Undercorrection of stage II AAFF will result in a foot that remains unbalanced and predisposed to recurrence. Although symptoms will initially improve, long-term prognosis is guarded and recurrent deformity is possible. This is not uncommon when PTT repair is combined with an isolated medial calcaneal displacement osteotomy (MCO) and no other osseous procedures for late stage II AAFF. Although FDL tendon transfer with an isolated MCO has been described as an effective surgical approach to address less severe cases of stage II AAFF, it may not be adequate to correct more severe cases of stage II AAFF [1]. Myerson et al. found 97% of participants experienced pain relief and 94% showed improvement of function in 129 patients with stage II AAFF who underwent an FDL tendon transfer and a MCO. They recommend this combination of procedures if the patient has a flexible flatfoot, insignificant fixed forefoot supination, and less than 30% uncovering of the talonavicular joint on a weight-bearing AP X-ray [1]. FDL transfer and MCO in patients with deformities that go beyond these parameters may result in unacceptable outcomes. Additional procedures are needed for late stage II deformity [1, 2, 5]. In one study, patients who demonstrated undercorrection with a MCO, based on preoperative and postoperative hindfoot alignment radiographs, experienced less subjective improvement as opposed to a mild varus cohort [6]. The researchers concluded that patients who have residual postoperative valgus hindfoot moment arms continue to experience the everting pull of the Achilles tendon resulting in high loads along the medial longitudinal arch [6]. A radiographic study of 40 patients treated with either lateral column lengthening (LCL) or MCO demonstrated that LCL provided greater correction of the longitudinal arch and realignment of the medial column in comparison with the MCO [7].

Nonetheless, medial displacement osteotomy of the calcaneus is an effective procedure. A prospective study evaluated 30 patients with stage II AAFD undergoing flatfoot reconstruction. Preoperative and postoperative radiographs were reviewed to assess for correction in hindfoot alignment, which was measured by the change in hindfoot moment arm [8]. Correction in hindfoot alignment was primarily determined by the MCO, and concomitant procedures, including LCL, had a much lesser effect on hindfoot alignment during reconstruction [8]. More importantly, although the amount of LCL performed was positively correlated with the change in moment arm as an individual variable, the strength of the correlation was much lower than that of the MCO [8]. The authors concluded that the hindfoot alignment view can serve as a valuable preoperative measurement to help surgeons determine the proper amount of correction that is required (Fig. 21.3) [8]. Conti et al. assessed the relationship between postoperative hindfoot alignment following an MCO for stage II AAFD and patient outcomes. Evaluation was performed on 55 patients who underwent reconstruction for a stage II AAFF. Hindfoot alignment radiographs were taken before and after surgery. Average follow-up was 3.1 years. They concluded that hindfoot alignment between 0 and 5 mm of varus following stage II AAFF reconstruction was associated with the greatest improvement in clinical outcomes [6].

Undercorrection of medial displacement osteotomies can result from technical errors, especially when the osteotomy is performed too proximal. The intrinsic muscles, plantar fascia, etc. originate from the plantar aspect of the tuber segment. Displacement in this area can be hindered by these soft tissue attachments and result in insufficient translation and undercorrection. Medial displacement can often be facilitated by releasing the plantar structures. Osteotomy placement distal to the plantar intrinsic muscles allows easier medial translation of the tuber segment (Fig. 21.4).

Undercorrection can also result from inadequate lengthening of the lateral column at the time of surgery or loss of correction afterward due to bone graft resorption. Bone graft resorption can occur with premature weight-bearing, inadequate fixation, or inappropriate graft composition. According to Dayton et al., lateral column length must be maintained postoperatively to obtain an effective long-term correction. In their study, 22 patients underwent bone grafting for lateral column lengthening (LCL) using the traditional non-fixated technique. Conversely, 13 patients had the graft fixated with a locking plate to prevent compressive forces on the graft. Calcaneal length was measured 10 days and 12 weeks postoperatively to ascertain the mean amount of calcaneal shortening. Their results demonstrated that the mean amount of calcaneal shortening in the non-fixated group was 2.5 mm (range 0–6 mm). The mean amount of calcaneal shortening in the fixated group was 1.0 mm (range 0–3) [9]. These results might explain postoperative undercorrection following LCL without fixation. Locking plate fixation also reduced anterior displacement of calcaneal fragments [9]. In a recent study of 24 LCL patients, a wedge locking plate was found to be more effective in maintaining the mid-calcaneal length time when compared with a tricortical allograft wedge [10]. The mean decrease in mid-calcaneal length was greater for the tricortical allograft wedge group (2.8 ± 0.7 mm) than for the wedge locking plate group (0.6 ± 0.7 mm) at 6 months following surgery. Titanium trusses might also be effective in maintaining length following LCL (Fig. 21.5).

To avoid undercorrection/overcorrection with LCL procedures , one can implement digital planning for LCL as proposed by Siddiqui and Lamm. Preoperative digital planning accurately predicted the calcaneal graft size used during LCL when compared with the actual graft size utilized by the surgeon who was unaware of the predicted graft size. The preoperative graft measurement compared with the actual graft placed was within 0.4 mm (±1.8 mm) [11].

The authors prefer utilizing both MCO and LCL for most cases of stage II AAFF. [12] This provides the latitude to modify both osteotomies as needed and requires less displacement at both sites. This preserves a greater degree of hindfoot motion and results in less traction on neural structures. One can “dial in” the necessary correction at both sites with finer control. Overzealous displacement of the tuber segment can place excess tension on the lateral skin, resulting in wound dehiscence. We recommend osteoplasty of the overhanging portion of the calcaneus following displacement to help decompress the lateral skin (Fig. 21.6). Nonetheless, the risk of wound problems remains a potential problem with a large displacement.

Large amounts of distraction along the lateral column can result in lateral column overload, traction neuritis, and disruption of the planter soft tissues that stabilize the distal segment of the calcaneus with subsequent sagittal plane displacement and extended convalescence to allow adequate incorporation of the bone graft. The authors rarely use a graft size greater than 8.0 mm when combining LCL with a medial displacement osteotomy. Additionally, we no longer use structural grafts. Rather, we prefer lateral plates that maintain distraction and then “backfill” with bone graft (Fig. 21.7). The process of backfilling is carried out with a combination of frozen cancellous chips, bone marrow aspirate, and demineralized bone matrix putty. The plates allow for precise correction that can easily be changed during the procedure. Titanium trusses afford the same benefits.

Overcorrection of hindfoot alignment may shift plantar pressures laterally and has the potential to cause symptoms in the lateral foot. Hadfield et al. demonstrated that medial translation of the calcaneus resulted in increased peak pressures in the lateral forefoot as well as the lateral aspect of the heel [13]. The average pressure over the 1st and 2nd metatarsal regions of the forefoot decreased significantly after a MCO. However there was a significant increase in maximum forefoot pressure over the area of the 3rd–5th metatarsals [13]. Overcorrection of hindfoot alignment may shift plantar pressures laterally which can lead to discomfort along the lateral column [13]. The Achilles tendon is able to assist the PTT with inversion of the heel when the insertion point on the calcaneus is medial to the mid-tibial axis; however, overcorrection secondary to medial translation of the heel may result in symptoms due to lateral weight-bearing and/or excessive stiffness.

It is important to assess the magnitude of deformity and suppleness of soft tissues preoperatively as well as intraoperatively so that the appropriate amount of correction is obtained at the time of surgery. Furthermore, the amount of correction obtained with other procedures, such as lateral column lengthening, must also be taken into account. One should not translate the tuber segment the same amount for every case. Rather, the amount of displacement should be based on these factors.

Lateral column overload can result from overcorrection, failure to recognize/address forefoot varus, and failure to recognize/address medial column instability. LCL causes a significant shift of plantar load to lateral column, decreased contact in the medial midfoot through increased TN coverage, and higher maximum mean plantar pressures along the lateral midfoot [14]. A cadaveric study found significantly decreased talonavicular abduction and increased lateral column plantar pressures as they increased the amount of LCL performed from 6 to 10 mm. These findings suggest that overcorrection of the abduction deformity in patients with stage II AAFD may lead to less than ideal outcomes [15].

Ellis et al. performed a comparative cohort study with 20 patients, ten of which developed lateral column pain after undergoing a LCL procedure with additional adjunctive procedures [16]. The authors hypothesized that the patients with postoperative pain would have an increase in lateral column pressure measured by an EMED-ST plantar pressure platform. Results demonstrated a positive correlation with patients experiencing postoperative pain and an increased maximum force to the lateral aspect of the midfoot. Interestingly, the increased lateral plantar pressures did not correlate with excessive lengthening according to their radiographic measurements [17].

One of the technical challenges with LCL is determining the appropriate graft size or amount of lengthening. Unfortunately, there are no guidelines for estimating the necessary amount of LCL. Determination of graft size should be based on the degree of deformity and the suppleness of the soft tissues. In most cases, this is an intraoperative decision. Although intraoperative fluoroscopy (AP and lateral views) can help, simulated weight-bearing fluoroscopy is of limited value. It is difficult to simulate a patient’s body weight while trying to obtain appropriate radiographic views during surgery. Manual eversion testing is important following graft placement to ascertain range of motion. Our preference is to maintain at least 1/3–1/2 of eversion following LCL. Otherwise, patients may experience difficulty off-loading the lateral column during the mid-stance phase of gait. Some authors have reported the use of trial wedges as an effective way to determine appropriate graft size (Fig. 21.8). However, other reports suggest that trial wedges have limited accuracy and predictability [17].