Percutaneous elevation of proximal tibia depressed fractures using modified new instrument

Abstract

Proximal tibia depression fracture often occur isolated or in conjunction with complex fracture presentations and elevation of such depression is required to retard arthritis in long term. Conventional open reduction by sub meniscal approach has many percutaneous alternatives from arthroscopy assisted reduction to balloon tibioplasty. Few authors even reported usage of PCL jig and percutaneous pins to elevate, while the primary author has previously described an instrument to elevate the depressed fragment percutaneously. With the shortcomings of the same instrument, authors have designed modifications in the same to address anterior and posterior extensions of depression without widening the metaphyseal window. In this article, we describe the size and concept of the modified design and its efficacy to address depression injuries.

1. Introduction

Proximal tibia depression fractures typically present in isolation or in association with complex fracture patterns depending on the mechanism of injury involved. These depression injuries are located either centrally or found extending to anterior or posterior part of affected condyle based on flexion or extension injury mechanism.¹ Injury mechanism in proximal tibia depressed fractures is a result of imprint of femoral condyles as a part of loading injury and when it occurs in combination of shear/translation it leads to ligament injuries. Lateral plateau is more affected (55–70%) as a result of injuries that accentuates normal tibiofemoral valgus.² Depression fractures, when not reduced accurately will lead to articular step and in long term lead to unfavorable results. Most direct impact injuries also pose a soft tissue problem around, making it more difficult to access by open methods. Surgical incisions made through the damaged soft tissues around have complications often from wound healing.³ Percutaneous approach for management of such injuries will be appealing as they minimize complications related to wound.

Several percutaneous techniques for elevating the proximal tibia depressed fragments are used widely. Elevation using the bone punches through metaphyseal window is the most commonly performed technique. Arthroscopy assisted reduction to confirm accuracy of articular reduction by indirect reduction methods replaced open sub meniscular window to check for articular congruity.⁴ Inspired from vertebral kyphoplasty, balloon tibioplasty to elevate depressed tibial condyles are also used.^3,5 Chan et al. used the concept of sequential tunnel drilling in ligament reconstruction and applied it for bone impaction by tunnel creation beneath the articular step with a PCL (posterior cruciate ligament) jig.⁶ Sundaram et al. demonstrated an alternate percutaneous pin leverage technique to effectively reduce selected central and posterior depression fracture of the lateral tibial plateau without the need for bone grafting.⁷ In 2012, primary author (VSR) has designed an instrument, which can make a window by hollow mill design and an inner telescopic punch to raise the depressed fragment and demonstrated its advantage of utilizing cortical window graft to support the depressed fragment.⁸ With the use of straight bone punches or metallic tamps, author has noticed widening of the metaphyseal window while addressing the anterior or posterior extensions of the depression. To avoid the metaphyseal window widening which can be a stress raiser, the author (VSR) had modified this instrument with a curvature, so as to address even posterior and anterior components of proximal tibia depression. In this article, we describe the size and concept of the modified design and its efficacy.

2. Modified instrument design [Fig. 1]

Fig. 1.

Instrument design. Fig. 1a) Design of the instrument. Fig. 1b) Dimensions of the instrument.

Two 316L hollow tube of outer diameter 10 mm & 8 mm and with a wall thickness of 1 mm were used. Length of Outer tube is 183 mm and inner tube is 258 mm to allow it to piston through and to elevate the depressed fragment. Laser marking of ruler done on both the tubes to aid for assessment of depth of penetration in to proximal tibia through the metaphyseal bony window. Tubes are concentrically bent, so as to allow telescoping of the outer and inner tubes easily without any friction. Radius of curvature of the bend made for outer tube is 572 mm and inner tube is 570 mm. To allow a T handle grip, handles are attached to one end of both the tubes, perpendicular to the plane of curvature for an ergonomic design. Serrations are made with a depth of 2.7 mm and an angulation of 70° to each other, on the other end of the outer tube to facilitate hollow mill effect for easy creation of a metaphyseal bone window entry. End of the Inner tube is closed to mimic a bone punch, that can be used for elevation of depressed fragment.

3. Indications

This device is primarily suitable to use in elevating depression injury patterns of Schatzker type II & III Fig. 2 proximal tibia fractures. Articular depression injuries in type V & VI, can be elevated directly through fracture site as a part of open reduction and use of this instrument in type II & III injuries justifies percutaneous approach.

Fig. 2.

Pre op images of Proximal tibia depression fracture – Fig. 2A) AP and lateral views and Fig. 2B) 3D CT demonstrating central fracture depression.

4. Surgical steps [Fig. 3]

Fig. 3.

Intra operative steps in using the instrument. Fig. 3A) Clinical pic showing percutaneous metaphyseal window made and outer hollow mill tube inserted. Fig. 3b) Sequential fluoroscopic pictures of instrument elevating the depressed fragments. Fig. 3c) Proximal tibia depression fixed percutaneously with cc screws. Fig. 3d) Follow up x ray after fracture healing.

AP, Lateral and CT images of proximal tibia are carefully studied to observe the fracture pattern of depressed fragments. Depending on the morphology and location of depressed fragment, the entry point of metaphyseal window is planned on the basis that the inner rod (elevation punch) device should be placed perpendicular to the depressed fragment in all the planes for accurate elevation. Pre requisite is to check that the cortical rim adjacent to the depressed fragment is intact, so as to avoid further widening of fracture upon elevation.

A 1.8 mm long guide wire is aimed percutaneously under C-arm guidance, centering the depressed fragment and perpendicular to it in both AP and lateral view. A 1 cm skin incision is made centering the guide wire. Outer tube of the instrument is placed over this k wire and by gentle rotation and tapping with mallet, cortical window is made and the tube is advanced to about 2–3 cm in to the bone. Guide wire is then removed and inner tube matching the curvature of the outer tube is slowly passed and used to elevate the depressed fragment. Serial C-arm shoots to know amount of advancement can be minimized by using the ruler markings on both the tubes. Once, the required elevation of the depressed fragment is achieved, the inner punch is retained till a guide wire is passed through sub chondral region and fixed with screw. Depending on the fracture configurations, fixations can be done using 6.5/7.0 mm cc (cannulated cancellous) screws or a 3.5 mm plate to buttress the adjacent cortical fragment wherever required.

5. Discussion

CT scan for articular fractures demonstrate morphology of fracture pattern more clearly, depression fractures in particularly. When the depression fractures are associated with split fracture, open book technique and windowing technique of reduction are commonly performed.⁹ Percutaneous techniques associated with percutaneous fixation preserve the periosteal blood supply, unlike the open methods of reduction which not only widely damages it, but also increases the risk of infection and nonunion. Also the open reduction needs a submeniscal arthrotomy which in some cases, needs cutting of the transverse ligament that joins the anterior meniscal horns that can increase the risk of stiffness, proprioceptive deficits.² Isolated depression fractures of proximal tibia can be addressed by PRIF (Percutaneous Reduction and Internal Fixation) by arthroscopic reduction,⁴ ballon tibioplasty,⁵ PCL jig,⁶ joy stick methods⁷ and bone punches.

Balloon tibioplasty often needs filling of the cavity formed by the balloon, as a result of compression of the cancellous bone not only underneath the depressed fragment but also over the surrounding areas as the balloon inflates circumferentially. This void needs to be filled up as the void is large, usually by calcium phosphate bone cement through the same trochar.⁵

Need for filling up the void using other techniques depends on the size of the void and fracture configurations. Allograft¹⁰ to pack the void is used to avoid morbidity related to bone graft harvesting from iliac crest,¹¹ but the introduction of calcium phosphate cement which has a higher resistance to load stress has an additional advantage with respect to strength and also avoiding any morbidity.¹² Weinmann et al.¹³ demonstrated jail screw construct which consists of two raft screws with an additional anterior to posterior screw supporting the raft screw subsidence in the void area.

The present modified instrument is a combination of hollow mill and bone punch telescoping in to one another with a radius of curvature which allows it to toggle through the same metaphyseal window without any widening. This instrument minimizes the need for additional instruments required for making bone window or a punch as it has a capability to make circular osteotomy using hollow mill design of outer tube. Circular osteotomy created by this instrument has width of 10 mm only, which has less stress on the metaphyseal part of proximal tibia.¹⁴ The outer tube with hollow mill design not only makes a circular bony window, but also cores the metaphyseal bone as it is advanced. This tubular metaphyseal bone cored along the entry point by outer tube is gently rammed in to the subchondral region, by the inner tube that punches and elevates the depressed fragment, thereby filling up the void created after elevation of the depressed fragment [Fig. 4].

Fig. 4.

Demonstration of punching in cortical metaphyseal bone cored by hollow mill to support the subchondral bone providing additional support to the depressed fragment after elevation, thereby avoiding any need of grafting.

The success of using this instrument depends on a good understanding of its indications and limitations. This instrument is recommended for depressed plateau fractures with single large anterior or posterior or central fragment with depression in either coronal or sagittal plane. The advantages of this instrument are it is minimally invasive, requires no other instruments to make a bone window or a bone punch separately, and avoiding bone graft in subchondral region to support the elevated depressed bone. It allows controlled elevation due to the presence of ruler marking without excess radiographic views. It is difficult to perform in comminuted depressed fractures. It is also not indicated in fractures associated with displaced adjacent condyle, in which case direct open reduction and fixation is needed. No major complications related to the technique were noted in our experience. A long term follow up, potential use in osteoporotic bones and ability to reproduce technically are the limitations.

6. Conclusion

This instrument promises to be a true percutaneous tool for effectively creating a circular osteotomy due to its hollow mill design and ability to ram the tubular graft of window under the subchondral bone, thereby avoiding additional bone graft or substitutes to fill the void. Addition of curvature in the instrument helps in addressing anterior or posterior through the same window without widening of entry point. Elevation following percutaneous reduction and internal fixations (PRIF) are effective minimally invasive approaches yielding good outcomes particularly in immediate post operative period.

CRediT authorship contribution statement

V.S. Ravindranath: Conceptualization, Validation, Investigation, Methodology, Writing – review & editing. Ranjith Kumar Yalamanchili: Validation, Methodology, Writing – original draft, Project administration, Resources. Sukarna Reddy Palla: Investigation, Methodology, Supervision. Venu Madhav Vuthpala: Investigation, Methodology, Data curation. Anand Reddy Baddula: Investigation, Methodology. Praveen Singh: Methodology, Data curation.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.