biomechanical study. Arch Orthop Trauma Surg 1986;106:42-6. 13. Meda PV, Machani B, Sinopidis C, Braithwaite I, Brownson P, Frostick SP. Clavicular hook plate for lateral end fractures: a prospective study. Injury 2006;37:277-83. doi:10.1016/j.injury.2005. 10.017 14. Neer CS II. Fracture of the distal clavicle with detachment of the coracoclavicular ligaments in adults. J Trauma 1963;3:99-100. 15. Oh JH, Kim SH, Lee JH, Shin SH, Gong HS. Treatment of distal clavicle fracture: a systematic review of treatment modalities in 425 fractures. Arch Orthop Trauma Surg 2011;131:525-33. doi:10.1007/ s00402-010-1196-y 16. Prost M. The shoulder, surgical and non-surgical management. Philadelphia: Lea & Febiger; 1978. 17. Renger RJ, Roukema GR, Reurings JC, Raams PM, Font J, Verleisdonk EJ. The clavicle hook plate for Neer type II lateral clavicle fractures. J Orthop Trauma 2009;23:570-4. doi:10.1097/BOT. 0b013e318193d878 18. Synthes-Stratec Medical. Manufacturer’s guide: clavicular hook plate. Solothurn, Switzerland: Synthes-Stratec Medical. October 2003. 19. Tambe AD, Motkur P, Qamar A, Drew S, Turner SM. Fractures of the distal third of the clavicle treated by hook plating. Int Orthop 2006;30: 7-10. doi:10.1007/s00264-005-0019-1 20. Wang SJ, Wong CS. Extra-articular Knowles pin fixation for unstable distal clavicle fractures. J Trauma 2008;64:1522-7. doi:10.1097/TA. 0b013e3180593646
www.elsevier.com/locate/ymse
Clavicle hook plate fixation for displaced lateral-third clavicle fractures (Neer type II): a functional outcome study Daniel W. Good, BA, MRCSI*, Darren F. Lui, MCh, MRCS, Michael Leonard, MCh, MRCS, Seamus Morris, MCh, FRCS (Trauma Orth), John P. McElwain, FRCS (Trauma Orth) Department of Trauma Orthopaedics, The Adelaide and Meath Hospital, Dublin, Incorporating the National Children’s Hospital, Dublin, Ireland Background: Controversy exists with the use of the acromioclavicular hook plate for the treatment of lateral-third clavicle fractures (Neer type II). This is thought to stem from problems associated with the hook plate causing impingement symptoms, which can cause long-term limitation of movement and pain. Our aim was to evaluate the functional outcomes of patients with lateral-third clavicle fractures treated with the hook plate. Methods: We prospectively reviewed all patients who underwent surgery from July 2005 to August 2009 using our prospectively recorded electronic patient information database. All patients were assessed in the clinic to determine both Oxford and Constant shoulder scores. Results: We identified 36 patients who underwent surgery with the hook plate, 26 men and 10 women. The mean age was 36.2 years (range, 22-60 years). Of the patients, 46% were smokers. The median length of hospital stay was 2 days (interquartile range [IQR], 1-3). The median follow-up was 28 months (IQR, 23-37). The median time from date of injury to surgery was 7 days (IQR, 4-76). The mean time to union was 3 months (IQR, 2-4), and the union rate was 95%. In total, 92% of plates were removed. The median time to removal was 4.5 months (IQR, 3-8.75). There were no complications. Two patients presented months later after falls with fractures around the medial end of the hook plate. Conclusion: Hook plates are an effective form of treatment for lateral third clavicle fractures. The best outcomes occur with plate removal before 6 months postoperatively, provided that the fracture has healed. Level of evidence: Level IV, Case Series, Treatment Study. Ó 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Hook plate; functional outcomes; lateral-third clavicle fractures; constant score
This study received institutional ethical board approval. *Reprint requests: Daniel W. Good, MB, BCh, BAO, BA, MRCSI, Department of Trauma Orthopaedics, The Adelaide and Meath Hospital, Dublin, Incorporating the National Children’s Hospital, Tallaght, Dublin 24, Ireland. E-mail address: [email protected] (D.W. Good).
There is equipoise for many surgeons with regard to the management of displaced lateral-third fractures of the clavicle (Neer type II) (Fig. 1). This stems from the fact that both conservative treatment and surgical treatment are associated with complications. Conservative management
1058-2746/$ - see front matter Ó 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2011.07.020
1046
D.W. Good et al.
Figure 1 Radiograph showing lateral-third displaced fracture of clavicle (Neer type II).
Figure 3
Radiograph after hook plate removal.
Materials and methods
Figure 2
Radiograph showing hook plate in situ.
of these fractures has been shown to be associated with relatively high rates of nonunion, delayed union, and malunion.14,15,19 It is also associated with acromioclavicular (AC) joint arthritis.19 Many surgeons would recommend surgical treatment for this fracture; however, there is no consensus as to the optimal method of fixation to use.7 Many published studies showing good outcomes are from small case series describing a new technique or using several different operative techniques from a single center over a long period of time with small patient numbers, and it is difficult to draw strong conclusions from these studies.10 A recent systematic review of 425 fractures found that conservative treatment resulted in a higher rate of nonunion (33.3%) compared with surgical treatment (22.2%) but yielded a lower rate of complications.15 This systematic review concluded that should surgical intervention be considered, it should be performed with intramedullary screw fixation, coracoclavicular stabilization, and interfragmentary fixation, because they have the lowest complication rates. Whereas the manufacturer of the hook plate (SynthesStratec Medical, Solothurn, Switzerland) recommends removal after union,18 there are reports of patients retaining the implant without any problems.8,13 The timing of removal of the implant has been controversial as a result. We report the use of the clavicle hook plate for the treatment of patients with displaced lateral-third clavicle fractures (Neer type II) presenting to our hospital over a 5-year period (Fig. 2). Our experience with the use of the hook plate for this fracture type contrasts with a recent meta-analysis,15 and we aim to show our results. We also aim to analyze whether there is a relationship between length of time that the implant is retained and decreased functional outcome.
We reviewed all patients with displaced lateral-third clavicle fractures treated surgically from July 2005 to August 2009. We retrospectively identified all patients who were treated surgically for any clavicle fracture and then sub-selected those with a displaced lateral-third (Neer type II) clavicle fracture. Patients were identified using our electronic patient information database. They were then prospectively reviewed in the outpatient department to determine functional outcomes at a median follow-up of 28 months after the date of surgery. Functional outcome was assessed with the new Oxford shoulder score4 and the Constant shoulder score, both of which have been widely used and validated to determine functional outcome in this setting.10,17 The Oxford shoulder score is particularly sensitive in revealing shoulder girdle problems.10 Outcome data included patient demographics, smoking status, union, time from injury to surgery, time from surgery to removal of plate, length of hospital stay, time to union, and any complications that occurred. Union of fractures was defined radiologically when 3 of 4 cortices were healed on 2 separate radiographs (Fig. 3). This was assessed prospectively and independently after review by 2 senior members of the orthopedic team. Union was accepted after independent agreement between the two. The operative technique was standardized among operating surgeons and is explained in detail elsewhere.3 Postoperatively, patients are managed by use of a shoulder sling for 1 week before starting early range of movement. They are advised against range of movement above 90 in flexion or abduction and to avoid sporting activity and heavy physical activity; this is in line with other institutions.2
Statistics After data collection, the data were entered into an Excel spreadsheet (Microsoft, Redmond, WA, USA), and we used paired t tests when comparing Oxford and Constant scores in different groups.
Results We identified 134 patients who had open reductione internal fixation (ORIF) of a clavicle fracture over the 5-year study period. Of these patients, 36 underwent ORIF for displaced lateral-third fractures of the clavicle (Neer type II). All 36 had ORIF with the clavicle hook plate. There were 26 men and 10 women, with a mean age of 36.2 years (range, 22-60 years); 46% were smokers. The
Hook plate for lateral-third clavicle fractures Table I
1047
Oxford and Constant shoulder scores based on timing of plate removal
Scoring system Oxford shoulder score Constant shoulder score
Mean (all patients)
Time to removal of plate
43.8 (38-48) 83.8 (44-100)
Statistical significance
<6 mo (n ¼ 26)
6 mo (n ¼ 6)
47.2 (45-48) 98 (88-100)
41.5 (38-48) 76.5 (64-100)
P ¼ .0178 P ¼ .0135
The median follow-up for all patients was 28 months (IQR, 23-37).
Table II
Oxford and Constant shoulder scores for plates with delayed removal and plates left in situ
Scoring system
Mean (all patients)
6 mo to plate removal (n ¼ 6)
Plate not yet removed (n ¼ 3)
Statistical significance
Oxford shoulder score Constant shoulder score
43.8 (38-48) 83.8 (44-100)
41.5 (38-48) 76.5 (64-100)
40 (38-42) 65.3 (44-80)
P ¼ .019 P ¼ .001
The median follow-up for all patients was 28 months (IQR, 23-37).
indications for ORIF were acute fractures in 80% (n ¼ 29) and delayed union in 20% (n ¼ 7). The median time from injury to surgery in the acute fracture group was 7 days (range, 4-76 days); that for the delayed-union group was 2 months (range, 1.75-3.5 months). We were able to prospectively review 35 of 36 patients in our outpatient department. We were unable to contact 1 patient. The median length of follow-up at the time of review was 28 months (interquartile range [IQR], 23-37). The rate of union was 95% (n ¼ 34). The median time to union was 3 months (IQR, 2-6). In total, at the time of review, 92% of plates (n ¼ 33) had been removed. The median time to removal of hook plates was 4.5 months (IQR, 3-8.75). Of the 3 patients in the study group with plates remaining in situ, 1 had nonunion and 2 had peri-implant fractures 1 and 2 months postoperatively after falling onto their affected shoulders and required further ORIF while maintaining the hook plates in situ, because their lateral-third clavicle fractures had not yet united at the time. The median length of hospital stay was 2 days (IQR, 1-3). The complication rate was 8.3% (n ¼ 3), with 1 superficial wound infection requiring oral antibiotics and 2 peri-implant fractures as described earlier, caused by falls onto the affected shoulder after discharge home. The Oxford and Constant shoulder scores are shown in Tables I and II. Statistically significantly better Oxford and Constant scores were obtained when the hook plate was removed compared with not being removed, and the best results were found with removal before 6 months.
Discussion A displaced lateral-third clavicle fracture presents a clinical dilemma for the orthopedic surgeon. This results from the lack of a clear gold standard treatment modality that has been shown to have the best outcome. Fractures of the
lateral third of the clavicle account for approximately 10% of all clavicle fractures.16 Many studies have shown poor outcomes with conservative treatment, with relatively high rates of nonunion and AC joint arthritis.14,15,19 Our results have shown a union rate of approximately 95% (n ¼ 34) despite almost half of patients being smokers, which has been shown to reduce bone healing and lengthen the time to bone union.1,11 The literature is quite consistent with regard to union rates of different methods of fixation, with many studies showing high union rates for K-wire fixation (95%),6 tension band wiring (90%),9 and Knowles pins (92%).20 However, complication rates have been high with these methods. K-wire fixation is controversial because of the high risk of K-wire migration.10,18 Knowles pins cross the AC joint and may cause osteoarthritis and pain in this joint; however, they tend not to migrate.7 However, many of these studies used mainly subjective outcome data and not validated shoulder scores. A recent meta-analysis also confirmed that internal fixation with the clavicle hook plate resulted in high rates of union.15 The mechanical strength around the AC joint has been shown to be weaker with the hook plate than with transarticular K-wires with a tension band wire.12 However, the mechanics of the hook plate are such that it has no rotational stiffness and allows normal rotation at the AC joint while allowing undisturbed bone healing at the fracture site.12 This mechanical advantage enables high rates of union and, more importantly, enables early range of motion, which may lead to better functional outcomes. The mean Oxford score for all patients was 43.8 (maximum score [indicating a normal shoulder], 48; minimum score [indicating a very poor shoulder], 0). There was a statistically significantly better Oxford shoulder score for those patients who had their hook plate removed before 6 months compared with the other 2 groups (removal after 6 months and plate in situ). The mean Constant score for all patients was 83.8 (maximum score [indicating a normal
1048 shoulder], 100). These results show that most patients obtain an excellent outcome. The best results (mean Constant score, 98) are achieved when the hook plate is removed before 6 months, which was done in the vast majority of patients (n ¼ 26). In 7 patients, there was a delay in plate removal. Of these 7 patients, 2 had a peri-implant fracture after discharge home and required a reoperation. There were 5 other delayed unions: 4 of these 5 eventually united, and the plates were removed after 7 months. Three patients have refused further surgery and have their hook plates in situ. A cadaveric morphometric assessment of the hook plate has been performed,5 which showed that there was a high rate of contact between the hook part of the hook plate and subacromial structures. Our subjective and objective functional outcome data have shown that hook plates are an effective treatment for a difficult fracture. There are excellent outcomes when the plates are removed before 6 months. Impingement symptoms can occur but tend to be confined to patients in whom there is prolonged retention of the hook plate or failure to remove the hook plate. It should be noted that postoperatively, our patients are instructed not to flex or abduct their shoulder above 90 ; this may prevent damage to subacromial structures that may occur because of contact with the hook part of the hook plate. Removing the hook plate is not universally regarded as essential, and there are reports of good outcomes without its removal.8,13 Our results have shown that functional outcomes are still good without removal of the hook plate; however, they show that after union, the earlier the plate is removed, the better the functional outcome. Because of difficulties with access to surgical beds for non-emergency surgery, in national health services, there can often be delays in plate removal.13 Our study shows that excellent outcomes are still obtainable with removal of the plate before 6 months.
Conclusion Our study shows that ORIF with the clavicle hook plate is a good option for a challenging fracture. We recommend removal of the hook plate within 6 months, because the Constant and Oxford scores are statistically significantly better. Hook plate fixation can be performed with minimal complications and union rates of up to 95%, despite almost half of the patients smoking.
Disclaimer The authors, their immediate families, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article.
D.W. Good et al.
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