|Year : 2020 | Volume
| Issue : 2 | Page : 95-98
Why do orthopedic implants break?: A retrospective analysis of implant failures at a rural tertiary care centre in central India
Rohan R Patil, Chandrashekhar M Badole, Girish B Mote, Kiran N Wandile
Department of Orthopedics, MGIMS, Sevagram, Maharashtra, India
|Date of Submission||09-Jun-2019|
|Date of Acceptance||12-Jun-2020|
|Date of Web Publication||15-Dec-2020|
Dr. Girish B Mote
Department of Orthopaedics, MGIMS, Sevagram, Maharashtra
Source of Support: None, Conflict of Interest: None
Background: The AO Foundation's Association for the Study of Internal Fixation has advocated rigid fixation with implants in the form of plates and screws. Focus is on development of implants which are stronger, more acceptable to the body, cheaper, and durable. Aim: The aim of this study was to find the factors responsible for implant breakage. Materials and Methods: We have retrospectively analyzed the data from January 2008 to December 2018 (10 years). Information on sociodemographic characteristics, clinical features, and radiographic features was retrieved from the hospital information system. Data were entered and analyzed with Epi Info software. Results: Of the 37 patients, there were 33 (89.2%) males and four (10.8%) females in the age group of 17-95 years. The most common site for implant breaks was observed to be the shaft of the femur (40.5%), and the most common type of implants which broke were locking intramedullary nails (62.1%). Conclusion: The factors responsible for breakage of implants were observed to be: retrauma, failure of compliance with advice about ambulation, absence of union at fracture sites, and persistent infection. Out study shows the importance of educating patients properly about physiotherapy and rehabilitation protocols.
Keywords: Broken implant, implant failure, union
|How to cite this article:|
Patil RR, Badole CM, Mote GB, Wandile KN. Why do orthopedic implants break?: A retrospective analysis of implant failures at a rural tertiary care centre in central India. J Mahatma Gandhi Inst Med Sci 2020;25:95-8
|How to cite this URL:|
Patil RR, Badole CM, Mote GB, Wandile KN. Why do orthopedic implants break?: A retrospective analysis of implant failures at a rural tertiary care centre in central India. J Mahatma Gandhi Inst Med Sci [serial online] 2020 [cited 2021 Apr 12];25:95-8. Available from: https://www.jmgims.co.in/text.asp?2020/25/2/95/303524
| Introduction|| |
Surgical implant devices have been used worldwide in orthopedic surgery for over 100 years. The AO Foundation's Association for the Study of Internal Fixation has advocated rigid fixation with implants in the form of plates and screws. Today, modern implants are commonly used in joint arthroplasties, spine fixation, tissue reconstruction, as well as for fracture fixation.
Stable fixation is necessary so that immediately after an operation, patients can perform active exercises of muscles and joints. Most of the focus in modern orthopedic implant development is on developing devices that are stronger, more acceptable to the body, cheaper, and durable. The biomechanical properties of corrosion/erosion resistance and adaptation to biological environments are particularly important. Metals such as cobalt–chrome alloy, stainless steel (SS), titanium, and their alloys are used for implants as they have good biological adaptation, corrosion/erosion resistance, and mechanical hardness and are cost-effective.
However, there are inherent problems with the use of these metallic devices such as stress-shielding phenomenon, pain, and local irritation.,
Apart from this, there are instances of implant failure which require revision surgeries. Implant failure is defined as the total failure of the implant to fulfill its purpose (functional, aesthetic, or phonetic) because of mechanical or biological reasons. Failed implants need to be revised. The removal of failed implants causes great expense and hardship to the patient. These revision surgeries are mostly very difficult, demanding, and time-consuming.
Hence, we initiated this study with an aim of understanding the factors responsible for breakage of implants used in fracture fixation.
| Materials and Methods|| |
This retrospective study was conducted from January 1, 2008, to December 31, 2018, in a tertiary care hospital located in a rural area in Central India.
The following criteria were employed during selection of cases. All patients diagnosed with broken implants in this period were included in this study. Patients who had complete records of previous surgery and were able to provide history were included in the study. We excluded patients who had pathological fracture.
Details of sociodemographic characteristics and clinical history were recorded. Details of mechanism of trauma, management done, postoperative ambulation, and history of recent trauma were also noted.
Radiographs were retrieved from the picture archiving and communication system and were analyzed to assess the configuration of the fracture, type of implants used, and method of fracture fixation. All these radiographs were analyzed by a senior and experienced orthopedic surgeon.
Plain radiographs were assessed to see the status of bone, level of breaking of implant, loosening, and nonunion. Intraoperative findings such as erosions/scratches, welded area over the implants, and corrosion including rusting around the broken implants, if present, were noted.
Ethical clearance was obtained from the institutional ethical committee before initiation of research. Data were entered and analyzed with Epi Info Software (Epi Info 2000, CDC, Atlanta, USA). An essentially descriptive statistical analysis was performed. Frequency and percentage were used for the categorical and ordinal variables. Mean, median, range (minimum and maximum values), and standard deviation were used for the continuous variables.
| Results|| |
Of 37 patients presenting with implant breakages, there were 33 (89.2%) males and four females with ages ranging from 17-95 years. The most common site of involvement was shaft of the femur (n= 15, 40.5%), followed by proximal femur (n = 8). These included seven cases involving the inter-trochanteric femur and one case of fracture of the neck of femur. Other sites showing breakage of implants such as shaft of the tibia and distal tibia accounted for two cases (5.5%). There were one case each of broken implants seen in the proximal and distal humerus (n = 1, 2.7%) [Table 1].
We analyzed the types of implants used. We observed that 23 (62.1%) cases were found to be managed with locking intramedullary nails. Six bones (15.2%) were managed with dynamic hip screws and barrel plates, three (8.1%) bones were managed with dynamic compression plates and screws, two (5.4%) cases with locking compression plate, and one case each of bipolar prosthesis, pedicle screw, and Enders nail [Table 2].
On the basis of history, 11 (29.7%) had a history of retrauma in the form of fall and one patient (2.7%) had a history of assault. On clinic-radiological analysis, two (5.4%) had chronic osteomyelitis, three (8.1%) cases had non-union, and one (2.7%) case each had delayed union and pseudoarthrosis [Figure 1], whereas four (10.8%) cases had faulty fixation (displacement and angulation).
Patient's non-compliance during rehabilitation and early ambulation was also found to responsible for implant failure. In our study, nine (24.3%) cases started early ambulation though they were not allowed to bear weight.
| Discussion|| |
Biocompatibility and mechanical endurance are the most crucial properties for both temporary and permanent implants. Resistance to corrosion also plays a role especially when different implants are combined such as plate and screw for internal fixation of bone fractures. In order for bones to sustain pressurized loads, they must be stiff and be able to resist deformation. They must also be flexible to absorb energy from possible deformation, shorten and widen when compressed, and to lengthen and narrow through tension without cracking.
In the present study, male preponderance was observed with male-to-female ratio of 8.2:1. Similar observation was noted by Sharma et al., where male-to-female ratio was 19.5:1. Most of the patients were in the age group of 19–59 years. This may be due to the fact that males are commonly involved in outdoor activities and have higher chances of involvement in road traffic injuries.
Of 37 cases, the most common site of implant breakage was shaft of femur (n = 15, 40.5%) and the most commonly involved implant was found to be intramedullary nails (n = 23, 62.1%). Zimmerman and Klasen found similar observations and observed that intramedullary nails fail due to fatigue of the implant due to cyclical loading. Early fatigue failure of the nail can be due to unstable fracture configuration and distal location of the fracture. As seen in [Figure 2] and [Figure 3], the fractures are located at a distal location and small diameters of nails have been used. Other causes of failure are delayed union or non-union of the fracture and in unlocked nail due to rotation of fracture fragments, since the nail might not provide rotational stability at the fracture site.
Plate failure rate was seen in 10 cases (28.7%), which were lesser than those observed by other authors., Plate failure occurs because of interference with periosteal blood supply. Brittle and plastic failure occurs due to minor loads in small plates and secondary major trauma in large plates. The most common failure of plate is fatigue failure. The ends of the plate act as stress riser leading to a fresh fracture proximal or distal to the original one. Improper application of plates and poor technique are other causes of plate failure. Fatigue failure of plate is inevitable if healing fails to occur.
Re-trauma (trauma at the original fracture site in the post operative period) was also a contributing factor. In those cases with re-trauma 11 (29.7%) had a history of fall and one patient had an assault. Sharma et al. have also found re-trauma as significant cause for implant failure in their study. The authors stated that retrauma in the consolidation phase of healing may lead to breakage of implant.
On clinic-radiological analysis, two (5.4%) patients had chronic osteomyelitis. In a study by Sharma et al., 2.4% of their cases had implant failure associated with deep infection, whereas Kumar et al. observed infection in 10 (15%) cases. Infection ranged from superficial to deep and was found to be associated with loosening of implant.
Implant-associated infections are the result of bacterial adhesion to an implant surface and subsequent biofilm formation at the implantation site. Formation of biofilm takes place in several stages, starting with rapid surface attachment, followed by multilayered bacterial cell proliferation and intercellular adhesion in an extracellular polysaccharide matrix.
Infection caused at the site of surgery can also lead to implant failure. Decreasing antibacterial activity exhibited by different materials is given in the following order: gold > titanium > cobalt > vanadium > aluminum > chromium > iron showing little resistance of stainless steel (SS) to microbial attack. The most extensive remedy for this problem is being sorted by implanting SS with silver/copper ions, which show strong antimicrobial properties to both Staphylococcus aureus and Aspergillus niger.,
It has been postulated that bones are more flexible than metal plates. Screwing a metallic plate to bone stiffens it and produces “stress risers” at each end of the plate. In the absence of union, even the strongest metal plates and screws will eventually break or pull out of bone. In the present study, three (8.1%) cases had non-union and 1 (2.7%) case each had delayed union and pseudoarthrosis. Fatigue arising from cyclic loading can cause fracture of an implant.
In our study, nine (24.3%) cases showed non-compliance to advice, that is, they resorted to early weight bearing. As seen in [Figure 4] and [Figure 5] early immobilization resulted in implant failure. Not using the commode chair in the toilet, and heavy weight lifting during rehabilitation were found to responsible for implant failure. Excessive body weight of the patient and early weight bearing on the affected lower limb imparts more stress on the implant during the healing stage of fracture. During the stance phase of gait cycle, load on the lower limb is more than three times the body weight. Ogbemudia and Umebese in their study found patient noncompliance and excessive body weight as a significant reason for the failure of implant and suggested cautious ambulation and graduated weight bearing.
|Figure 4: Broken dynamic compression plates in an operated case of shaft femur fracture|
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|Figure 5: Broken dynamic compression plates in an operated case of shaft femur fracture|
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We could not study important factors such as implant quality. Correct incidence of implant failure could not be calculated. To address the above limitation, a larger study in the form of randomized controlled trial is needed.
| Conclusion|| |
In this study, we observed retrauma, failure to comply to advice regarding ambulation, absence of union at the fracture site, and persistent infection as the factors responsible for breakage of implant. Our study shows that proper education of the patient regarding physiotherapy and rehabilitation protocol are essential to obtain better patient outcomes.
We are sincerely thankful to the Department of Orthopedics, MGIMS, Sevagram.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2]