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Revision surgery must be embraced in this demanding patient population
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Editor’s note: Members of the Patellofemoral Foundation review and add clinical perspective to recently published studies on the causes, prevention and treatment of patellofemoral disorders. The twice monthly blogs are edited by John P. Fulkerson, MD, and can be found on www.healio.com/orthopaedics. To read all the Patellofemoral Update blogs, click here.
Patellofemoral surgery requires careful attention to the overall anatomy of the patient, including both longitudinal limb alignment and soft tissue balance. If the decision is made that bony malalignment is a major contributor to patellar instability, then tibial tubercle transfer osteotomy should be recommended.
Tibial tubercle transfer osteotomy, when properly executed, has the potential to deal with significant patella alta (through patella distalization) and coronal plane deformities identified by aberrant tibial tubercle to trochlear groove distance or excessive Q angle (through medialization). If the medial retinacular soft tissues are evaluated and determined to be lacking, then addressing the medial capsular insufficiency at the time of surgical intervention is warranted.
Recurrent instability
Medial patellofemoral ligament reconstruction (MPFL) is one way to restore medial anatomy. Medial reefing and primary capsular imbrication at the time of tibial tubercle transfer may provide enough medial support in patients who retain robust medial tissues.
Despite the increasing understanding of the need to address both bone and soft tissue stabilizers about the knee, recurrent instability can occur. Orthopaedic surgeons who develop a practice that includes an ever-increasing number of patients who have patellar instability will, at some time, have to deal with recurrent patellar instability.
Images: Spang JT
For the majority of cases, recurrent lateral instability will be a typical presentation, but medial instability due to excessive tibial tubercle medialization or over tensioning of an MPFL reconstruction have to be ruled out. Careful analysis of prior surgical techniques, new imaging and repeat physical examinations are all required if revision surgery is contemplated.
For the majority of patients with recurrent instability, a technical flaw in either the tibial tubercle transfer or an insufficient medial reconstruction (whether from MPFL or medial reefing) can be identified.
Revision tibial tubercle transfer
New imaging can be extremely helpful in the evaluation of the residual effects of prior surgery. In cases of prior tibial tubercle transfer, a CT scan is highly recommended to confirm hardware placement and to critically evaluate tubercle position. A CT scan is mandatory if revision tibial tubercle osteotomy is being contemplated as the prior osteotomy location and the tubercle relationship to the underlying tibia must be completely understood prior to attempting a new osteotomy cut.
In the patient example as shown in Figure 1 and Figure 2, the tibial tubercle transfer as evaluated by the CT scan around the proximal screw location has not resulted in sufficient medialization. In the extended position, the resting leg still shows tremendous lateralization of the patella. At the time of the primary surgery, neither MPFL reconstruction nor medial tissue imbrication was performed.
In planning for an appropriate revision surgery, I find myself adding a formal MPFL reconstruction in almost every case. Simply put, addressing both the underlying bone architecture and reconstructing the medial tissues with a graft allows the surgeon to influence both the distal alignment and the medial constraints at the same time.
In my own practice, I have elected not to pursue trochleoplasty although those familiar with its use in both the primary and the revision setting have reported good clinical results.
For the patient in Figure 3, the CT allowed the team to successfully revise the tibial tubercle transfer. Concern over the quality of the bone did necessitate use of a washer and larger screws, a departure from our normal primary technique. The addition of an MPFL reconstruction addressed inadequate soft tissues medially.
Although every surgeon strives to get it right the first time, revision surgery must be embraced in this demanding patient population. Surgeons should strive to evaluate and re-evaluate candidates for revision surgery. Complete and thorough physical examination should be undertaken at an initial visit and then repeated at a secondary visit after appropriate imaging is ordered. While MRI has great value in any situation, CT scan should be strongly considered as part of a preoperative workup for revision patients.
Lastly, a thorough review of some excellent technique guides for patellofemoral surgery will allow surgeons to eliminate technical errors that may increase the chance of surgical failures.
- References:
- Dejour D, et al. Int Orthop. 2013; doi:10.1007/s00264-012-1746-8.
- Harrison RK, et al. Sports Med Arthrosc. 2013;doi:10.1097/JSA.0b013e31828e88a2.
- Tjoumakaris FP, et al. Am J Sports Med. 2010; doi:10.1177/0363546509357682.
- Tom A, et al. Sports Med Arthrosc. 2007;15(2):68-71.
- Tompkins M, et al. Sports Med Arthrosc. 2012;doi:10.1097/JSA.0b013e31825c74cf.
- For more information:
- Jeffrey T. Spang, MD, can be reached at Department of Orthopedics at the University of North Carolina in Chapel Hill, N.C., USA.
Disclosure: Spang reports no relevant financial disclosures.
Perspective
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David DeJour, MD
When a patellofemoral surgery failure occurs, the first step is to look at the preoperative status with the determination of an objective patellar dislocation (documented), with proper physical examination and adequate preoperative imaging, including standard X-rays and slice imaging.
In the search for causes for the recurrent dislocation, despite possible prior technical faults, it is fundamental to analyze again the instability factors that were not surgically corrected, such as a high-grade trochlear dysplasia (type D), a patella alta (Caton Deschamps index, no trochlea in front of the patella on the CT scan), and an excessive distance between the tibial tuberosity and the trochlear groove or tibial tubercle to trochlear groove (TT-TG) distance (to be measured). Furthermore, the exact location of the medial patellofemoral ligament (MPFL) should be analyzed.
According to these findings, the new procedure must access the factors that are still outside the levels referenced as normal.
In this interesting case, we can notice a high-grade trochlear dysplasia, a patella alta, and the TT-TG has to be measured. The theoretical treatment could be a deepening trochleoplasty, combined with a distalization and an MPFL reconstruction.
The best way to prevent any recurrence and failure is to list the anatomical factors and correct them one by one.
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