Complications at screw removal in slipped capital femoral epiphysis treated by cannulated titanium screws

Screw Thread Configuration Has No Effect on Outcomes of In Situ Fixation for Stable Slipped Capital Femoral Epiphysis

BACKGROUND

No consensus exists regarding the optimal surgical management of slipped capital femoral epiphysis (SCFE). Treatment goals include avoiding slip progression and sequelae such as avascular necrosis (AVN). Factors associated with surgical implants merit further research. This study investigates the effect of screw thread configuration and the number of screws on surgical outcomes.

METHODS

A total of 152 patients undergoing cannulated, stainless steel, in situ screw fixation of SCFE between January 2005 and April 2018 were included. Procedure laterality, screw number and thread configuration (partially threaded/fully threaded), bilateral diagnosis, Loder classification, final follow-up, patient demographics, and endocrinopathy history were analyzed. Primary outcomes were return to the operating room (ROR), AVN, hardware failure/removal, and femoroacetabular impingement (FAI).

RESULTS

Most patients received a single (86.2%), partially threaded (81.6%) screw; most were unilateral (67.8%) and stable (79.6%). Mean follow-up was 2.0±2.7 years, with a 15.8% rate of ROR, 5.3% exhibiting AVN, 6.6% exhibiting FAI, and 9.2% experiencing hardware failure/removal. Number of screws was the sole predictor of ROR [odds ratio (OR)=3.35, 95% confidence interval (CI): 1.18-9.49]. Unstable SCFE increased the odds of AVN (OR=38.44; 95% CI: 4.35-339.50) as did older age (OR=1.43, 95% CI: 1.01-2.03). Female sex increased risk for FAI (OR=4.87, 95% CI: 1.20-19.70), and bilateral SCFE elevated risk for hardware failure/removal versus unilateral SCFE (OR=4.41, 95% CI: 1.39-14.00). Screw thread configuration had no significant effect on any outcome (for each, P ≥0.159).

CONCLUSIONS

Rates of ROR, AVN, FAI, and hardware failure/removal did not differ between patients treated with partially threaded or fully threaded screws. The use of 2 screws was associated with an increased likelihood of ROR. These findings suggest that screw thread configuration has no impact on complication rates, whereas screw number may be an important consideration in SCFE fixation.

LEVEL OF EVIDENCE

Level III-retrospective cohort study.

Implant removal of osteosynthesis. Results of a survey among Spanish orthopaedic surgeons

INTRODUCTION

The indications on extraction of osteosynthesis material are not well defined in the current literature deriving in relative indications, depending on experiences, customs or patient's request. The aim of this article is to assess the beliefs, indications, usual practice and perceived complications of surgeons in Spain regarding on extraction of osteosynthesis material.

METHODS

We conducted a questionnaire of 44 questions covering general demographics, general and subjective opinion on implant removal, specific attitudes by implant type and anatomical location, and personal habits.

RESULTS

164 questionnaires were received. The most frequent indications are patellar and olecranon cerclage wires and elastic nails in children. 56% remove the implant at the patient's request, 31% always remove it in children, 28% do it in asymptomatic patients to avoid possible surgical problems, 14% to avoid a possible peri-implant fracture and 9% by simple preference. The most frequent intraoperative complications are surgery longer than expected, bone growth over the implant, rounded screw head core, cold fusion, difficulty in finding the implant and impossibility to remove part of the implant. The most frequent postoperative complication was persistence of symptoms 39.8%.

CONCLUSION

The results provide information to advise the patient regarding the expected clinical outcome and intra and postoperative complications. The surgeon should cautiously indicate extraction in the asymptomatic patient given the high rate of complications.

Finite element analysis of different screw constructs in the treatment of unstable femoral neck fractures

OBJECTIVES

In the present study, we evaluated the mechanical outcome of different configurations formed by partially threaded screws (PTS) alone or combined screws consisting of PTS and fully threaded screws (FTS) in the treatment of unstable femoral neck fracture.

METHODS

The Pauwels type III unstable femoral fracture and screw models of PTS and FTS were created in 3-matic software and UG-NX software respectively. We assembled the different screw fixation types to the fracture model separately to form the fixation models. We used Abaqus software to perform the finite element analysis.

RESULTS

Our results indicated that the peak von Mises stresses of screws increased when some PTSs changed into FTSs in all groups except for the inferior triangle group. FTS in each group underwent the most stress while PTS underwent a little bit of stress. The combined screws fixation types were less likely to be cut-out and was more stable than PTPs alone fixation strategy. Less yielding regions around the screw tunnels for the superior and inferior triangle configuration fixed by combined screws was indicated. Superior triangle fixation model underwent the largest area of stress concentration around the screw holes after screws removal.

CONCLUSIONS

For unstable femoral neck fractures, superior results were obtained by stabilizing the fracture with superior or inferior triangle configuration consisting of one PTS and two FTSs. If screws removal was taken into account after fracture union, fixation type of inferior triangle configuration should be the recommended choice.

[Early and late complications and their management in slipped capital femoral epiphysis]

BACKGROUND

Slipped capital femoral epiphysis (SCFE) remains a challenge for the treating surgeon. First of all, SCFE should be diagnosed as early as possible. The earlier the diagnosis is made in adolescents, the lower the slip angle will be. Mild slips show more favourable long-term courses than moderate and severe SCFE.

COMPLICATIONS

With increasing slip angle, the risk of complications increases. The complications of SCFE are diverse, the most severe of which are avascular necrosis (AVN) and chondrolysis. AVN is more common in surgically treated than in non-operatively managed patients and unstable SCFE bears the highest risk of AVN.

THERAPY

Adequate treatment of AVN is still controversial. For surgical treatments, variable rates of AVN have been reported. There is a wide spectrum of surgeries for treating AVN, from hip joint-preserving techniques to total hip replacement. In central Europe there is wide consensus in favour of treating the contralateral side, but this is not without complications. Surgical treatment with in-situ pinning must be carried out with great care to take into consideration the morphology of the femoral head and not to perforate it. It should always be ensured that no osteosynthesis material penetrates the hip joint.

[Fixation techniques for slipped capital femoral epiphysis : Principles, surgical techniques, and complications]

The purpose of this review is to present the pros and cons as well as the surgical techniques of conventional implants used for fixation of slipped capital femoral epiphysis (SCFE). Worth mentioning are K‑wires, Hansson pins, transfixing screws, and gliding screws. We searched PubMed for "ECF" and "SCFE" in combination with "in situ fixation," "pin," "wire," "screw," and "nail." We considered Johansson nail, Knowles pin, and Nyström nail to be obsolete and of historical interest only. We noticed a trend from absolute stability towards some form of dynamic fixation over time, likely related to considerations of growth disturbance of the proximal femur and also the inherent potential for remodeling with time.

Slipped capital femoral epiphysis: current management strategies

In orthopedic literature, there is little consensus regarding the best management of slipped capital femoral epiphysis (SCFE). Controversies and disparate trends derive from differences in clinical presentation, various classifications, and a variety of surgical procedures that have been described. Currently, there are no evidence-based recommendations. Surgical procedures vary, and they can be divided into fixation in situ, compensatory osteotomies, and direct corrections of the deformity at the head–neck junction. The first and second group of procedures have so far not gained optimal control over the risk of avascular necrosis or cannot achieve an anatomically aligned epiphysis with normal blood supply. On the other hand, the third technique can achieve this target and prevent residual deformity and the development of early hip arthritis, but it is not widely accepted, because of its surgical complexity. The purpose of this work is to present an overview of current knowledge and provide an orientation on clinical and surgical management of the patient suffering from SCFE.

Optimum Configuration of Cannulated Compression Screws for the Fixation of Unstable Femoral Neck Fractures: Finite Element Analysis Evaluation

Objectives

In the present study, we evaluated the mechanical outcome of different configurations of cannulated compression screws for the fixation of Pauwels type III femoral neck fracture and the stress distribution around the holes corresponding to fixation protocol after screws removal.

Methods

The Pauwels type III of femoral neck fracture was created in 3-matic software and the models of cannulated compression screws were constructed using UG-NX software. Five fixation systems were assembled to the fracture models. Abaqus software was used to perform the process of finite element analysis. Values of stress distribution, maximum stress, model principal strains of proximal fragment, and stress distribution around the holes of femur model were recorded.

Results

Stress of cannulated compression screws was intensely focused on the middle area of the screw near the fragment of each group. Inverted triangle model showed the highest peak stress on screws under different phases of load. Each screw dispersed some stresses, but at least one underwent the peak stress. Fracture model fixed by inverted triangle configuration showed the lowest volume of yielding strain in the proximal fragment. The area of higher stress around the holes was largest after triangle screws removal when compared with other four models.

Conclusions

Our study indicated that different cannulated compression screws fixation configurations for the unstable femoral neck fractures showed the different mechanical efficiency. Inverted triangular configuration showed the mechanical advantage and being less likely to cutout. The fixation strategy of triangle configuration was least recommended if patients tended to remove the implants.

Outcomes after slipped capital femoral epiphysis: a population-based study with three-year follow-up

PURPOSE

To evaluate outcomes three years after treatment for slipped capital femoral epiphysis (SCFE): development of avascular necrosis (AVN), subsequent surgery, hip function and the contralateral hip.

METHODS

This prospective cohort study included a total national population of 379 children treated for SCFE between 2007 and 2013. A total of 449 hips treated for SCFE and 151 hips treated with a prophylactic fixation were identified. The Barnhöft questionnaire, a valid patient-reported outcome measure (PROM), was used.

RESULTS

In all, 90 hips had a severe slip, 61 of these were clinically unstable. AVN developed in 25 of the 449 hips. Six of 15 hips treated with capital realignment developed AVN. A peri-implant femur fracture occurred in three slipped hips and in two prophylactically pinned hips. In three of these five hips technical difficulties during surgery was identified. In 43 of 201 hips scheduled for regular follow-up a subsequent SCFE developed in the contralateral hip. Implant extraction after physeal closure was performed in 156 of 449 hips treated for SCFE and in 51 of 151 prophylactically fixed hips. Children with impaired hip function could be identified using the Barnhöft questionnaire.

CONCLUSION

Fixation in situ is justified to remain as the primary treatment of choice in SCFE. Overweight is more common in children with SCFE than in the average population. Prophylactic fixation is a safe procedure when performed using a correct technique. The number of patients who developed AVN after capital realignment is of concern. We recommend rigorous follow-up of both hips, including PROM evaluation, until physeal closure.

LEVEL OF EVIDENCE

II - prospective cohort study.

Outcomes following subcapital osteotomy for severe slipped upper femoral epiphysis

Slipped upper femoral epiphysis (SUFE) is the most common hip disorder to affect adolescents. Controversy exists over the optimal treatment of severe slips, with a continuing debate between in situ fixation versus corrective surgery. We present our experience in a series of 57 patients presenting with severe unilateral SUFE (defined > 50°) managed with a subcapital cuneiform osteotomy. Between 2001 and 2011, 57 patients (35 male, 22 female) with a mean age of 13.1 years (9.6 to 20.3, SD 2.3) were referred to our tertiary referral institution with a severe slip. The affected limb was rested in slings and springs before corrective surgery which was performed via an anterior Smith-Petersen approach. Radiographic analysis confirmed an improvement in mean head-shaft slip angle from 53.8(°) (standard deviation (SD) 3.2) pre-operatively to 9.1(°) (SD 3.1) post-operatively, with minimal associated femoral neck shortening. In total 50 (88%) patients were complication free at a mean follow-up of seven years (2.8 to 13.9 years, SD 3). Their mean Oxford hip score was 44 (37 to 48) and median visual analogue pain score was 0 out of 10 (interquartile range 0 to 4). A total of six patients (10.5%) developed avascular necrosis requiring further surgery and one (1.8%) patient developed chondrolysis but declined further intervention. This is a technically demanding operation with variable outcomes reported in the literature. We have demonstrated good results in our tertiary centre.

Current concepts in management of slipped capital femoral epiphysis

Slipped capital femoral epiphysis (SCFE) is a common hip condition that can be disabling. In this review, we provide an orientation on current trends in the clinical management of SCFE including conventional procedures and specialised surgical developments. Different methods of fixation of the epiphysis, risks of complications, and the rationale of addressing deformity, primarily or secondarily, are presented. Although improved understanding of the anatomy, vascularity and implications of residual deformity have changed management strategies, the best modality of treatment that would restore complete vascularity to the femoral head and prevent any residual deformity, impingement and early osteoarthritis remains elusive.

Management of Cannulated Screw Failure and Recurrent SCFE Displacement - Case Report

Introduction:

SCFE occurs in 10 per 100,000 in some regions of the United States with the incidence continuing to increase. Percutaneous screw fixation is a well-accepted treatment for this disorder for over 20 years but management of complications is not well elucidated in the literature.

Case Report:

We describe a case where a traumatic unstable SCFE that was initially treated with closed reduction and fixation with a single transphyseal screw went on to hardware failure with recurrence of the deformity. The complication was successfully treated with closed reduction and re-cannulating the fractured screw within the epiphysis and extracting it using a conical extraction screw commonly referred to as an “easy out.” Three trans physeal screws were then placed for improved fixation strength. Follow-up at 9 months demonstrates a fused physis and no signs of avascular necrosis of the femoral head.

Conclusion:

Percutaneous management of SCFE screw breakage is possible utilizing specialized instruments and a precise and gentle manipulation preventing the need for more invasive treatments with their obligatory potential complications profile.

Complications and associated risk factors at screw removal in slipped capital femoral epiphysis treated by cannulated stainless steel screws

PURPOSE

The aim of our study is to report our complication rate and analyze the associated risk factors when removing cannulated stainless steel screws for SCFE fixation.

METHODS

This was a multicenter retrospective study of patients who underwent removal of cannulated stainless steel screws after a mean time of 2.03 years of implantation. Thirty-two patients were included (38 hips) with a mean of 13.7 years of age during screw removal surgery. The mean post-removal follow up time was 1.6 years. In all cases the removal of screws was done systematically. Demographic data, possible risk factors related to removal failure, as well as post-removal complications such as post-removal fractures, infections and scar issues were recorded.

RESULTS

A removal failure rate of 15.79 % (6/38) was found. The removal surgical time was longer than the initial fixation time but without statistical significance (70.78 vs 61.84 m, p = 0.196). However, the duration of screw implantation (r (2): 7.09; IC: 1.12-13.06) and screw head bony coverage (r (2): 21.32; IC: 5.58-37.06) were both related to this prolonged time. Multivariant analysis revealed that a fully threaded cannulated screw had the lowest removal failure risk (OR: 0.3; IC: 0.14-0.61). There were no postremoval complications recorded.

CONCLUSIONS

We recommend to use full threaded cannulated stainless steel screws and to perform the procedure as soon as the physis are closed to decrease the surgical time. It is a safe procedure based on a low rate of complications such as post-removal fractures, infection and scar issues.

Outcomes analysis after routine removal of implants in healthy pediatric patients

Routine removal of nonspinal, orthopedic implants from pediatric patients is a debated practice. The purpose of this study was to compare preremoval and postremoval outcome measures in children. Twenty-five patients, mean age 11.6 years, completed a pain scale and the Pediatric Outcomes Data Collection Instrument (PODCI). Many patients scored in the normal range of the PODCI before and after removal. Higher postoperative PODCI scores were found in patients without preoperative pain, and in patients with upper extremity versus lower extremity implants. In summary, routine removal of implants in children was carried out without complications and with some functional benefits.

Evidence-based analysis of removal of orthopaedic implants in the pediatric population

BACKGROUND

Requested project of the Pediatric Orthopaedic Society of North America Evidenced-Based Medicine Committee.

METHODS

The English literature was systematically reviewed for scientific evidence supporting or disputing the common practice of elective removal of implants in children.

RESULTS

Several case series reported implant removal, but none contained a control group with retained implants. No articles reported long-term outcomes of retained implants in large numbers. Several small series describe complications associated with retained implants without evidence of causation. The existing literature was not amenable to a meta-analysis. By compiling data from the literature, it is possible to calculate a complication rate of 10% for implant removal surgery. The complication rate for removal of implants placed for slipped capital femoral epiphysis is 34%. Articles regarding postmarket implant surveillance and basic science were also reviewed.

CONCLUSIONS

There is no evidence in the current literature to support or refute the practice of routine implant removal in children.