INTRODUCTION:. Proper tibial rotation has been cited as an important prerequisite to optimal total knee replacement. The most commonly recognized rotational landmark is the medial 1/3. rd. of the tibial tubercle. The purpose of this study was to quantify the amount of variability this structure has from a common reference as well as to understand the effects of component design when referencing this structure. METHODS:. Subjects were prospectively scanned into a Virtual Bone Database (Stryker Orthopaedics, Mahwah, NJ), which is a collection of body CT scans from subjects collected globally. All CT scans displayed cropped bones were excluded. SOMA™ (Stryker) is a unique tool with the ability to take automated measurements of quantities such as distances and angles on a large number of pre-segmented bone samples which was then to perform calculations represented in this study. Demographic information for each subject was recorded were known. For the analysis, the mechanical axis of the tibia (MAT) was established by connecting the center of the proximal tibia to the center of the ankle. From the MAT, a perpendicular resection plane was made at a distance of 9 mm from the most proximal portion of the lateral condyle. This plane was then used as a virtual resection plane to establish the points for the remaining structures which was the medial 1/3. rd. of the tibial tubercle and the posterior notch of the PCL insertion. The following axes were identified: 3TT (line between the medial 1/3. rd. of the tibial tubercle and the posterior notch of the tibia); 3CTT (line between the medial 1/3. rd. of the tibial tubercle and the center of the tibia); and the posterior axis of the tibia (line connecting the two most posterior points of the tibia at the virtual resection plane). Measurements made were the angle of the 3TT Line to the posterior axis and the angle of the 3CTT Line to the posterior axis. RESULTS:. CT Scans of the Left Knees (n = 524), Right Knees (n = 527), and combined left/right knee (n = 1051) were collected for this study. The mean 3TT angle for the left knee was 74.6° ± 3.0° (Range: 60.2°–84.8°) and right knee was 74.5° ± 3.0° (Range: 65.1°– 85.1°). The combined (left/right) angle was 74.5° ± 3.0° (Range: 60.2°–85.1°). The mean 3CTT angle for the left knee was 71.2° ± 3.6° (Range: 57.6°–83.2°) and right knee was 71.1° ± 3.5° (Range: 61.4°–82.3°). The combined (left/right) angle was 71.1° ± 3.6° (Range: 57.6°–83.2°). The two methods resulted in a 3.4° difference, with the 3TT reference being more externally rotated. DISCUSSION:. The tibial tubercle is a common landmark used to set the rotation of the tibial component and utilizing the posterior aspect of the tibia provides a common reference point to establish variations that could exist with this landmark. The amount of variation of the tibial tubercle can vary by over 25 degrees. Asymmetric baseplates will set rotation based on tibial coverage so variation from the tubercle is can not be accommodated if the surgeon routinely uses this as a landmark. Symmetric baseplates can provide more options for rotational placement

Safely obtaining adequate exposure is an integral step in successfully performing a Total Knee Arthroplasty. In this study, we look at approaching the valgus knee through a lateral arthrotomy and tibial tubercle osteotomy. 20 knees in 19 consecutive patients with valgus deformities are included in this study (2006 to 2010). LCS mobile bearing prostheses were implanted by a single senior surgeon (GF). Navigation was used for all the knees. The knee is approached throught a skin incision 5–10mm more lateral than the standard midline incision. The lateral arthrotomy is made to Gerdy's tubercle 7–10cm distal to Tibial Tendon insertion. 7cm long and 2cm wide osteotomy is performed. Richards staples are used to fix the osteotomy once the prosthesis is fixed. All patients were followed up by the operating surgeon. All osteotomies united. 2 postoperative complications were encountered during follow up. One patient had a postoperative haematoma that was washed out. A second patient had a fall 6/52 post-op and sustained a minimally displaced fracture at the navigation pin site (Tibia). This was treated in a cylinder cast and went onto full union. Our technique of lateral arthrotomy and TTO in the valgus knee is safe and predictable. It delivers wider exposure, facilitates soft tissue management, preserves viability of the extensor mechanism and allows some movement of the tibial tubercle for improved patella tracking. We recommend planning this procedure preoperatively for best results

We identified 26 tibial tubercle osteotomies (TTOs) performed in 23 revision knee arthroplasties between 2009 and 2013. Average age at last operation was 66 (33–92). Mean follow-up period was 14 months (3–33). Eleven TTOs were performed in 10 knees for single stage revisions and 15 TTOs were performed in 13 knees for 2 stage revisions in the setting of deep infection. In this infected subset 11 patients had a TTO performed at the first stage. This osteotomy was left unfixed to avoid leaving metalwork in a potentially contaminated wound, reopened, and then definitively secured with screws at the second stage. Our technique involves fashioning a long 7×1cm tibial tuberosity osteotomy without a proximal step-cut. All osteotomies united with no fractures. Minor proximal migration was noted in one case associated with screw loosening. There was no proximal migration noted in the 2 stage cases where the osteotomy had been left initially unfixed. There were no extensor lags. We conclude that TTO is a safe and reproducible procedure when adequate exposure cannot be obtained in revision knee arthroplasty. In 2 stage revisions sequential osteotomies does not decrease union rates and leaving the osteotomy unfixed after the first stage does not cause any issues

Patients with recurrent patella instability, who have an abnormal patellofemoral alignment (patella height or tibial tubercle-trochlear groove (TTTG) distance), benefit from tibial tubercle transfer along with medial patellofemoral ligament (MPFL) reconstruction. Between July 2008 and April 2013, 18 patients (21 knees) with recurrent patellar instability underwent combined MPFL reconstruction and tibial tubercle transfer. All patients had abnormal patellofemoral alignment in addition to MPFL insufficiency. 15 patients (16 knees) with a mean age of 24 years (16–41) had a mean follow up of 26 months (6–55). We assessed the outcome using KOOS, KUJALA, activity level and patient satisfaction scores. All patients had a stable patella. There was a significant improvement in outcome scores in 12 out of 15 patients. At final follow up KOOS score had improved from 68.25(44 to 93.9) to 77.05(48.8 to 96.4) and KUJALA score had improved from 63.3(41–88) to 78.06 (45 to 99). 9 patients showed excellent results and achieved at least a pre-injury level of activity. 4 of these had activity level better then preoperative level. 6 patients had a lower activity level than pre-injury (1 – ongoing physiotherapy, 1 – because of lack of confidence, and 4 – Life style modification). 14 patients were satisfied and happy to recommend this procedure. There were 3 postop complications, with 2 cases of stiffness and 1 case of non-union of the tibial tuberosity. Our prospective study has shown that restoration of tibial tubercle-trochlear groove index, Patella height and Medial Patellofemoral Ligament reconstruction yields good results in carefully selected patients

Aim. We report the results of a modified Fulkerson technique of antero-medialisation of the tibial tubercle, combined with microfracture or abrasion arthroplasty in patients under 60 with patello-femoral osteoarthritis. Methods. All patients operated between September 1992 and October 2007 were reviewed by an independent observer in clinic or by postal questionnaire, using the Oxford Knee Score, Melbourne Patella Score and a Satisfaction Score. Only patients with Outerbridge Grade 3-4 osteoarthritis of the patello-femoral joint were included. They were assessed pre-operatively with plain x-rays, MRI scans (as well as tracking scans in the last 10 years) and arthroscopically. All patients with tracking scans showed lateral subluxation of the patella. The surgical procedure was a modification of Fulkerson's tibial tubercle osteotomy, with an advancement of 1-1.5cms and a medialisation of 1.5cms. The exposed bone of the patella and trochlea was drilled in the early cases and in the later cases an arthroscopic microfracture or abrasion using a power burr was carried out. Results. Between September 1992 and October 2007, 103 procedures were carried out in 84 patients, 19 patients having staged bilateral procedures. The mean follow-up was 84 months (range 24-204 months). The mean age was 45 (range 26-59) and the female to male ratio was 7.6:1. 70 patients were reviewed (follow-up rate of 82%). The mean Oxford Knee Score was 18.5 pre-operatively (range 3-32) and 34.3 post-operatively (range 11-47). The Melbourne Patella Score was 9.6 pre-operatively (range 3-30) and 20 post-operatively (range 11-30). Patient Satisfaction Scores were excellent (54%), good (29%), fair (8.5%) and poor (8.5%). 4 knees in 3 patients were converted to a patello-femoral arthroplasty, giving a 10 year survival rate of 96.1%. Conclusion. This procedure offers an alternative to patello-femoral arthroplasty for younger patients with isolated patello-femoral arthritis

INTRODUCTION. Conventional surgical exposures are usually inadequate for 2-stage revision knee replacement ofinfected implants. Reduced range of motion, extensor mechanism stiffness, peripatellar contracture and soft tissue scarring make patellar eversion difficult and forced eversion places the integrity of the extensor mechanism at risk. On the contrary, a wide exposure is fundamental to allow complete cement spacer removal, soft tissue balancing, management of bone loss and reimplantation without damaging periarticular soft tissues. OBJECTIVES. To compare the long-term clinical, functional and radiographic results and the reinfection rate of the quadriceps snip approach and the tibial tubercle osteotomy in 2-stage revision knee replacement performed for septic loosening of the primary implant. METHODS. In our department, 87 patients had a 2 stage revision knee replacement for septic loosening of the primary implant between 1996 and 2008. In all patients, first stage consisted of primary implant removal, extensive soft tissue debridement and positioning of a static antibiotic loaded cement spacer. The timing for reimplantation was decided basing on negative clinical and laboratory (ESR, CRP) signs and negative Leukoscan results. For reimplantation, a quadriceps snip was used in patients with an intraoperative flexion >90° (Group A) while a tibial tubercle osteotomy (Group B) was used in patients with an intraoperative flexion <90°. RESULTS. At observation point, 4 patients died for reasons unrelated to surgery, leaving 42 patients in Group A and 41 in Group B. We had a total amount of 10 recurrent infections (11%) after reimplantation, 7 patients in Group A and 3 patients in Group B (p<0.005). Patients with a reinfection in Group A were treated with a knee fusion in 4 cases, a rerevision in 2 cases and an amputation above the knee in 1 case, while all those with a reinfection in Group B had a knee fusion. According to HSS score, 11 patients were rated as Excelent/Good in Group A and 9 patients in Group B (p=n.s.). Three patients had a major complication in Group A and 0 patients in Group B (p=0.005). No differences were found between the two groups regarding range of motion and subjective satisfaction. CONCLUSION. Tibial tubercle osteotomy is a safe procedure to obtain a wide exposure in 2-stage revision knee replacement performed for septic loosening of the primary implant and it is effective in reducing reinfection rate without compromising clinical results and range of motion

Background. Accurate implant positioning is of supreme importance in total knee replacement (TKR). The rotational profile of the femoral and tibial components can affect outcomes, and the aim is to achieve coronal conformity with parallelism between the medio-lateral axes of the femur and tibia. Aims. The aim of this study is to determine the accuracy of implant rotation in total knee replacement. Methods. Intra-operatively, the trans-epicondylar axis of the femur (TEA) and Whiteside's line were used as the reference points, aiming to externally rotate the femoral component by 1 degree. The medial third of the tibial tuberosity was used as the anatomical reference point, aiming to reproduce the rotation of the native tibia. Pre-and post-operative CT scans were reviewed. The difference in femoral rotation was calculated by determining the femoral posterior condylar axis (PCA) of the native femur pre-operatively and the implant post-operatively. Tibial rotational difference was calculated between the native tibial posterior condylar axis and tibial baseplate. Results. Pre and post-operative CT scans of 41 knees in 31 patients were analysed. All surgeries were carried out by a single surgeon using the same implant. The mean difference in rotation of the femur post-operatively was 1.2 degrees external rotation (ER), range −4.7 to 6.9 degrees ER. 83% of femoral components were within 3 degrees of the target rotation. Mean difference in tibial rotation was −3.8 degrees ER, range −11.1 to 12.4 ER. Only 39% of tibial components were within 3 degrees of the target rotation. A line perpendicular to the midpoint of the tibial PCA was actually medial to the tibial tubercle in 33 knees, and only corresponded to the medial 1/3 of the tibial tubercle in 8 of 41 knees. Conclusions. Femoral component rotation is seen to be more accurate than tibial in this group. It may be that the anatomical landmarks used intra-operatively to judge tibial rotation are more difficult to accurately identify. Posterior landmarks are difficult to locate in vivo. This study would suggest that using the anterior anatomical landmark of the medial 1/3 of the tibial tubercle does not allow accurate reproduction of tibial rotation in total knee replacement

Introduction. Post-operative clinical outcomes of TKA are dependent on a multitude of surgical and patient-specific factors. Malrotation of the femoral and/or tibial component is associated with pain, accelerated wear of the tibial insert, joint instability, and unfavorable patellar tracking and dislocation. Using the transepicondylar axis to guide implantation of the femoral component is considered to be an accurate anatomical reference and is widely used. However, no gold standard currently exists with respect to ensuring optimal rotation of the tibial tray. Literature has suggested that implantation methods, which reference the tibial tubercle, reduce positioning outliers with more consistency than other anatomical landmarks. Therefore, the purpose of this evaluation is to use data collected from intraoperative sensors to assess the true rotational accuracy of using the mid-medial third of the tibial tubercle in 98 TKAs. Methods. The data for this evaluation was retrieved from 98 consecutive patients who underwent primary TKA from the same highly experienced surgeon. Femoral component rotation was verified in every case via the use of the Whiteside line, referencing the transepicondylar axis, and confirming appropriate patellar tracking. Tibial tray rotation was initially established by location of the mid-medial third of the tibial tubercle. Rotational adjustments of the tibial tray were evaluated in real-time, as the surgeon corrected any tibiofemoral incongruency and tray malpositioning. The initial and final angles of tibial tray rotation were captured with intraoperative video feed, and recorded. A z-test of differences between pre- and post-rotational correction was performed to assess the statistical significance of malrotation present in this cohort. Results. All patients in this study received a primary TKA, using the mid-medial third of the tibial tubercle to dictate tibial tray rotation. After the sensor-equipped tibial insert was implanted, it was shown that 63.1% of patients exhibited unfavorable rotation. Of those patients, 70% were shown to have internal rotation; 30% were shown to have external rotation. The average malrotation of the tibial tray deviated from a neutral position by 6.3° ± 4.3°, ranging from 0.5° to 19.2°. The z-test of differences yielded a p-value <0.0001, indicating that the proportion of malrotation was statistically significant. The 95% confidence interval of this cohort was calculated to be between 44.8% and 71.8% of malrotation. Discussion. Malrotation in TKA isassociated with poor clinical outcomes. While no gold standard anatomic landmark currently exists for positioning the tibial tray, the mid-medial third of the tibial tubercle is widely used as a reference. However, the data from this evaluation demonstrates that, not only is this landmark insufficient for establishing optimal rotation (p < 0.0001), but that it had guided the surgeon to an average of 6.3° outside of the optimized implant congruency zone. The large confidence interval indicates that the rotational alignment of the tibial tray—based on the location of the mid-medial third of the tibial tubercle—is not only inaccurate, but also highly variable. Based on this intraoperative sensor data, we suggest that care should be taken when utilizing the tibial tubercle as the sole rotational landmark for the tibial tray

Achievement of adequate exposure in revision total knee arthroplasty is critical as it reduces the surgical time, enhances the ability for both component removal and reconstruction, and avoids devastating complications such as extensor mechanism disruption. However, this can be challenging as prior multiple surgeries and limited mobility contribute to a loss of tissue elasticity, thickened capsular envelope, and peri-articular soft tissue adhesions. A thorough pre-operative assessment of a patient's past surgical history, comorbidities, pre-operative radiographs (i.e. the presence of severe patella baja), and physical examination including range of motion, prior incisions, and soft tissue pliability are useful in determining the appropriate surgical techniques necessary for a successful revision. A systematic approach to the ankylosed knee is critical. Most techniques are geared towards mobilization of the extensor mechanism to safely displace the patella for component exposure. The initial exposure should consist of a long skin incision, a subperiosteal medial release, and debridement of suprapatellar, medial, and lateral adhesions to the femoral condyles. A lateral capsular release can prove helpful in further mobilization of the extensor mechanism. When performing a medial parapatellar arthrotomy it's important to keep in mind further extensile exposure techniques that may be required. For example, the arthrotomy should not extend proximally into the vastus intermedius or rectus femoris in the event that a quadriceps snip technique is to be used as this can compromise the ability to repair this exposure. Despite a large exposure and release of adhesions, sometimes the extensor mechanism remains at risk of rupture and adequate visualization cannot be obtained. In this event, extensile exposures such as a quadriceps snip, quadriceps turndown or tibial tubercle osteotomy are considered. The location of the patella often dictates the best exposure option as severe patella baja may not be overcome with a proximally based release. The quadriceps snip is most commonly used and provides improved exposure without the necessity of modifying the patient's post-operative rehabilitation. In addition, it can be extended to a quadriceps turndown which vastly improves visualization, but at the expense of needing to immobilise the knee post-operatively. A tibial tubercle osteotomy can also be used and provides excellent exposure especially in the case of severe patella baja or when removal of a cemented tibial stem is required. It preserves the extensor muscles, but risks include increased post-operative wound drainage due to limited soft tissue coverage, failure of fixation, or fracture of the tibial tubercle fragment or tibial shaft. Exposure in revision total knee arthroplasty is critical. Fortunately, this can be reliably achieved with a systematic approach to the knee and through the use of several extensile exposures at the surgeon's discretion

Recurrent patellar instability is a common problem and there are multiple demographic and pathoanatomic risk factors that predispose patients to dislocating their patella. The most common of these is trochlear dysplasia. In cases of severe trochlear dysplasia associated with patellar instability, a sulcus deepening trochleoplasty combined with a medial patellofemoral ligament reconstruction (MPFLR) may be indicated. Unaddressed trochlear pathology has been associated with failure and poor post-operative outcomes after stabilization. The purpose of this study is to report the clinical outcome of patients having undergone a trochleoplasty and MPFLR for recurrent lateral patellofemoral instability in the setting of high-grade trochlear dysplasia at a mean of 2 years follow-up. A prospectively collected database was used to identify 46 patients (14 bilateral) who underwent a combined primary MPFLR and trochleoplasty for recurrent patellar instability with high-grade trochlear dysplasia between August 2013 and July 2021. A single surgeon performed a thin flap trochleoplasty using a lateral para-patellar approach with lateral retinaculum lengthening in all 60 cases. A tibial tubercle osteotomy (TTO) was performed concomitantly in seven knees (11.7%) and the MPFLR was performed with a gracilis tendon autograft in 22%, an allograft tendon in 27% and a quadriceps tendon autograft in 57% of cases. Patients were assessed post-operatively at three weeks and three, six, 12 and 24 months. The primary outcome was the Banff Patellar Instability Instrument 2.0 (BPII 2.0) and secondary outcomes were incidence of recurrent instability, complications and reoperations. The mean age was 22.2 years (range, 13 to 45), 76.7% of patients were female, the mean BMI was 25.03 and the prevalence of a positive Beighton score (>4/9) was 40%. The mean follow-up was 24.3 (range, 6 to 67.7) months and only one patient was lost to follow-up before one year post-operatively. The BPII 2.0 improved significantly from a mean of 27.3 pre-operatively to 61.1 at six months (p < 0 .01) and further slight improvement to a mean of 62.1 at 12 months and 65.6 at 24 months post-operatively. Only one patient (1.6%) experienced a single event of subluxation without frank dislocation at nine months. There were three reoperations (5%): one for removal of the TTO screws and prominent chondral nail, one for second-look arthroscopy for persistent J-sign and one for mechanical symptoms associated with overgrowth of a lateral condyle cartilage repair with a bioscaffold. There were no other complications. In this patient cohort, combined MPFLR and trochleoplasty for recurrent patellar instability with severe trochlear dysplasia led to significant improvement of patient reported outcome scores and no recurrence of patellar dislocation at a mean of 2 years. Furthermore, in this series the procedure demonstrated a low rate (5%) of complications and reoperations

Following a careful in-depth preoperative plan for revision TKA, the first surgical step is adequate exposure. It is crucial to plan your exposure for all contingencies. Prior incisions have tremendous implications and care must be taken to consider their impact. Due to the medially based vascular supply to the skin and superficial tissues about the knee, consideration for use of the most LATERAL incision should be made. It is essential to avoid the development of flaps which may compromise the skin and soft tissue which can have profound implications. Exposure options can be broken down into either PROXIMALLY based techniques or DISTALLY based options. The proximal based techniques involve a medial parapatella arthrotomy followed by the establishment of medial and lateral gutters. An assessment of the ability to evert or subluxate the patella should be made. Care must be taken to protect the insertion of the patella tendon into the tibial tubercle. If the patella is unable to be mobilised, then extension of arthrotomy proximal is performed. If this is not adequate, then consider inside out lateral release. If still unable to mobilise, then a QUAD SNIP is performed. In rare instances, you can connect the lateral release with quad snip resulting in a V-Y quadplasty, which results in excellent exposure. Another option is to employ DISTALLY based techniques such as the tibial tubercle osteotomy technique described by Whiteside. A roughly 8cm osteotomy segment with distal bevel is performed. The osteotomy must be at least 1.5–2cm thick: too thin and risk of fracture increases. This approach leaves the lateral soft tissues intact and then a “greenstick” of the lateral cortex is performed with eversion of patella and the lateral sleeve of tissue. This technique is excellent for not only exposure but also in instances where tibial cement or a cementless tibial stem needs to be removed. Closure is accomplished with wires either through the canal or around the posterior cortex of the tibia

Like all surgery, if you can see it, you can usually get the job done. This is especially true for extracting well-fixed components, as iatrogenic bone loss is a serious consideration regarding the reconstruction challenge. While reasons for revision are varied, several general principles are useful to consider during the pre and peri-operative course. Pre-operatively, forewarned is forearmed. Certain factors pre-operatively can suggest the degree of operative difficulty regarding exposure. Revisions for stiffness obviously would suggest difficulty with exposure. Revisions in knees with patellar baja are almost always challenging as the patella is difficult to evert. When revising infected knees, an exuberant synovial response can result in beefy, friable synovium that has a volume effect with decreased tissue compliance. Further, the hyperemic friable tissue bleeds easily, even with tourniquet, and is difficult to anticoagulate. Peri-operatively, the general principles to consider are as follows: 1) Don't rush exposure. Good exposure is the result of a series of deliberate and sequential steps that safely reduce tissue volume and improvement in tissue compliance. These steps include in almost all cases: a. Extend the incision as necessary, there is no call for minimally invasive revision knee surgery; b. Tenolysis of the patellar tendon; c. Clearing of the medial and lateral gutter; d. Clearing of the flexion space; e. Clearing of quadriceps adhesions. 2) Protect the extensor mechanism, above all else. Carefully monitor the insertion of the patellar tendon when beginning to flex the knee. If an avulsion begins, back off flexion and spend more time on clearing of scar tissue, as above. If still unsuccessful, then extensile exposure should be considered, such as a quadriceps snip. Be especially careful when osteolysis is present around the tibial tubercle. 3) The most difficult area to of the knee to expose in revision surgery is the posterior lateral corner, resulting in difficulty in exposing the posterior lateral femur and the posterior corner of the tibial component. Extensile exposures do not necessarily result in complete exposure of these regions. Redoubling efforts to remove scar tissue is often more successful. Bovie dissection of soft tissue on the proximal medial tibia can assist, with extension back to the semimembranosus insertion sometimes being necessary. While adequate exposure can result because of the increased ability to externally rotate the tibia, this exposure can also destabilise the medial side of the knee, sometimes resulting in the need to add constraint. The pros and cons need to be considered on a case-by-case basis. 4) Be judicious in the utilization of extensile exposures, and choose the exposure technique best suited for the situation. If the patellar tendon is normal, consider a simple quadriceps snip. If the knee is particularly stiff or the tibial tubercle or patellar tendon insertion is in jeopardy, then the snip can be extended into a V-Y turndown. If the patellar tendon is contracted resulting in patellar baja, then a tibial tubercle osteotomy (TTO) can be considered. Careful removal of tissue in scar tissue, as above, allows for relative external rotation of the tibia on the femur that translates the patella laterally, reducing the need for TTO. TTO can also be effective when approaching a cemented tibial stem

Exposure for revision knee requires using the previous incision, employing the “quad snip”, the “Banana Peel”, or the tubercle osteotomy. The “quad snip” is a 45-degree incision of the proximal extensor mechanism that helps protect the distal insertion on the tubercle. The “banana peel,” is my exposure of choice and has been used extensively for revision total knee arthroplasty (TKA) for more than 20 years in my community. We retrospectively reviewed use of this technique in a cohort of 100 consecutive patients who underwent tibial-femoral stemmed revision TKA. The technique involves peeling the patella tendon as a sleeve off the tibia, leaving the extensor mechanism intact with a lateral hinge of soft tissue. A quadriceps “snip” must be done proximally to avoid excessive tension. No patient has ever reported disruption of the extensor mechanism or decreased ability to extend the operative knee. With a mean Knee Society score of 176 (range, 95–200). Post-operative motion was 106 degrees. No patient reported pain over the tibial tubercle. The “banana peel” technique for exposing the knee during the revision TKA is a safe method that can be used along with a proximal quadriceps snip and does not violate the extensor mechanism, maintaining continuity of the knee extensors. As a last resort, tibial tubercle osteotomy as described by Whiteside, is preferred for revising porous coated stemmed tibial components and is repaired with cerclage wire or cables. Keep the osteotomy fragment at least 8–10cm long leaving a lateral soft tissue attachment

Introduction. Optimized tibial tray rotation during a total knee replacement (TKR) is critical for tibiofemoral congruency through full range of motion, as it affects soft tissue tension, stability and patellar tracking. Surgeons commonly reference the tibial tubercle, or the “floating tibial tray,” while testing the knee in flexion and extension. Utilization of embedded sensors may enable the surgeon to more accurately assess tibiofemoral contact points during surgery. Methods. The malrotation of the tibiofemoral congruency when utilizing the mid to medial 1/3 of the tibial tubercle for tibial rotation was evaluated in 50 posterior cruciate ligament-retaining TKRs performed by an experienced, high-volume surgeon. Sensors were embedded in the tibial trials; the rotation of the tibial tray was defined, and the femoral contact points in each compartment were captured. The surgical procedure was performed to size and then appropriately rotate the tibial tray. The anterior medial tray was pinned to control anterior-posterior and medio-lateral displacement, and allow internal and external rotation of the tray. With the capsule closed and patella reduced, the knee was reduced with trial implants. The femoral contact points and medial-lateral soft tissue tension were documented. Patellar tracking and changes in soft tissue tension were also documented. Results. In 60% (n = 30/50) of cases, further external rotation (average 5 degrees) was required. No further rotation was required in 10% (n = 5/50), and 30% (n = 15/50) required further internal rotation for optimized congruency. Patellar tracking and changes in soft tissue tension based on rotation showed parallel center of load in medio-lateral compartments and equalized intercompartment pressures resulting in optimized balance of the knee. Conclusions. Utilizing the tibial tubercle for optimized tibial tray rotation and femoral congruency was only adequate in 10% of cases. The use of sensors to define the femoral contact points on the tibia enabled the surgeon to adjust the tibial tray to optimize tibiofemoral congruency. Mal-rotated trays negatively affected soft tissue tension and patellar tracking

Introduction:. Proper rotational alignment of the tibial component is a critical factor in the outcome of total knee arthroplasty (TKA), and misalignment has been implicated as a major contributing factor to several mechanisms of TKA failure. In this study we examine the relationship between bony and soft tissue tibial landmarks against the knee motion axis (plane that best approximates tibiofemoral motion through range of motion). Methods:. The kinematic motions of 16 fresh-frozen lower limb specimens were analyzed in simulated lunging and squatting. All the tendons of the quadriceps and hamstrings were independently loaded to simulate a lunging or squatting maneuver. All specimens underwent CT scan and the 3D position of the knee was virtually reconstructed. Ten anatomic axes were identified using both the intact tibia and the resected tibial surface. Two axes were normal vectors to either the medial-lateral plateau center or the posterior tibial surface. Seven axes were defined between the tibial tubercle (the most prominent point, center of the tubercle, or medial third of the tubercle) and soft tissue landmarks of the tibia (the medial insertion of the patellar tendon, the center of the PCL and ACL, and the tibial spines). The last axis was the Knee Motion Axis (KMA), which was defined as the longitudinal axis of the femur from 30 to 90 degrees of flexion. Results:. The closest approximation of the KMA was provided by the axis from the PCL to Medial Tibial Spine Axis, which was internally rotated 1.9 ± 7.6 degrees (Table – 1). The closest axis to the KMA in external rotation was the axis from the tibial plateau center to the medial third of the tibial tubercle, which was externally rotated 2.8 ± 4.3 degrees. The most precisely located constant axis was from the center of the tibia to the center of the tibial tubercle, which was externally rotated by 14.9 ± 3.7 degrees. Conclusions:. The line connecting the center of the PCL and the mid-point between the medial and lateral tibial spines was the closest to the functional tibial rotation. Though no individual landmark exactly correlated with the KMA in all knees, we found that the average anteroposterior motion of the femur with the tibia from 30 to 90 degrees of the femur could be consistently described by these landmarks, and that the addition of soft-tissue landmarks to prior bony topography can provide reliable indications to the location of the KMA

The battle of revision TKA is won or lost with safe, effective, and minimally bony-destructive implant removal, protecting all ligamentous stabilisers of the knee and, most importantly, the extensor mechanism. For exposure, incisions should be long and generous to allow adequate access. A standard medial parapatellar capsular arthrotomy is preferred. A synovectomy is performed followed by debridement of all scar tissue, especially in the medial and lateral gutters. All peripatellar scar tissue is excised followed by release of scar tissue within the patellar tendon, allowing for displacement or everting of the patella. As patellar tendon avulsion at any time of knee surgery yields disastrous results, the surgeon should be continuously evaluating the patellar tendon integrity, especially while displacing/everting the patella and bringing the knee into flexion. If displacement/eversion is difficult, consider rectis-snip, V-Y quadricepsplasty, or tibial tubercle osteotomy. The long-held requisite for patellar eversion prior to component removal is inaccurate. In most cases simple lateral patellar subluxation will provide adequate exposure. If a modular tibial system is involved, removal of the tibial polyethylene will decompress the knee, allowing for easier access to patellar, femoral, and tibial components. For patellar component removal, first identify the border of the patella, then carefully clean and debride the interface, preferably with electrocautery. If the tibial component is cemented all-polyethylene, remove using an oscillating saw at the prosthetic-bone interface. Debride the remaining cement with hand tools, ultrasonic tools, or burrs. Remove the remaining peg using a low-speed burr. If the tibial component is metal-backed, then utilise a thin saw blade or reciprocating saw to negotiate the undersurface of the component between the pegs. If pegs are peripherally located, cut with a diamond disc circular cutting tool. Use a trephine to remove the pegs. For femoral component removal, identify the prosthetic-bone/prosthetic-cement interface then remove soft tissue from the interface, preferably with electrocautery. Disrupt the interface around all aspects of the component, using any of following: Gigli saw for cementless components only, micro saw, standard oscillating saw, reciprocating saw, a series of thin osteotomes, or ultrasonic equipment. If the femoral component is stemmed, remove the component in two segments using an appropriate screwdriver to remove the screw locking the stem to the component. Remove the femoral component with a retrodriver or femoral component extractor. Debride cement with hand tools or burr, using care to avoid bone fracture. If a stem is present, then remove with the appropriate extraction device. If “mismatch” exists, where femoral (or likewise, tibial) boss is smaller in diameter than the stem, creating a cement block prohibiting stem removal, remove the cement with hand tools or burr. If the stem is cemented, use hand tools, ultrasonic tools, or a burr to debride the cement. Curette and clean the canals. For tibial component removal, disrupt the prosthetic-cement/prosthetic-bone interface using an oscillating or reciprocating saw. Gently remove the tibial component with a retrodriver or tibial extractor. If stem extensions are utilised, disengage and debride all proximal cement prior to removing the stem. If stem is present, then remove stem with appropriate extraction device. If stem is grit-blasted and well-fixed, create 8mm burr holes 1.5 to 2.5cm distal to tibial tray on medial aspect and a small divot using burr, then drive implant proximally with Anspach punch. Alternatively, a tibial tubercle osteotomy may be performed. If the stem is cemented, use hand tools, ultrasonic tools or burr to debride cement

After over 4 decades of experience with total knee arthroplasty, many lessons have been learned regarding surgical technique. These include exposure issues, alignment methods, bone preparation, correction of deformity, implantation techniques and wound closure. Where is the proper placement of the skin incision relative to the tibial tubercle? How does one safely evert the patella in the obese or ankylosed knee? Can a tibial tubercle osteotomy be avoided in the ankylosed knee? How does one protect the patellar tendon insertion from avulsing? How do you protect the soft tissues from debris and contamination and minimise the potential for infection? Can exposure be maintained if there are few surgical assistants? How do you find the lateral inferior genicular vessels and minimise postoperative bleeding? How do you know where to enter the intramedullary femoral canal for placement of the distal femoral alignment device? How can you avoid notching the anterior femoral cortex when in-between sizes or there is a pre-existing dysplastic trochlea? How can you correct a varus deformity without performing a formal MCL release? An inverted cruciform lateral retinacular release effectively corrects a severe valgus deformity and avoids the need for an LCL release. Trimming the posterior femoral condyles and removing posterior osteophytes is best accomplished using a trial femoral component as a template. Zone 4 femoral bone-cement radiolucencies can be minimised using the “smear” technique. The best indicator of potential postoperative flexion is not preoperative flexion but is intraoperative flexion against gravity measured after capsular closure

Introduction. Poor clinical outcomes following total knee arthroplasty (TKA) can be related to improper alignment of the components. The main challenge is the variability in biomechanical references, especially in cases of severe deformity or dysplasia, and in determining the surgical landmarks intraoperatively. An intraoperative imaging tool can be very useful to assess the alignments when there is still a chance for correction. We investigated, on cadaveric specimens, the accuracy of using iso-centric (ISO-C) imaging (that reconstructs 3D from multiple 2D fluoroscopic images) for this purpose. Methods. Six fresh frozen cadaveric knees were implanted with a standard TKA system and imaged using an ISO-C 3D C-arm (Arcadis Orbic ISO-C). Each knee was scanned two times with the Iso-C scanner and with appropriate image settings to capture the transepicondylar axis (TEA) and the tibial tubercle individually. A CT scan of each specimen was acquired as the reference for comparison. The ISO-C 3D reconstructed volumes were analyzed on the C-arm. For the CT images, the 3D data were processed in Analyze software with the same objective. The surgical and clinical TEA was determined by moving and rotating an oblique cutting plane (Figure 1a:CT and 1c:ISO-C). This oblique slice was then moved distally to picture the femoral pegs (Figure 1b:CT and 1d:ISO-C). The angle between these two references (angle α in Figure 1) defined the rotational alignment. For the tibial component, the first cutting slice was oriented parallel to the component. A second slice was defined just distal to the component, and then moved distally to find the tibial tubercle in the third slice. The orientation of the tibial component was determined by fitting a rectangular box to the component boundary (Figure 2a:CT and 2d:ISO-C). The bone orientation was defined by a line connecting the centroid of a polygon drawn over the boundary of the cortical bone (Figure 2b:CT and 2e:ISO-C) to the medial third of the tibial tubercle (Figure 2c:CT and 2f:ISO-C). Measurements were repeated five times, the overall accuracies determined in comparison to CT, and the correlation between the ISO-C and CT determined by the Spearman rank (P<0.05). Results. Correlation between the ISO-C and CT measures of the femoral and tibial alignments was statistically significant (P=0.005 and P=0.018) with corresponding correlation coefficients of 0.94 and 0.89 (Figure 3). The overall accuracies calculated for all of the specimens were 0.3°± 0.8° for the femoral component, and 0°±1.4° for the tibial component. The calculated effective doses for the ISO-C imaging protocol of the femoral and tibial components were 0.005 mSv and 0.025 mSv respectively. Discussion. This study showed that it is feasible to use ISO-C imaging for assessing the alignment of TKA components with acceptable accuracy both intraoperatively and postoperatively. The intraoperative assessment of ISO-C can help improve the outcome of knee arthroplasty and avoid early revisions because of complications related to component alignments. Results showed that it is also possible to use the ISO-C imaging as a safer modality (i.e. less radiation dose) for investigating links between proper component alignment and post-arthroplasty complications

“The shortest distance between two points is a straight line.” This explains many cases of patellar maltracking, when the patellar track is visualised in three dimensions. The three-dimensional view means that rotation of the tibia and femur during flexion and extension, as well as rotational positioning of the tibial and femoral components are extremely important. As the extensor is loaded, the patella tends to “center” itself between the patellar tendon and the quadriceps muscle. The patella is most likely to track in the trochlear groove IF THE GROOVE is situated where the patella is driven by the extensor mechanism: along the shortest track from origin to insertion. Attempts to constrain the patella in the trochlear groove, if it lies outside that track, are usually unsuccessful. Physiologic mechanisms for tibial-femoral rotation that benefit patellar tracking (“screw home” and “asymmetric femoral roll-back”) are not generally reproduced. Practical Point. A patellofemoral radiograph that shows the tibial tubercle, illustrates how the tubercle, and with it the patellar tendon and patella itself, are all in line with the femoral trochlea. To accomplish this with a TKA, the femoral component is best rotated to the transepicondylar axis (TEA) and the tibial component to the tubercle. In this way, when the femoral component sits in its designated location on the tibial polyethylene, the trochlear groove will be ideally situated to “receive” the patella. Knee Mechanics. Six “degrees of freedom” refers to translation and rotation on three axes (x,y,z). This also describes how arthroplasty components can be positioned at surgery. The significant positions of tibial, femoral and patellar components are: 1. Internal-external rotation (around y-axis) and 2. Varus-valgus rotation (around z axis). 3. Medial-lateral translation (on x-axis). The other positional variables are less important for patella tracking. Biomechanical analyses of knee function are often broken down into: i. Extensor power analysis (y-z or sagittal plane) and ii. Tracking (x-y or frontal plane). These must be integrated to include the effects of rotation and to better understand patellar tracking. Effect of Valgus. Frontal plane alignment is important but less likely to reach pathological significance for patellar tracking than rotational malposition clinically. For example if a typical tibia is cut in 5 degrees of unintended mechanical valgus, this will displace the foot about 5 cm laterally but the tibial tubercle only 8 mm laterally. An excessively valgus tibial cut will not displace the tubercle and the patella as far as mal-rotation of the tibial component. Effect of Internal Rotation of Tibial Component. By contrast, internal rotation of the tibial component by 22 degrees, which is only 4 degrees in excess of what has been described as tolerable by Berger and Rubash, displaces the tubercle 14 mm, a distance that would place the center of most patella over the center of the lateral femoral condyle, risking dislocation. Dynamically, as the knee flexes, if the tibia is able to rotate externally this forces the tubercle into an even more lateral position, guaranteeing that the patella will align lateral to the tip of the lateral femoral condyle, and dislocate. The design of femoral components, in particular the varus-valgus angle of the trochlear groove, has an effect on patellar tracking. This effect will be accentuated by the surgical alignment technique of the femoral and tibial components. Component positions that mimic the orientation of the normal anatomy usually include more valgus alignment of the femoral component. This rotates the proximal “entrance” of the femoral trochlear groove more medially, making it more difficult for the patella to descend in the trochlear groove

MPFL reconstruction has demonstrated a very high success rate with improved patella stability, physical function, and patient-reported outcomes. However technical error and a lack of consideration of anatomic risk factors have been shown to contribute to failure after MPFL reconstruction. Previous research has also reported a complication rate of 26% following surgery. The purposes of this study were to determine the re-dislocation rate, type and number of complications, and most common additional surgical procedures following MPFL reconstruction. Patients with symptomatic recurrent patellofemoral instability underwent an MPFL reconstruction (n = 268) and were assessed with a mean follow-up of 31.5 months (minimally 24-months). Concomitant procedures were performed in addition to the MPFL reconstruction in order to address significant anatomic or biomechanical characteristics. Failure of the patellofemoral stabilization procedure was defined as post-operative re-dislocation of the patella. Rates of complications and re-procedures were assessed for all patients. The re-dislocation rate following MPFL reconstruction was 5.6% (15/268). There were no patella fractures. A total of 49/268 patients (18.3%) returned to the operating room for additional procedures following surgery. The most common reason for additonal surgery was removal of symptomatic tibial tubercle osteotomy hardware in 24/268 patients (8.9%). A further 9.3% of patients underwent addtional surgery including revision MPFL reconstruction: with trochleoplasty 8/268 (3.0%), with tibial tubercule osteotomy 4/286 (1.5%) and with femoral derotation osteotomy 3/268 (1.1%); manipulation under anaesthesia for reduced knee range of motion 4/268 (1.5%); knee arthroscopy for pain 8/268 (3.0%); and cartilage restoration procedures 3/268 (1.1%). There was 1 case of wound debridement for surgical incision infection. MPFL reconstruction using an a la carte approach to surgical selection demonstrated a post-operative redislocation rate of 5.6%. The rate of complications following surgical stabilization was low, with the most common reason for additional surgery being removal of hardware