CASE STUDY: 2 INBONE Total Ankle Replacement System in a ... · CASE STUDY: 2 INBONE® Total Ankle...

CASE STUDY: 2 INBONE® Total Ankle Replacement System in a Patient with Painful Varus Hindfoot Deformity

Contributed by:Steven L. Haddad, MD*Illinois Bone and Joint InstituteGlenview, IL

*Dr. Haddad is a paid consultant for Wright Medical Group N.V. Wright Medical Group N.V. provided financial support for this case study.

These results are specific to this individual only. Individual results and activity levels after surgery vary and depend on many factors including age, weight, and prior activity level. There are risks and recovery times associated with surgery, and there are certain individuals who should not undergo surgery.

This case study is a publication of Wright Medical Group N.V.™ and ® denote Trademarks and Registered Trademarks of Wright Medical Group N.V. or its affiliates.

CASE STUDY INBONE™ II Total Ankle

Replacement System

1

Dr. Haddad is a paid consultant for Wright Medical Technology, Inc. Wright Medical Technology, Inc. provided financial support for this case study.

These results are specific to this individual only. Individual results and activity levels after surgery vary and depend on many factors including age, weight and prior activity level. There are risks and recovery times associated with surgery, and there are certain individuals who should not undergo surgery.

**Postoperative care is the responsibility of the medical professional.

This case study is a publication of Wright Medical Technology, Inc.

™ and ® denote Trademarks and Registered Trademarks of Wright Medical Group N.V. or its affiliates.

Patient History and Prior Surgery

Patient presented as a 63-year-old gentleman with a painfully deformed left ankle and hindfoot. His history included four separate incidents of fracture about his foot and ankle, (FIGURES 1A, 1B, 1C, 1D) the last one occurring 25 years prior. Over the past year, his ankle deformity had increased, causing him to walk on the outside of his foot with no flexion in his ankle. At presentation, he described the extremity as like a “club,” without normal propulsion. He had an arthroscopy of his ankle one year prior (performed elsewhere), and he noted that the deformity progressed after that procedure, as did his pain. He had failed brace management.

1A

FIGURES 1A,1B, 1C,1D: Clinical presentation of the patient.

1B

1C

1D


Replacement System

2






2A

2B

2C

Discussion of Pathology

Patient had pathology on multiple levels: an anterior extruded talus with significant varus deformity of 25 degrees clinically; (FIGURES 2A, 2B, 2C) motion restricted to -5 degrees dorsiflexion and 25 degrees plantarflexion, though both of these measurements are artificial given the ankle was not articulating; grossly unstable ankle with respect to deformity, but rigid in the sense that the deformity is not correctable. The significant ligament pathology would mandate a non-anatomic repair should he choose total ankle replacement (TAR).

FIGURES 2A,2B, 2C: Preoperative lateral, mortise, and axial view x-rays.


Replacement System

3






FIGURE 3A,3B,3C: Preoperative CT study showing the varus deformity.

3A

3B

3C

Discussion of Pathology...continued

CT scan showed his bone quality to be sufficient (FIGURE 3A), and this was critical in determining his ability to heal following either fusion or TAR. However, he had significant adjacent joint arthritis at the subtalar joint. Coronal plane CT imaging revealed additional pathology, including the erosion of the medial distal tibia and the medial translation of the calcaneus upon the talus, accentuating the varus deformity (FIGURES 3B, 3C).


Replacement System

4






Treatment Plan

Patient preferred to consider total ankle replacement. This was not an unreasonable request from someone with pre-existing adjacent joint arthritis, as fusion of the ankle here would require an additional subtalar joint arthrodesis, and invariably over time, the talonavicular joint would continue to erode, potentially creating the need for conversion to a pantalar arthrodesis. Gait mechanics can be so significantly disrupted following pantalar fusion that a below knee amputation is a valid alternative treatment option. With that in mind, arthroplasty became a valid consideration.

Patient understood the technical difficulty in his ankle reconstruction and further understood that the treatment plan would require two surgical stages: a subtalar fusion in the first surgery, and total ankle arthroplasty in the second surgery. There were two primary reasons for this staging. First, performing a subtalar fusion at the same time as a total ankle arthroplasty is believed to compromise the talar blood supply, resulting in avascular necrosis of the talus. There is also a higher likelihood of subtalar nonunion if the two procedures are combined because of differing postoperative protocols: subtalar fusion requires immobilization postoperatively, while arthroplasty requires early motion.

Second, the dislocated ankle joint would require a strong lateral ligament reconstruction to keep the corrected varus from recurring and to maintain the prosthesis within the ankle joint. patient also understood that if the correction were not successful in the first stage, he might require an ankle arthrodesis in the second stage instead of an ankle arthroplasty.

The procedures were scheduled 3.5 months apart with weightbearing commencing at 6 weeks (protected in CAM boot) to prevent disuse osteopenia. A CT scan was required prior to the second surgery to confirm the subtalar fusion to be solid enough to allow hardware removal.


Replacement System

5






Stage 1: Subtalar FusionThrough fluoroscopic images, we can review the key surgical steps with surgeon’s notes:

Deformity Reduction and Fixation

In the first surgical procedure, the deformity was reduced and pinned in a neutral position. The deformity was very rigid, so a smooth wire was inserted and used as a “joystick” to manipulate the ankle to a neutral position (FIGURE 6A).

With the ankle held in neutral, pins were placed, and correction was confirmed with simulated weightbearing (FIGURE 6B). Cement in liquid form was then added to the medial ankle joint and allowed to harden in order to maintain the deformity reduction (FIGURE 6C).

FIGURE 6A,6B,6C: Reduction of deformity with the “joystick”.

6A

6B

6C


Replacement System

6






Deformity Reduction and Fixation...continued

Flat cuts were made at the subtalar joint, removing bone at all three facets (posterior, middle, anterior) to allow maximal bone contact at the subtalar joint while allowing lateral translation of the calcaneus, further reducing varus. The flat cuts incorporated a closing wedge to ensure the heel was reduced. Screws were placed to maintain the correction (FIGURE 6D).

Ligament Reconstruction

The ligament reconstruction was fixed with spiked ligament washers to prevent ligament “creep” at the insertion site. This type of ligament reconstruction must be tight to prevent anterior translation of the talus and varus deformity recurrence. Note the drill hole in the fibula, which required a significant bone bridge at the apex (anterior distal fibula) to prevent bone breakage and tendon graft pullout (FIGURE 6E).

The anatomic insertion points for the washers can be seen in (FIGURE 6F). It is critical to create an anatomic ligament reconstruction with the allograft to maintain alignment.

6D

6E

6F


Replacement System

7






7B

7A

Stage 2: Total ankle replacement surgeryThree and a half months after stage 1 surgery, the total ankle replacement procedure was performed.

The previous hardware was removed, and the INBONE® II footholder was applied, holding the deformity corrected via a lamina spreader (FIGURE 7A). The cement block was removed, although this step is not always required, as the cutting block will cut “around” the cement, allowing joint reduction during preparation.

Sagittal plane fluoroscopy was used to assess bone resection of the tibia and talus. The INBONE® II was an excellent choice in this case, as the patient had a flat-topped talus (FIGURE 7B). A flat-cut talar prosthesis is the only design that will work with this particular anatomy. A chamfer cut prosthesis would notch the talar neck, creating a stress riser that could result in talar neck fracture. Also, the previous ligament reconstruction must be maintained, and a chamfer cut prosthesis would violate the talar neck graft.

The INBONE® II components were placed according to the standard surgical technique. Simulated weight bearing confirmed stability and a balanced ankle joint (FIGURE 7C).

7C


Replacement System

8






Stage 2: Total ankle replacement surgery...continuedSecondary calcaneal assessment via an intraoperative fluoroscopic view (FIGURE 7D) revealed a mild residual heel varus, which required correction (FIGURE 7E). A secondary closing wedge calcaneal osteotomy was performed to align the calcaneus to neutral. No deforming force can be allowed to occur following an ankle replacement of this complexity.

7E

7D


Replacement System

9






Stage 2: Total ankle replacement surgery...continuedIntraoperative flexion and extension range of motion images verified no impingement (FIGURE 7F, 7G). Excellent motion following aggressive gutter debridement can be observed.

7G

7F

Postoperative Care**

Due to edema, before each of the surgical procedures, compression wrap therapy was instituted for one week (Hsu, et.al FAI 35(7): 719-724, 2014). Following each of the procedures, the same compression wrap protocol was instituted postoperatively for 2.5 weeks.

At 2.5 weeks after the first surgery (subtalar arthrodesis and ligament reconstruction), the sutures were removed and compression wrapping was discontinued; the extremity was then casted. The patient was transitioned to a weight bearing CAM boot at 6 weeks postop. At 3 months postoperative, alignment was assessed through gait and standing observation so that the surgeon could determine if supplementary osteotomies would be required at the second stage. CT scan was used to confirm subtalar arthrodesis, and then the second stage surgery was performed.

Following the second surgery (total ankle replacement), physical therapy commenced 2 weeks postoperative, working on passive range of motion. Weightbearing stretch was begun at 4 weeks postoperative because patient had a well-fixed prosthesis without significant supplementary procedures, e.g. osteotomies.

Standing in a CAM boot was implemented at 6 weeks postop with gradual increase in walking from a few steps to return to shoe at 10 weeks.

Physical activities were avoided until 4 months postoperative in order for the bone mass to increase to prevent stress fractures or subsidence at the prosthesis.


Replacement System

10






Patient Outcome

At 1.5 years postoperative, patient was capable of walking in a shoe without pain. He reported feeling balanced and stable, and his swelling was down markedly (FIGURE 8A, 8B, 8C). His range of motion was markedly improved (FIGURE 8D, 8E). Interestingly, his opposite ankle, which appeared fairly normal on his initial assessment, had by that time developed a similar deformity (FIGURE 8C). 8A

8B

8C

8D

8E


Replacement System

11






Patient Outcome...continued

Radiographically, no component subsidence was noted, confirming good resting bone strength to support the prosthesis (FIGURE 9A, 9B, 9C). True ankle range of motion is shown in the flexion/extension radiographs (FIGURE 9D, 9E).

9A 9B

9C

9D

9E

1023 Cherry RoadMemphis, TN 38117800 238 7117901 867 9971www.wright.com

62 Quai Charles de Gaulle69006 LyonFrance+33 (0)4 72 84 10 30www.tornier.com

18 Amor WayLetchworth Garden CityHertfordshire SG6 1UGUnited Kingdom+44 (0)845 833 4435

™ and ® denote Trademarks and Registered Trademarks of Wright Medical Group N.V. or its affiliates. ©2016 Wright Medical Group N.V. or its affiliates. All Rights Reserved.

014599B_23-Aug-2016

CASE STUDY: 2 INBONE Total Ankle Replacement System in a ... · CASE STUDY: 2 INBONE® Total Ankle...

Documents

Transcript of CASE STUDY: 2 INBONE Total Ankle Replacement System in a ... · CASE STUDY: 2 INBONE® Total Ankle...