Cost Comparison of Kirschner Wire Versus Intramedullary Screw Fixation of Metacarpal and Phalangeal Fractures

Abstract

Background

Intramedullary screw fixation is a relatively new technique for fixation of metacarpal and phalangeal fractures. The objective of this study was to compare health care–associated costs and outcomes for intramedullary screw versus Kirschner wire (K-wire) fixation of hand fractures.

Methods

A retrospective review of patients undergoing intramedullary screw fixation of hand fractures at a single center during 2016-2019 inclusive was conducted. Health care–associated costs were compared with age-matched and fracture pattern–matched controls who underwent K-wire fixation.

Results

Fifty patients met the study inclusion criteria, incorporating 62 fractures (29 K-wire, 33 intramedullary screw fixation). The median age was 34.6 years (18.0-90.1 years). There was no significant difference in primary operative costs (£1130.4 ± £162.7 for K-wire vs £1087.0 ± £104.2 for intramedullary screw), outpatient follow-up costs (£958.7 ± £149.4 for K-wire vs £782.4 ± £143.8 for intramedullary screw), or total health care–associated costs (£2089.1 ± £209.0 for K-wire vs £1869.4 ± £195.3 for intramedullary screw). However, follow-up costs were significantly lower for the uncomplicated intramedullary screw cohort (£847.1 ± £109.1 for K-wire vs £657.5 ± £130.8 for intramedullary screw, P = .05). Subgroup analysis also revealed that overall costs were significantly higher for buried K-wire techniques. Complication rates, time to return to active work, and Disabilities of the Arm, Shoulder, and Hand scores were similar.

Conclusions

This study identified significantly lower outpatient follow-up costs for uncomplicated intramedullary screw fixation of hand fractures compared with K-wires, along with a trend toward lower overall health care–associated costs. In addition, buried K-wire techniques were also found to carry a significantly higher financial burden. Higher powered prospective studies are required to determine indirect costs.

Introduction

Injuries to the hand account for almost a fifth of presentations to the emergency department in the United Kingdom and cost over £100 million per year to treat. ¹ Fractures represent the bulk of these injuries and require substantial multidisciplinary involvement and follow-up to ensure satisfactory return to function. ¹ This carries a significant financial cost, both to the patient and to the health care provider. ²

Numerous methods exist for surgical fixation of hand fractures, which must be tailored according to patient-related and injury-related factors. ³ Traditional techniques often involve percutaneous fixation using Kirschner wires (K-wires), which allows minimally invasive fixation while sacrificing short-term mobility. Material costs are low; however, these patients invariably require further procedures to remove the K-wires following fracture union. Moreover, protracted immobility can lead to stiffness and increased rehabilitation, further adding to the overall financial burden. A relatively newer technique uses intramedullary cannulated screws for fixation of transverse and short oblique diaphyseal or metaphyseal fractures of the metacarpals and phalanges.^4,5 Potential benefits include early mobilization, ⁶ lower complication rates, and no requirement of metalwork removal, ⁷ all of which can reduce associated costs.

There is a paucity of published cost comparisons for fracture fixation techniques in the hand. ⁸ Such analyses are an important factor in the surgical decision-making process both at an individual and at an institutional level. The aims of this study were to retrospectively analyze the health care–associated costs of using K-wires versus intramedullary screws for fixation of transverse or short oblique fractures of the metacarpals and phalanges. Secondary outcomes included complication rates, time to return to active work (RTAW), and long-term function (recorded using the Disabilities of the Arm, Shoulder, and Hand [DASH] score). ⁹

Materials and Methods

Data were collected retrospectively from medical records following institutional approval. The surgical database was searched for intramedullary screw fixation of metacarpal and phalangeal fractures from 2016 to 2019 inclusive. The inclusion criteria were patients aged over 18 years who underwent primary intramedullary screw fixation of open or closed phalangeal or metacarpal fractures at this unit. The exclusion criteria included use of multiple fracture fixation techniques, repair of multiple fractures in the same digit, fractures of the thumb, and children. Patients who underwent surgical repair of other structures during the primary procedure (eg, tendons, nerves, arteries) were also excluded as this was felt to increase the operative duration and associated costs.

As a comparator, data were also collected on age-matched and fracture pattern–matched (bone affected, fracture type, open/closed injury) patients who underwent K-wire fixation at the same unit during the year 2019. Buried and externalized K-wire fixation methods were eligible for inclusion and were used in subsequent subgroup analysis. The same exclusion criteria as the intramedullary screw group were used.

Demographic and injury details were recorded (Table 1). Number of theater episodes, operation duration, equipment costs, and number/type of follow-up appointments were used as the basis for cost analysis. Their respective cost estimates were based on data from the National Health Service national tariff payment system, ¹⁰ specialty costs published by the Information Services Division Scotland, and manufacturer product costs. ¹¹ Inpatient-associated costs (laboratory investigations, hospital stay, etc) were excluded as they were felt to be independent of the fracture fixation method.

Table 1.

Demographic and Injury Characteristics.

Demographic/injury variable	K-wire group (n = 25)	Intramedullary screw group (n = 25)	P value
Age
Mean ± SD	41.4 ± 20.7	38.7 ± 17.0	.63
Median	31.3	35.0
Range	18.3 - 90.1	18.0 - 72.2
Gender, No. (%)
Male	14 (56.0)	23 (92.0)
Female	11 (44.0)	2 (8.0)	.004
Bone, No. (%)
Metacarpal	12 (41.3)	13 (39.4)
Proximal phalanx	14 (48.3)	15 (45.5)
Middle phalanx	3 (10.3)	4 (12.1)
Distal phalanx	0 (0)	1 (3.0)
Total	29	33	.99
Fracture type, No. (%)
Transverse	19 (65.5)	23 (69.7)
Short oblique	7 (24.1)	5 (15.2)
Comminuted	3 (10.3)	5 (15.2)
Total	29	33	.62
Injury type, No. (%)
Open	8 (27.5)	6 (18.2)
Closed	21 (72.4)	27 (81.8)	.38
Operative side, No. (%)
Right	19 (65.5)	20 (60.6)
Left	10 (34.5)	13 (39.4)	.69

Note. K-wire = Kirschner wire.

P values < 0.05 are in bold.

Complications, reoperation data, RTAW, and DASH scores were collected following review of medical notes at the time of data collection.

Statistical analysis was performed using Jamovi 1.2 software. ¹² Continuous data with normal distribution were displayed as mean ± SD and 95% confidence intervals, whereas data with skew were displayed as median and range. Comparisons between both groups were made using the independent Student t test for continuous variables and χ² test for categorical data. Subgroup analysis of cost outcomes for externalized and buried K-wires versus intramedullary screws was performed using 1-way analysis of variance (ANOVA), with the post hoc Tukey procedure used to assess pairwise comparisons if results were significant and homogeneity of variances was met (assessed using the Levene test). A P value of less than .05 was considered significant. Prices are estimated per fracture, unless otherwise stated.

Results

A total of 50 patients met the study inclusion criteria, incorporating 62 fractures (29 K-wire fixation, 33 intramedullary screw fixation). The median age was 34.6 years (18.0-90.1 years). Most patients were men (74.0%), and fractures were more commonly observed in the right hand (62.9%). Demographic and injury characteristics of each group were similar (Table 1).

Primary operative time per fracture was comparable between both groups (62.5 ± 10.0 minutes for K-wire vs 66.1 ± 7.1 minutes for intramedullary screw, P = .58) (Table 2). The 7 patients who had their K-wires buried during the primary procedure all required a second trip to theater to have them removed, whereas the other 18 patients had theirs removed in outpatient clinic with an average overall cost of £202.9 ± £69.8. Implant costs were significantly higher for the intramedullary screw group (£9.7 ± £0.7 for K-wire vs £116.3 ± £0.4 for intramedullary screw, P < .01). There was no significant difference in total primary operative costs (£1130.4 ± £162.7 for K-wire vs £1087.0 ± £104.2 for intramedullary screw, P = .67).

Table 2.

Operative and Nonoperative Costs per Fracture.

Cost category	K-wire group (n = 29)	SD	95% CI	Intramedullary screw group (n = 33)	SD	95% CI	P value
Surgery costs
Primary procedure theater time, min	62.52	26.34	10.02	66.12	19.99	7.09	.58
General theater, a £	917.79	386.74	147.11	970.66	293.46	104.06	.58
K-wire removal, £	202.92	183.49	69.80	NA	NA	NA	NA
Implant, b £	9.69	1.77	0.67	116.31	1.22	0.43	<.01
Total surgical costs	1130.40	427.67	162.68	1086.97	293.95	104.23	.67
Follow-up costs c
Hand therapy appointments, £	422.40	315.70	120.09	324.00	282.06	100.02	.23
Consultant-led follow-up appointments, £	421.08	144.97	55.14	399.61	147.42	52.27	.59
Dressing clinic appointments, £	53.04	27.00	10.27	22.06	31.44	11.15	.00
Imaging, £	62.16	26.14	9.94	36.78	18.08	6.41	<.01
Total follow-up costs, £	958.68	392.65	149.36	782.44	405.50	143.79	.17
Total costs, £	2089.08	549.46	209.00	1869.41	550.65	195.25	.15

Note. CI = confidence interval; K-wire = Kirschner wire; NA = not applicable; OPA = outpatient appointment.

^aTheater costs extrapolated using pooled data published by Information Services Division Scotland for Plastic Surgery cases (1 hour = £881). ¹¹

^bImplant costs extracted from manufacturer quotes and hospital records.

^cOPA and imaging costs extracted from National Health Service England National Tariff 2019/2020. ¹⁰

P values < 0.05 are in bold.

Outpatient imaging costs were significantly higher in the K-wire group (£62.2 ± £9.9 for K-wire vs £36.8 ± £6.4 for intramedullary screw, P < .01); however, follow-up appointment costs were similar (£958.7 ± £149.4 for K-wire vs £782.4 ± £143.8 for intramedullary screw, P = .17). Subgroup analysis excluding patients who had postoperative complications (n = 4 for the K-wire group, n = 5 for the intramedullary screw group) identified significantly lower outpatient-related costs for the intramedullary screw cohort (£847.1 ± £109.1 for K-wire vs £657.5 ± £130.8 for intramedullary screw, P = .05) (Table 3).

Table 3.

Operative and Nonoperative Costs per Fracture (Complications Excluded).

Cost category	K-wire group	SD	95% CI	Intramedullary screw group	SD	95% CI	P value
Surgery costs
Primary procedure theater time, min	59.55	23.94	11.21	66.48	22.63	9.34	.34
General theater cost, a £	874.19	351.48	164.50	975.93	332.26	137.15	.34
K-wire removal cost, £	207.65	191.04	89.41	NA	NA	NA	NA
Implant cost, b £	9.8175	1.67	0.78	116.41	1.38	0.57	<.01
Total surgical costs	1091.66	416.82	195.08	1092.33	332.83	137.38	1.00
Follow-up costs per patient c
Hand therapy appointments cost, £	353.10	191.60	89.67	232.32	212.12	87.56	.06
Consultant-led follow-up appointments cost, £	379.80	114.09	53.40	366.04	132.96	54.88	.72
Dressing clinic appointments costs, £	57.20	26.77	12.53	26.00	32.05	13.23	.00
Imaging costs, £	56.98	22.58	10.57	33.15	18.38	7.59	<.01
Total nonoperative costs, £	847.08	233.04	109.07	657.51	316.75	130.75	.05
Total costs, £	1,938.74	455.19	173.14	1,749.85	509.36	180.61	.21

Note. K-wire = Kirschner wire; CI = confidence interval; NA = not applicable; OPA = outpatient appointment.

^aTheater costs extrapolated using pooled data published by Information Services Division Scotland for Plastic Surgery cases (1 hour = £881). ¹¹

^bImplant costs extracted from manufacturer quotes and hospital records.

^cOPA and imaging costs extracted from National Health Service England National Tariff 2019/2020. ¹⁰

P values < 0.05 are in bold.

There was a trend toward lower overall health care–associated costs for the intramedullary screw group (excluding reoperation costs for complications), although this did not reach significance (£2089.1 ± £209.0 for K-wire vs £1869.4 ± £195.3 for intramedullary screw, P = .15) (Table 2).

Additional subgroup analysis was performed by dividing the K-wire group into buried and externalized fixation techniques, and excluding patients who had postoperative complications (n = 4 for the K-wire group, n = 5 for the intramedullary screw group). This identified a statistically significant difference between groups as determined by 1-way ANOVA for total surgical costs (F = 3.53, P = .037), total follow-up costs (F = 3.35, P = .040), and overall health care–associated costs (F = 4.68, P = .014) (Table 4). Post hoc Tukey test revealed that the overall health care–associated costs were significantly lower for the externalized K-wire group (£1689.2 ± £197.8, P = .006) and the intramedullary screw group (£1749.9 ± £215.1, P = .013) compared with the buried K-wire group (£2299.9 ± £332.8). There was no significant difference between the intramedullary screw and externalized K-wire group for overall health care–associated costs (P = .94)

Table 4.

Operative and Nonoperative Costs per Fracture (Complications Excluded and K-wire Group Split by Technique).

Cost category	K-wire group (externalized)	SD	95% CI	K-wire group (buried)	SD	95% CI	Intramedullary screw group	SD	95% CI	P value
Surgery costs
Primary procedure theater time, min	53.35	27.23	14.00	58.43	13.88	12.83	66.48	22.63	9.34
General theater cost, a £	783.12	404.31	207.87	857.70	203.73	188.42	975.93	332.26	137.15
K-wire removal cost, £	90.59	26.28	13.51	438.71	164.19	151.85	NA	NA	NA
Implant cost, b £	9.30	1.94	1.00	10.93	1.15	1.07	116.41	1.38	0.57
Total surgical costs	882.98	423.51	217.75	1307.38	286.80	265.24	1092.33	332.83	140.54	.037
Follow-up costs per patient c
Hand therapy appointments cost, £	336.95	203.59	104.68	386.57	138.57	128.16	232.32	212.12	87.56
Consultant-led follow-up appointments cost, £	356.53	106.84	54.93	483.00	79.62	73.64	366.04	132.96	54.88
Dressing clinic appointments costs, £	59.65	20.39	10.48	59.43	33.22	30.72	26.00	32.05	13.23
Imaging costs, £	52.21	17.68	9.09	63.37	28.25	26.12	33.15	18.38	7.59
Total follow-up costs, £	753.94	243.42	125.15	929.00	153.06	141.56	624.36	316.75	130.75	.04
Total costs, £	1,689.21	384.71	197.80	2,299.89	359.89	332.84	1,749.85	509.36	215.09	.01

Note. K-wire = Kirschner wire; CI = confidence interval; NA = not applicable; OPA = outpatient appointment.

^aTheater costs extrapolated using pooled data published by Information Services Division Scotland for Plastic Surgery cases (1 hour = £881). ¹¹

^bImplant costs extracted from manufacturer quotes and hospital records.

^cOPA and imaging costs extracted from National Health Service England National Tariff 2019/2020. ¹⁰

P values < 0.05 are in bold.

Postoperative complications and reoperation rates were similar (Table 5). No significant differences were observed between DASH scores and RTAW in either group; however, many patients were lost to follow-up at this stage (9 patients in the intramedullary screw group, 15 in the K-wire group).

Table 5.

Complications and Outcomes.

Cost category	K-wire group	Intramedullary screw group	P value
Complication, No. (%)
Tendon adhesion	1 (4.0)	1 (4.0)
CRPS	2 (8.0)	3 (12.0)
Infection	1 (4.0)	1 (4.0)
Reoperation
Removal of metalwork	29 (100.0)	1 (4.0)
Adhesinolysis	1 (4.0)	1 (4.0)
Function (excluding reoperation) ± CI
DASH score	2.9 ± 1.8	3.3 ± 9.7	.17
Time to return to active work, mo	3.1 ± 1.3	3.7 ± 2.5	.63

Note. K-wire = Kirschner wire; CRPS = complex regional pain syndrome; CI = confidence interval; DASH = Disabilities of the Arm, Shoulder, and Hand.

Discussion

This study is the first to compare health care–associated costs for K-wire versus intramedullary screw fixation of metacarpal and phalangeal hand fractures. Our findings demonstrate that the operative costs are similar between both groups; however, outpatient follow-up costs were significantly lower for uncomplicated intramedullary screw fixation. Subgroup analysis revealed that intramedullary screw and externalized K-wire fixation techniques have significantly lower health care–associated costs compared with buried K-wire fixation. Complication rates and clinical outcomes were comparable. These findings provide new financial insight and contribute to the surgical decision-making process.

Operative timings for fracture fixation using K-wires and intramedullary screws were broadly similar at just over 1 hour per fracture. There was significant variance in these figures; however, interestingly subgroup analysis did not identify any association between operative timings and type or location of injury. All primary procedures were performed in the main theater with image guidance, costing an estimated £881 per hour of use, similar to international comparisons (after adjusting for inflation).^13,14 For both techniques, this was the largest single contributing factor to overall health care costs and is likely to be an underestimate considering the unrecorded downtime between cases. Undertaking small cases in minor operating theaters may be an effective strategy to reduce this financial burden. ¹³

A corollary of the main theater costs was the financial burden of K-wire removal for patients who had their K-wires buried during the primary procedure. These 7 patients (constituting 8 fractures) underwent K-wire removal in theater, at an average cost of £465.4. This was substantially higher than costs for removal in the outpatient clinic (£100.8). Moreover, this cohort of patients went on to have significantly higher outpatient follow-up costs compared with the intramedullary screw group (Table 4), predominantly due to a higher number of consultant-led outpatient clinic visits. This may indicate that burying K-wires creates a higher follow-up burden for surgeons, due to either more frequent patient contact or longer duration of monitoring. These results support the case for leaving K-wires externalized during the primary procedure to facilitate extraction. ¹⁵

Costs associated with outpatient imaging and follow-up were high, contributing to 45.9% and 41.9% of total health care expenditure for K-wires and intramedullary screw fixation, respectively. The bulk of outpatient costs, however, was due to physiotherapy and consultant-led follow-up (Table 2). Patients who had uncomplicated intramedullary screw fixation were found to have a significantly lower outpatient financial burden compared with K-wire fixation (P = .05), reflecting reduced demand for dressing and hand therapy appointments (Table 3). These findings may suggest that recovery and return to function are faster for intramedullary screws, as has been reported elsewhere in the literature. ⁷ The higher expenditure for outpatient imaging in the K-wire cohort likely represents the additional workload associated with K-wire removal.

It was particularly disappointing to note that of a total of 537 outpatient appointments booked, 69 (12.8%) were not attended by the patient, constituting £4950.0 in wasted expenditure (£99.08 per patient). This is substantially higher than the national average ¹⁶ and may reflect a sentiment that there is less need for follow-up assessment as patients are more attuned to the function of their hands postoperatively. ¹⁷ Simple and effective means to reduce these missed appointments may include appointment reminders ¹⁸ and virtual and patient-initiated follow-up.^19,20

Although this study found no overall difference in direct health care costs between these 2 fracture fixation techniques, it does not consider indirect costs such as time away from work and income lost—factors that have been estimated to contribute between 28.2% and 98.6% of total expenditure in injuries to the hand.^2,21-24 Nevertheless, our results identified no significant difference in complication rates, RTAW, or DASH scores between either group—proxies of recovery and functional status. These are consistent with findings from a retrospective comparison of intramedullary screws versus K-wire fixation for metacarpal fractures performed in Spain. ²⁵ Given the low complication rates and good functional outcomes reported with intramedullary screws,^5,7,26-27 it would be expected that indirect costs would be comparable with K-wire fixation if not lower.

Time to RTAW for intramedullary screw fixation was comparably longer in our cohort compared with other groups.^7,25 One possible explanation for this discrepancy is that there were a large number of phalangeal fractures within our cohort, which may have longer functional recovery times compared with metacarpal injuries alone.^4,7,27 In addition, given the substantial loss to follow-up within our cohort, our figures are likely to be an overestimate.

The main limitation of this study is uncontrolled confounding impacting primary operative timings. All operations were performed by senior fellows or consultants; however, there is inevitable variability in operating speed due to surgeon skill and injury complexity. Furthermore, despite broadly matching injury patterns between both groups, subtle differences between fracture types could have impacted operative timings.

An additional limitation was the difficulty in robustly analyzing functional outcomes due to significant loss to follow-up. Nonetheless, DASH scores and RTAW were similar to retrospective and prospective reports in the literature.^7,25,26

Conclusion

This study identified significantly lower outpatient follow-up costs for uncomplicated intramedullary screw fixation of hand fractures, along with a trend toward lower overall health care–associated costs. Subgroup analysis identified significantly lower health care–associated costs for uncomplicated intramedullary screw and externalized K-wire fixation versus buried K-wire fixation techniques. Complications rates and functional outcomes were comparable. Higher powered prospective studies are required to determine indirect costs.