BACKGROUND

Patellar fractures constitute ~1% of all bone fractures.1 Recently, there has been an increase in patellar fracture rates owing to an increase in transportation and industrialization.2 In patellar fractures with an intact extensor mechanism, minimal intra-articular step-off, and fracture displacement ranging from 1 to 4 mm, nonsurgical management is recommended.3 Surgery is indicated in cases of fractures with an incompetent extensor mechanism and torn extensor retinaculum.4 Because patellar fractures are commonly comminuted, it is difficult to restore and fix the articular surface. Even after treatment, complications, such as limited range of motion (ROM), weak extensor mechanism, traumatic osteoarthritis, and osteomalacia, are common.2,5

Traditionally, open reduction and internal fixation (ORIF) techniques are used to restore quadriceps function and prevent osteoarthritis.6 The AO technique, which is classically used for patellar fixation, involves axial K-wires and anterior tension banding.7 Another option is screw fixation, which is performed with or without tension banding for reinforcement.8 Metal implants are used in these techniques, which results in serious complications in 18% to 50% of patients.9–12 Patients present with soft tissue irritation over the knee, decreased ROM, sinus formation, and wire fragmentation and migration of the fragmented segments. More than 33% of patients require secondary procedures to remove the metal implants to achieve symptomatic relief.13 Recently, alternative techniques, such as heavy sutures, have been developed to overcome the disadvantages of metal implants/wires.9,14–17 Heavy sutures are associated with greater patient satisfaction and decreased rates of secondary management of complications, such as reoperations.17

In the present study, we used transosseous sutures with an all-FiberWire technique to treat patellar fractures. We presented the outcomes of this technique in managing patellar fractures in 16 patients, and we reviewed the recent literature.

METHODS

This retrospective study was conducted at Prapokklao Hospital, Chanthaburi, Thailand in the Department of Orthopaedics between April 2018 and April 2020. Sixteen patients with patellar fractures were included in the study. We enrolled both male and female patients aged above 18 years with acute fracture within 2 weeks, and simple transverse patellar fractures at the mid-patella (B2-type AO classification) or lower pole (B1-type AO classification) (Fig. 1). Patents with a skin infection over the patellar area, history of patellar surgery, and/or presenting with lower limb weakness were excluded from the study.

FIGURE 1:

Preoperative images of case no. 6.

Surgical Procedure

The patellar fractures were treated by ORIF with FiberWire (Arthrex, Naples, FL) using a 3-transosseous tunnel technique (Figs. 2, 3A–F). The patellar fracture was exposed by a vertical skin incision (Fig. 3A), and open reduction of the patellar fracture was performed with fluoroscopic guidance (Fig. 2). Three passing pins (Passing Pin; drill tip: 2.4 mm×15 mm; Smith & Nephew, Hull, UK) were inserted across the fracture site in slightly flexed positions from the inferior to superior patella (Fig. 3B). Next, double loaded sutures of No. 5 FiberWire (2 strands on a single passing pin) were anchored to the patellar tendon in the Krackow configuration (Fig. 3C). Then, the FiberWire was passed through the patella using the 3 passing pins (Fig. 3D). The FiberWire was then knotted at the superior patella with the knee fully extended (Fig. 3E). Next step, anterior tension banding (same heavy gauge steel wiring in traditionally method). The passing pins with the No. 5 FiberWire were passed through the patellar tendon inferior to the patella and quadriceps tendon, superior to the patella in a figure-of-eight pattern, followed by knotting at the superolateral surface of the patella and retinacular repair (Fig. 3F). This technique is not different among mid or inferior pole patella fracture. For lower pole patellar fractures (extra-articular), No need to reduction of the fracture. The functional outcomes were evaluated with Tegner-Lysholm and Bostman scoring. We also evaluated the clinical and radiologic outcomes.

FIGURE 2:

Case no 6: intraoperative fluoroscopy of patellar reduction and temporary passing pin fixation.

FIGURE 3:

A–F, Surgical technique in FiberWire fixation. A, Vertical skin incision to expose the fracture and patella. B, Inserting 3 passing pins cross the fracture site in a slightly flexed knee position, from the inferior to superior patella. C, Running Krackow suture using 2 loops from the patellar tendon with no. 5 FiberWire. D, Passing the FiberWire though the patella by passing 3 passing pins. E, Knotting the FiberWire at the superior patella with the knee in full extension. F, Passing the passing pin with no. 5 FiberWire though the patellar tendon inferior to the patella and quadriceps tendon and superior to the patella in a figure-of-eight loop then knotting at the superolateral patella.

Data Presentation and Statistics

Continuous variables were presented as mean±SD and range (minimum, maximum), and categorical variables were presented as frequency (%). Descriptive statistics was analyzed using SPSS version 21 (IBM Corp., Armonk, NY).

RESULTS

Table 1 presents the patients’ demographic and clinical details; complete clinical and radiologic follow-up data were available for 16 patients. Figure 4 shows the postoperative and follow-up images without removal of the FiberWire (patient no. 6). Of the 16 patients, 11 (68.75%) were male and 5 (31.25%) were female, and the mean patients’ age was 46.19 years (range, 19 to 88 y). In the majority of the patients (n=12, 75%), the mechanism of injury was a motorcycle accident, and in the remainder of the patients (n=4, 25%), the mechanism of injury was a fall from a height. There were 4 comminuted (25%); 5 simple, mid-patellar (31.25%); and 7 simple, lower-pole patellar fractures (43.75%). The mean follow-up period was 17.5 months (range, 9 to 32 mo). None of the patients developed significant flexion contracture. The mean ROM was 126.25 degrees in flexion (range, 120 to 130 degrees) and 0.63 degrees for extension (range, 0 to 10 degrees). We observe no significant difference in ROM compared with the uninjured contralateral knee. The mean Bostman score at the final follow-up was 27.13±2.5 (range, 21 to 30), and the mean Lysholm score at the final follow-up was 90.69±5.75 (range, 83 to 100).

TABLE 1 - Demographic Data and Clinical Outcomes after Patellar Fracture Fixation Using FiberWire and 3 Transosseous Tunnels Case Number Sex Age (y) Mechanism of Fracture Type of Fracture Follow-up (mo) Bostman Scores Lysholm Score Complications 1 Male 44 MCA Minimally comminuted, mid-patella 10 26 85 — 2 Male 84 Fall Simple, mid-patella 15 21 83 Infected hematoma 3 Male 35 MCA Simple, lower-pole patella 18 30 100 — 4 Female 88 Fall Comminuted, lower-pole patella 24 24 85 Mild symptoms 5 Male 20 MCA Comminuted, mid-patella 15 29 99 Slight loss of reduction (1 mm) 6 Male 40 MCA Minimally comminuted, mid-patella 30 28 95 — 7 Female 56 Fall Simple, lower-pole patella 10 28 90 — 8 Female 20 MCA Comminuted, mid-patella 12 25 85 Slight loss of reduction (2 mm) 9 Male 56 MCA Simple, lower-pole patella 22 29 90 — 10 Male 30 MCA Simple, lower-pole patella 26 30 100 — 11 Male 46 MCA Simple, lower-pole patella 32 27 86 Mild symptoms 12 Female 64 Fall Simple, lower-pole patella 11 26 90 Slight loss of reduction (2 mm) 13 Female 42 MCA Simple, mid-patella 9 30 94 — 14 Male 19 MCA Simple, lower-pole patella 10 25 85 — 15 Male 49 MCA Simple, mid-patella 17 28 94 — 16 Male 46 MCA Simple, mid-patella 19 28 90 —

MCA indicates motorcycle accident.

FIGURE 4:

Postoperative and follow-up images showing the FiberWire sutures, which were not removed.

Fractures healed in all patients, with no fixation failures, and the mean time to union was 8.87±1.54 weeks (range, 7 to 12 wk).

Minor losses in reduction (<2 mm) were observed in 3 patients (18.75%); 1 patient showed a 1-mm loss of reduction 7 weeks postoperatively, and 2 patients showed 2-mm losses of reduction 10 weeks postoperatively. None of patient required reoperation.

One patient developed minimal knee stiffness with an infected hematoma 10 weeks postoperatively. This patient was treated with 81 mg of aspirin once daily. The treatment was local incision and drainage, and intravenous antibiotics for 7 days. Resuturing was performed after good wound healing was achieved. This patient also experienced knee stiffness and required prolonged rehabilitation.

None of the patients developed anterior knee pain postoperatively. Two patients (12.5%) presented with mild localized pain from prominent suture knots; however, they required no further management, and the symptoms disappeared 6 months postoperatively.

DISCUSSION AND LITERATURE REVIEW

In this retrospective study, we functionally evaluated ORIF with FiberWire using a 3-transosseous tunnel technique to threat patellar fractures. Transosseous sutures with an all-FiberWire technique showed favorable clinical outcomes with minimal associated postoperative complications. All of the fractures achieved bony union, with no fixation failures, and none of the patients reported implant-related complaints.

Several surgical methods have been used to treat patellar fractures, such as heavy gauge steel wire fixation, tension band wiring, percutaneous fixation, and arthroscopic fixation.5,10,18 However, these methods are relatively complicated and have disadvantages. Among these surgical methods, percutaneous methods are simpler and efficiently preserve the blood flow in the bony fragments. However, owing to interference by hematomas or tendon fibers, there is always a possibility of inaccurate reduction, and the ruptured retinaculum cannot be restored. Therefore, percutaneous methods are suitable for repairing simple nondisplaced fractures.18 Although arthroscopic surgery is associated with accurate reduction, early recovery, and relatively less postoperative pain, this approach is also suitable for simple nondisplaced fractures and is unsuitable for fractures associated with a ruptured extensor mechanism.19

Several clinically proven methods are used to treat patellar fractures, in practice. Conventionally, the tension-band technique using 2 axial K-wires and a figure-of-eight wire placed anteriorly is used to treat transverse fractures.20 In cases of comminuted fractures, this technique has been used in combination with screws.4

A study by Levack et al5 highlighted that tension band wiring resulted in accurate reduction and firm fixation. A cadaver study showed that retinacular repair resulted in greater knee joint stability, and modified tension band wire fixation resulted in minimal fracture fragment displacement compared with heavy gauge steel wire or tension band wire fixation. Retinacular repair resulted in more rigid fixation in transverse fractures.21 Longitudinal anterior bands with cerclage wire and retinacular repair is also recommended to fix transverse patellar fractures.22 The mentioned techniques use heavy gauge steel wire fixation, longitudinal wire fixation, and AO anterior tension band fixation.

Modified tension band wiring is another widely used technique to treat patellar fractures. This method results in successful clinical outcomes2,5,10; however, the major disadvantage is that this method cannot be used to treat severely comminuted displaced fractures. Additional complications associated with this method are irritation caused by the metal, displacement of the K-wire and heavy gauge steel wire, and loss of reduction. It has been reported that 10% of patients required internal fixation owing to soft tissue irritation caused by the K-wire or heavy gauge steel wire.10 Furthermore, Berg et al23 demonstrated that fixation with 2 cannulated screws combined with anterior tension band wiring reduced soft tissue injury caused by the metal. This combination technique also maximized fixation and prevented anterior angulation.

In another study, K-wires and FiberWire were used instead of the heavy gauge steel wire to execute tension band wiring in both simple and comminuted transverse patellar fractures. This method was easy to perform and reduced irritation and wire breakage.24 However, there are several disadvantages and difficulties when using heavy gauge steel wire to fix patellar fractures. Wires are difficult to direct through the tissues and are associated with poor fracture unions.9 In in addition, several adverse effects associated with metal implants resulted in removal of the implants. In as many as 60% of cases, K-wire disintegration and migration and skin irritation were reported,2,25 and the majority of these cases required implant removal. In a study involving 27 patients, >50% of the patients required implant removal at a mean of 6.5 years of follow-up.26 However, implant removal rates vary in different studies. In a retrospective study of patients who underwent patellar fracture surgery, the metal implant removal rate was 37% in patients treated with K-wires and 23% in patients treated with screws.27

To overcome the disadvantages of heavy gauge steel wire, several studies have used nonmetallic implants, such as nonabsorbable suture and biodegradable cannulated screws.9,14,15,28–30 Most of these studies showed favorable clinical outcomes, with minimal postoperative complications (Table 214,28,29,31–42).

TABLE 2 - Important Studies Highlighting the Use of Nonmetallic Sutures in Patellar Fracture Fixation Study No. References No. Patients Type of Study Type of Fracture Technique Used Outcome Time to Bony Union (Average) Scores Complications 1 Adjal and Ban31 6 Prospective Patellar fractures Suture tension band fixation (K-wires and cerclage) All fractures achieved bony union NA Lysholm score: 90 points in 5 patients and 78 in 1 patient None 2 Monaco et al32 1 Case report Transverse patellar fractures High-resistance tape (FiberTape; Arthrex, Naples, FL) and a tensioner (Arthrex) Fracture achieved bony union NA NA None 3 Shea et al33 Suture:13, hybrid: 17, metal: 57 Prospective Patellar fractures Compared suture fixation (transosseous sutures and figure-of-eight tension banding with FiberWire), hybrid fixation (transosseous FiberWire sutures and metal tension banding), and metal fixation Suture: all fractures achieved bony union except in 1 patient NA Suture fixation was the best among the 3 techniques 2/13: reoperation required; 1 patient: soft tissue irritation; fixation failure/displacement ≥3 mm in 1 patient 4 Lee at al24 63 Retrospective Comminuted patellar fractures Modified tension band wiring using FiberWire Nonunion with deformity in 1 patient 5.6 mo Levack’s scoring system: 58 patients were rated as excellent and 5 patients as good Loss of reduction and signs of infection were observed in 1 patient 5 Busel et al34 50 Retrospective Patellar fractures Cannulated lag screws and FiberWire tension band 96% (48/50) achieved primary bony union 3 mo NA Infection in 3 patients, 1 patient showed prominent suture knots 6 Anand et al35 24 Prospective Transverse fractures FiberTape (Arthrex) using a novel transosseous tunnel technique All fractures achieved bony union 3 mo, 8 d Lysholm: 96, Bostman: 27 Superficial infection, displacement <4 mm, anterior knee pain, and extensor lag ∼10 degrees: 4 patients; no hardware-related complications, none required repeat surgery 7 Sisodia et al36 25 Prospective Closed displaced transverse patellar fractures Transosseous fixation with endobuttons All fractures achieved bony union NA Rasmussen’s knee score was excellent in 72% of the cases, good in 20%, and fair in 8% Tilting of the endobuttons was present in 4 cases, but it did not affect fracture union; no other complications were seen 8 Srikant et al37 10 Prospective Comminuted, extraarticular, inferior pole patellar fractures Partial patellectomy and patellar tendon repair by transosseous sutures All fractures achieved bony union NA Bostman: 25.6 Superficial infection in 1 patient 9 Camarda et al38 17 Retrospective Displaced patellar fractures Open reduction and internal fixation with a modified tension band using FiberWire sutures All fractures achieved bony union 9.2±2 wk Lysholm: 91±5.7 Bostman: 28.3±1.6 Slight losses of reduction (<4 mm) were noted in 2 patients at 4 wk 10 Buezo et al39 8 Retrospective Comminuted fractures: 5, transverse patellar fractures: 3 Open reduction followed by internal fixation with transosseous sutures All fractures achieved bony union 6.2 wk NA No complications (1 patient developed a 2-mm cartilage step-off secondary to an accidental fall and developed patellar tendinosis) 11 Bryant et al40 13 Prospective Induced transverse patellar fractures (in cadaver knees) Compared FiberWire with stainless steel wire Both techniques provided similar protection against repair displacement NA NA NA 12 Egol et al41 49 Retrospective Transverse patellar fractures Compared suture fixation and tension band fixation (K-wire or cannulated screws with tension band) Suture fixation was equal or better than wire fixation NA Lysholm score: suture group: 82 (56-100); wire fixation: 78.4 (22-100) Patients who underwent suture repair had fewer hardware-related postoperative complications than those who received wire fixation 13 Chen et al28 25 Prospective Displaced patellar fractures Transosseous suturing technique All fractures achieved bony union 8.43±2.92 wk NA Skin irritation in 1 patient 14 Qi et al29 15 Prospective 12 transverse patellar fractures and 3 comminuted patellar fractures Bioabsorbable cannulated screw + braided polyester suture All fractures achieved bony union 3 mo 86.7 None 15 Gosal et al14 AO technique using stainless steel wire: 21; nonabsorbable polyester: 16 Retrospective 7 transverse, 1 upper pole, 8 comminuted patellar fractures Compared AO technique using stainless steel wire with nonabsorbable polyester All fractures achieved bony union in the nonabsorbable polyester fixation group, but bony union was not observed in 1 patient in the metal wire fixation group 3.71 mo in the metal wire fixation group and 3.75 mo in the nonabsorbable polyester fixation group NA 3 patients developed postoperative infection and required wire removal in the stainless steel wire group; none developed infections in the nonabsorbable polyester group, and only 1 patient required tension band wiring 16 Juutilainen et al42 10 Prospective Fractures with 2 or 3 fragments without additional fragmentation Compared biodegradable implants with metal implants All fractures achieved bony union; both methods were equally efficient NA NA No complications

NA indicates not available.

The FiberWire is a suture with a core of several small, individual strands of ultra-high-molecular-weight polyethylene that is covered with braided polyester suture material. Double-strand FiberWire is associated with significantly higher failure loads compared with heavy gauge steel wire, and in contrast to heavy gauge steel wire, FiberWire maintains its initial stiffness until failure.43 One study reported that all fractures treated with FiberWire achieved bony union 3 months postoperatively, and none of the patients developed significant fracture displacement postoperatively. The study concluded that FiberWire tension bands are an appropriate alternative to heavy gauge steel wire tension bands in treating patellar fractures.38 In contrast to these findings, in the present study, all patients achieved bony union at a mean of 8.87±1.54 weeks postoperatively, and the patients’ clinical outcomes were graded as excellent according to Bostman and Lysholm scores. Furthermore, there were no fixation failures or major postoperative complications. However, slight losses of reduction (<4 mm) were observed in 3 patients (18.75%), and 1 patient developed knee stiffness with an infected hematoma 10 weeks post-operatively. None of the patients developed anterior knee pain post-operatively, and only 2 patients (12.5%) presented with mild localized pain from prominent suture knots. No further management was required in these patients, and the symptoms subsided 6 months post-operatively.

Table 2 summarizes the findings of similar studies that have used nonmetal sutures to treat patellar fractures. All of these studies show the advantageous aspects of the transosseous suture and FiberWire methods to treat patellar fractures. The present study further justifies the use of transosseous sutures with an all-FiberWire technique to treat patellar fractures. One of the most important advantages of this technique over the metal wire technique is that it can be used for both mid-patellar and lower-pole patellar fractures. In the all-FiberWire technique, Krackow suture loops are placed in the patellar tendon. The suture loops are strong enough (bone-tendon junction) and allow efficient fracture healing. The transosseous all-FiberWire suture technique is better than K-wire fixation because it is easy to achieve a tension band effect compared with K-wire fixation. The problem with K-wire fixation is that if the 2 K-wires passing though patella are not parallel, a tension band effect cannot be achieved. Compared with K-wire fixation, which uses tension force, suture loops utilize compression force, which is more effective and permits early motion and good bone healing.

Limitations

The sample size of this study was small; however, previous studies have reported similar findings with similar or even smaller samples. To address this issue, we included only truly representative cases. We recommend that further large-scale randomized trials involving larger samples should be performed to further validate our findings.

CONCLUSIONS

The high-resistance nonmetallic suture technique using FiberWire resulted in complete bony union of patellar fractures without significant implant-related complications. Therefore, the use of nonmetallic all-FiberWire sutures avoided reoperations to remove metal implants because of associated postoperative complications. The high-resistance FiberWire sutures were effective in patellar fracture fixation.

ACKNOWLEDGMENTS

The authors thank Suppatisa Roddara for her help creating the illustrations of the surgical techniques. They thank Jane Charbonneau, DVM, from Edanz Group (https://www.edanz.com/ac) for English editing a draft of this manuscript.

REFERENCES 1. Bostrom A. Fracture of the patella. A study of 422 patellar fractures. Acta Orthop Scand. 1972;43(suppl 143):1–80. 2. Carpenter JE, Kasman R, Matthews LS. Fractures of the patella. Instr Course Lect. 1994;43:97–108. 3. Carpenter JE, Kasman R, Matthews LS. Fractures of the patella. J Bone Joint Sur Am. 1993;75:1550–1561. 4. Carpenter JE, Kasman RA, Patel N, et al. Biomechanical evaluation of current patella fracture fixation techniques. J Orthop Trauma. 1997;11:351–356. 5. Levack B, Flannagan JP, Hobbs S. Results of surgical treatment of patellar fractures. J Bone Joint Surg Br. 1985;67:416–419. 6. Kakazu R, Archdeacon MT. Surgical management of patellar fractures. Orthop Clin North Am. 2016;47:77–83. 7. Curtis MJ. Internal fixation for fractures of the patella. A comparison of two methods. J Bone Joint Surg Br. 1990;72:280–282. 8. Tian Y, Zhou F, Ji H, et al. Cannulated screw and cable are superior to modified tension band in the treatment of transverse patella fractures. Clin Orthop Relat Res. 2011;469:3429–3435. 9. Chatakondu SC, Abhaykumar S, Elliott DS. The use of non-absorbable suture in the fixation of patellar fractures: a preliminary report. Injury. 1998;29:23–27. 10. Hung LK, Chan KM, Chow YN, et al. Fractured patella: operative treatment using the tension band principle. Injury. 1985;16:343–347. 11. Smith ST, Cramer KE, Karges DE, et al. Early complications in the operative treatment of patellar fractures. J Orthop Trauma. 1997;11:183–187. 12. Wu CC, Tai CL, Chen WJ. Patellar tension band wiring: a revised technique. Arch Orthop Trauma Surg. 2001;121:12–16. 13. Lazaro LE, Wellman DS, Sauro G, et al. Outcomes after operative fixation of complete articular patellar fractures: assessment of functional impairment. J Bone Joint Surg Am. 2013;95:e96 1–e96 8. 14. Gosal HS, Singh P, Field RE. Clinical experience of patellar fracture fixation using metal wire or non-absorbable polyester—a study of 37 cases. Injury. 2001;32:129–135. 15. Hughes SC, Stott PM, Hearnden AJ, et al. A new and effective tension-band braided polyester suture technique for transverse patellar fracture fixation. Injury. 2007;38:212–222. 16. McGreal G, Reidy D, Joy A, et al. The biomechanical evaluation of polyester as a tension band for the internal fixation of patellar fractures. J Med Eng Technol. 1999;23:53–56. 17. Patel VR, Parks BG, Wang Y, et al. Fixation of patellar fractures with braided polyester suture: a biomechanical study. Injury. 2000;31:1–6.